Retrieve Cache Data with Tags

Note

This feature is only available in NCache Enterprise Edition.

Once the data is tagged with one or multiple tags, the data can be retrieved using these tags. Data can be retrieved by a specified tag or one or all tags.

Prerequisites

Install the following NuGet package in your application:
- Enterprise: Alachisoft.NCache.SDK
Include the following namespaces in your application:
- Alachisoft.NCache.Client
- Alachisoft.NCache.Runtime.Caching
- Alachisoft.NCache.Runtime.Exceptions
Cache must be running.
The application must be connected to cache before performing the operation.
Make sure that the data being added is serializable.
For API details refer to: ICache, Tag, GetKeysByTag, GetKeysByTags, GetByTag
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Add the following Maven dependencies in your pom.xml file:

<dependency>
    <groupId>com.alachisoft.ncache</groupId>
    <artifactId>ncache-client</artifactId>
    <version>x.x.x</version>
</dependency>

Import the following packages in your application:
- import com.alachisoft.ncache.runtime.exceptions.*;
- import com.alachisoft.ncache.runtime.caching.*;
- import com.alachisoft.ncache.client.*;
Cache must be running.
The application must be connected to cache before performing the operation.
Make sure that the data being added is serializable.
For API details refer to: Cache, Tag, getKeysByTag, getKeysByTags, getByTag, getByTags
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Install and include the following module in your application:
- Enterprise: const ncache = require('ncache-client')
Cache must be running.
The application must be connected to cache before performing the operation.
For API details refer to: Cache, Tag, getKeysByTag, getKeysByTags, getByTag, getByTags
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Install the NCache Python client by executing the following command:

# Enterprise Client
pip install ncache-client

Import the NCache module in your application.
Cache must be running.
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Add the following Maven dependencies in your pom.xml file:

<dependency>
    <groupId>com.alachisoft.ncache</groupId>
    <artifactId>ncache-scala-client</artifactId>
    <version>x.x.x</version>
</dependency>

Import the following packages in your application:
- import com.alachisoft.ncache.scala.client.*;
Cache must be running.
The application must be connected to cache before performing the operation.
Make sure that the data being added is serializable.
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Retrieve Keys Associated with a Tag

Keys can be retrieved from the cache by tags either by GetKeysByTag, GetKeysByAnyTag or GetKeysByAllTags. All these methods are explained below.

GetKeysByTag

GetKeysByTag is a method which retrieves the keys by one specified tag. The specified tag is the search criteria for the data in the cache. For Java, the method used for retrieving keys by tag is getKeysByTag.

Following example retrieves the keys of the items associated with the specified tag from the cache.

Warning

Providing Null tag array will throw an ArgumentNullException or NullPointerException.

try
{
    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys with the Tag 'Important Customers' are retrieved
    // Retrieved Cache keys are then stored in an ICollection
    ICollection<string> retrievedKeys = cache.SearchService.GetKeysByTag(tags[0]);

    if (retrievedKeys != null && retrievedKeys.Count > 0)
    {
        // Iterate over key result
        foreach (var key in retrievedKeys)
        {
            // Perform operations            
        }
    }
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any other generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys with the Tag 'Important Customers' are retrieved
    // Retrieved Cache keys are then stored in an ICollection
    Collection retrievedKeys = cache.getKeysByTag(tags[0]);

    // Iterate over key result
    if (retrievedKeys != null)
    {
        for (Object keys : retrievedKeys) 
        { 
            // Perform operations        
        }
    }
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

// This is an async method
try
{
    // Following tags are created and item is added in the cache with these tags
    var tags = new ncache.Tag[2];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");

    // Keys with the Tag 'Important Customers' are retrieved
    // Retrieved Cache keys are then stored in an ICollection
    var searchService = await this.cache.getSearchService();
    var retrievedKeys = await searchService.getKeysByTags(tags[0]);

    if (retrievedKeys != null && retrievedKeys.size() > 0)
    {
        // Iterate over key result
        retrievedKeys.forEach(key => {
            // Perform operations
        });
    }
}
catch(error)
{
    // Handle errors
}

try:
    # Following tags are created and item is added in the cache with these tags
    tags = [
        ncache.Tag("Important Customers"),
        ncache.Tag("East Coast Customers")
    ]

    # Keys with the Tag 'Important Customers' are retrieved
    # Retrieved Cache keys are then stored in a list
    search_service = cache.get_search_service()
    retrieved_keys = search_service.get_keys_by_tag(tags[0])

    if retrieved_keys is not None and len(retrieved_keys) > 0:
        # Iterate over key result
        for key in retrieved_keys:
            # Perform operations
            print(key)
except Exception as exp:
    # Handle errors

try {
    // Following tags are created and item is added in the cache with these tags

    var tags: List[Tag] = List()
    tags = Tag("Important Customers") :: tags
    tags = Tag("East Coast Customers") :: tags

    // Keys with the Tag 'Important Customers' are retrieved
    // Retrieved Cache keys are then stored in a Collection

    val retrievedKeys = cache.getSearchService.getKeysByTag(tags.head)

    // Iterate over key result
    if (retrievedKeys != null) {
      for (keys <- retrievedKeys) {
        // Perform operations
      }
    }
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

GetKeysByTag with Wildcard expressions

NCache also provides support for retrieving keys from the cache using tags with wildcard expressions using the method getKeysByTag(Wildcard). The special characters supported in wild search by NCache are:

*: Used as a substitute for zero or more characters in the string.
?: Used as a substitute for a single character in the string.

The following example retrieves the keys of the items associated with tags along with wild card expressions.

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and items are added in the cache with these tags
    Tag[] tags = new Tag[3];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");
    tags[2] = new Tag("West Coast Customers");

    // Retrieves all the keys associated with customers
    // containing any prefix before customer
    // i.e 'Important Customers' as well as 'East Coast Customers' and 'West Coast Customers'
    ICollection<string> retrieveKeys = cache.SearchService.GetKeysByTag("*Customers");

    if (retrieveKeys != null && retrieveKeys.Count > 0)
    {
        // Iterate over key result
        foreach (var key in retrieveKeys)
        {
            // Perform operations                      
        }
    }

    // Retrieves all the keys associated with the tags
    // 'East Coast Customers' and 'West Coast Customers'
    ICollection<string> retrieveCoastCustomersKeys = search.GetKeysByTag("??st Customers");

    if (retrieveCoastCustomersKeys != null && retrieveCoastCustomersKeys.Count > 0)
    {
        // Perform operations as done for 'Customers'
    }
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any other generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and items are added in the cache with these tags
    Tag[] tags = new Tag[3];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");
    tags[2] = new Tag("West Coast Customers");

    // Retrieves all the keys associated with customers
    // containing any prefix before customer
    // i.e 'Important Customers' as well as 'East Coast Customers' and 'West Coast Customers'
    Collection<string> retrieveKeys = cache.getSearchService().getKeysByTag("*Customers");

    if (retrieveKeys != null )
    {
        // Iterate over key result
        foreach (var key : retrieveKeys)
        {
            // Perform operations                      
        }
    }

    // Retrieves all the keys associated with the tags
    // 'East Coast Customers' and 'West Coast Customers'
    ICollection<string> retrieveCoastCustomersKeys = cache.getKeysByTag("??st Customers");

    if (retrieveCoastCustomersKeys != null)
    {
        // Perform operations as done for 'Customers'
    }
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
   // Any generic exception like NullPointerException or IllegalArgumentException
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and items are added in the cache with these tags
    var tags = new ncache.Tag[3];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");
    tags[2] = new ncache.Tag("West Coast Customers");

    // Retrieves all the keys associated with customers
    // containing any prefix before customer
    // i.e 'Important Customers' as well as 'East Coast Customers' and 'West Coast Customers'
    var searchService = await this.cache.getSearchService();
    var retrieveKeys = await searchService.getKeysByTag("*Customers");

    if (retrieveKeys != null && retrieveKeys.Count > 0)
    {
        // Iterate over key result
        retrieveKeys.forEach(key => {
            // Perform operations
        });
    }

    // Retrieves all the keys associated with the tags
    // 'East Coast Customers' and 'West Coast Customers'
    var searchService = await this.cache.getSearchService();
    var retrieveCoastCustomersKeys = await searchService.getByTags("??st Customers");

    if (retrieveCoastCustomersKeys != null && retrieveCoastCustomersKeys.size() > 0)
    {
        // Perform operations as done for 'Customers'
    }
}
catch(error)
{
   // Handle errors
}

try:
    # Following tags are created and item is added in the cache with these tags
    tags = [
        ncache.Tag("Important Customers"),
        ncache.Tag("East Coast Customers"),
        ncache.Tag("West Coast Customers")
    ]

    # Keys with the Tag 'Important Customers' are retrieved
    # Retrieved Cache keys are then stored in a list
    search_service = cache.get_search_service()
    retrieved_keys = search_service.get_keys_by_tag(None, "*Customers")

    if retrieved_keys is not None and len(retrieved_keys) > 0:
        # Iterate over key result
        for key in retrieved_keys:
            # Perform operations
            print(key)

    # Retrieve all the keys associated with the tags 'East Coast Customers' and 'West Coast Customers'
    retrieved_coast_customers_keys = search_service.get_by_tag(None, "??st Customers")

    if retrieved_coast_customers_keys is not None and len(retrieved_coast_customers_keys) > 0:
        # Iterate over key result
        for key in retrieved_coast_customers_keys:
            # Perform operations
            print(key)

except Exception as exp:
    # Handle errors

try {
    // Pre-condition: Cache is already connected

    // Following tags are created and items are added in the cache with these tags
    var tags: List[Tag] = List()
    tags = Tag("Important Customers") :: tags
    tags = Tag("East Coast Customers") :: tags
    tags = Tag("West Coast Customers") :: tags

    // Retrieves all the keys associated with customers
    // containing any prefix before customer
    // i.e 'Important Customers' as well as 'East Coast Customers' and 'West Coast Customers'
    var retrievedKeys = cache.getSearchService.getKeysByTag("*Customers");

    if (retrievedKeys != null )
    {
      // Iterate over key result
      for (key <- retrievedKeys)
      {
        // Perform operations
      }
    }

    // Retrieves all the keys associated with the tags
    // 'East Coast Customers' and 'West Coast Customers'
    var retrieveCoastCustomersKeys = cache.getSearchService.getKeysByTag("??st Customers");

    if (retrieveCoastCustomersKeys != null)
    {
      // Perform operations as done for 'Customers'
    }
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

GetKeysByAnyTag

GetKeysByTag is a method with the search option as ByAnyTag where multiple tags are provided and the key(s) matching ANY of the provided tags will be retrieved. In case of Java, getKeysByAnyTag is used to retrieve keys matching any of the tags provided.

Following example retrieves the keys which matches ANY of the tag provided in the list tags.

Warning

Providing Null tag list will throw an ArgumentNullException or NullPointerException.

try
{
    // Following tags are created and item is added in the cache with these tags

    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys associated with any of the Tag in the list 'tags' are retrieved
    // Retrieved Cache keys are then stored in an ICollection
    ICollection<string> keys = cache.SearchService.GetKeysByTags(tags, TagSearchOptions.ByAnyTag);

    // Check if any keys are failed to retrieve
    if (keys != null && keys.Count > 0)
    {
        // Iterate over key result
        foreach (var key in keys)
        {
            // Perform operations
        }
    }
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any other generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Following tags are created and items are added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys associated with any of the Tag in the list 'tags' are retrieved
    // Retrieved Cache keys are then stored in a Collection
    Collection retrievedKeys = cache.getKeysByAnyTag(productTags[0]);

    // Iterate over key result
    if (retrievedKeys != null)
    {
        for (Object key : retrievedKeys) 
        {
            // Perform operations        
        }
    }
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and items are added in the cache with these tags
    var tags = new ncache.Tag[2];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");

    // Keys associated with any of the Tag in the list 'tags' are retrieved
    // Retrieved Cache keys are then stored in an ICollection
    var searchService = await this.cache.getSearchService();
    var keys = await searchService.getByTags(tags,ncache.TagSearchOptions.ByAnyTag);

    // Check if any keys are failed to retrieve
    if (keys != null && keys.size() > 0)
    {
        // Iterate over key result
        keys.forEach(key => {
            // Perform operations
        });
    }
}
catch(error)
{
   // Handle errors
}

try:
    # Pre-condition: Cache is already connected

    # Following tags are created and items are added in the cache with these tags
    tags = [
        ncache.Tag("Important Customers"),
        ncache.Tag("East Coast Customers")
    ]

    # Keys associated with any of the Tag in the list 'tags' are retrieved
    # Retrieved Cache keys are then stored in an ICollection
    search_service = cache.get_search_service()
    keys = search_service.get_by_tags(tags, ncache.TagSearchOptions.BY_ANY_TAG)

    # Check if any keys failed to be retrieved
    if keys is not None and len(keys) > 0:
        # Iterate over key result
        for key in keys:
            # Perform operations
            print(key)
except Exception as exp:
    # Handle errors

try {
    // Following tags are created and items are added in the cache with these tags

    var tags: List[Tag] = List()
    tags = Tag("Important Customers") :: tags
    tags = Tag("East Coast Customers") :: tags

    // Keys associated with any of the Tag in the list 'tags' are retrieved
    // Retrieved Cache keys are then stored in a Collection
    val retrievedKeys = cache.getSearchService.getByTags(tags, TagSearchOptions.ByAnyTag)

    // Iterate over key result
    if (retrievedKeys != null) {
      for (key <- retrievedKeys) {
        // Perform operations
      }
    }
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

GetKeysByAllTags

GetKeysByTag is a method with the search option as ByAllTags where multiple tags are provided and key(s) matching ALL of the provided tags will be retrieved. For Java, getKeysByAllTags is used to search for items matching all the tags provided.

The following example retrieves the keys of items in the cache containing ALL the tags in the list tags.

Warning

Providing Null tag list will throw an ArgumentNullException or NullPointerException.

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys associated with all of the Tags in the list 'tags' are retrieved
    // Retrieved Cache keys are then stored in an ICollection
    ICollection<string> keys = cache.SearchService.GetKeysByTags(tags, TagSearchOptions.ByAllTags);

    // Check if any keys are failed to retrieve
    if (keys != null && keys.Count > 0)
    {
        // Iterate over key result
        foreach (var key in keys)
        {
            // Perform operations 
        }
    }
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}   
catch (Exception ex)
{
    // Any other generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Following tags are created and items are added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys associated with all of the Tags in the list 'tags' are retrieved
    // Retrieved Cache keys are then stored in an ICollection
    Collection retrievedKeys = cache.getKeysByAllTags(tags[0]);

    // Iterate over key result
    if (retrievedKeys != null)
    {
        for (Object key : retrievedKeys) 
        {
            // Perform operations        
        }
    }
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and items are added in the cache with these tags
    var tags = new ncache.Tag[2];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");

    // Keys associated with any of the Tag in the list 'tags' are retrieved
    // Retrieved Cache keys are then stored in an ICollection
    var searchService = await this.cache.getSearchService();
    var keys = await searchService.getByTags(tags,ncache.TagSearchOptions.ByAllTags);

    // Check if any keys are failed to retrieve
    if (keys != null && keys.size() > 0)
    {
        // Iterate over key result
        keys.forEach(key => {
            // Perform operations
        });
    }
}
catch(error)
{
    // Handle errors
}

try:
    # Pre-condition: Cache is already connected

    # Following tags are created and items are added in the cache with these tags
    tags = [
        ncache.Tag("Important Customers"),
        ncache.Tag("East Coast Customers")
    ]

    # Keys associated with any of the Tag in the list 'tags' are retrieved
    # Retrieved Cache keys are then stored in an ICollection
    search_service = cache.get_search_service()
    keys = search_service.get_by_tags(tags, ncache.TagSearchOptions.BY_ALL_TAGS)

    # Check if any keys failed to be retrieved
    if keys is not None and len(keys) > 0:
        # Iterate over key result
        for key in keys:
            # Perform operations
            print(key)
except Exception as exp:
    # Handle errors

try {
    // Following tags are created and items are added in the cache with these tags

    var tags: List[Tag] = List()
    tags = Tag("Important Customers") :: tags
    tags = Tag("East Coast Customers") :: tags

    // Keys associated with all of the Tag in the list 'tags' are retrieved
    // Retrieved Cache keys are then stored in a Collection
    val retrievedKeys = cache.getSearchService.getByTags(tags, TagSearchOptions.ByAllTags)

    // Iterate over key result
    if (retrievedKeys != null) {
      for (key <- retrievedKeys) {
        // Perform operations
      }
    }
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

Retrieve Cached Data from Cache Containing Tag

Similar to keys, cached items (keys and values) can also be retrieved from the cache either by GetByTag, GetByAnyTag or GetByAllTags. All these methods are explained below.

GetByTag

GetByTag is a method in which a single tag is provided and all the ""keys and values"" associated with that tag are retrieved. In java section of the code, the method used for this purpose is getByTag.

Following example retrieves the keys and values against these keys, associated with the tag Important Customers.

Warning

Providing Null tag array will throw an ArgumentNullException or NullPointerException.

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys and values with the Tag 'Important Customers' and 'East Coast Customers' are retrieved 
    IDictionary<string, Customer> retrievedDictionary = cache.SearchService.GetByTags<Customer>(tags, TagSearchOptions.ByAllTags);

    if (retrievedDictionary != null)
    {
        foreach (KeyValuePair<string, Customer> keyValuePair in retrievedDictionary)
        {
            //perform operations
        }
    }
    else
    {
        // Object not of Customer type
    }
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any other generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys and values with the Tag 'Important Customers' and 'East Coast Customers' are retrieved 
    HashMap result = cache.getByTag(tags[0]);

    // Iterate over result
    if (result != null)
    {
        for (KeyValuePair<string, Customer> keyValuePair : result)
        {
            // Perform operations
        }
    }
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    var tags = new ncache.Tag[2];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");

    // Keys and values with the Tag 'Important Customers' and 'East Coast Customers' are retrieved 
    var searchService = await this.cache.getSearchService();
    var retrievedList = await searchService.getByTags(tags,ncache.TagSearchOptions.ByAllTags);

    if (retrievedList != null)
    {
        retrievedList.forEach(keyValuePair => {
            // Perform operations
        });
    }
    else
    {
        // Object not of Customer type
    }
}
catch(error)
{
    // Handle errors
}

try:
    # Following tags are created and item is added in the cache with these tags
    tags = [
        ncache.Tag("Important Customers"),
        ncache.Tag("East Coast Customers")
    ]

    # Keys with the Tag 'Important Customers' are retrieved
    # Retrieved Cache keys are then stored in a list
    search_service = cache.get_search_service()
    retrieved_items = search_service.get_by_tag(tags[0])

    if retrieved_items is not None and len(retrieved_items) > 0:
        # Iterate over the result
        for item in retrieved_items:
            # Perform operations
            print(retrieved_items[item])
except Exception as exp:
    # Handle errors

try {
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    var tags: List[Tag] = List()
    tags = Tag("Important Customers") :: tags
    tags = Tag("East Coast Customers") :: tags

    // Keys and values with the Tag 'Important Customers' and 'East Coast Customers' are retrieved
    val result = cache.getSearchService.getByTag(tags.head)

    // Iterate over result
    if (result != null) {
      for (keyValuePair <- result) {
        // Perform operations
      }
    }
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

GetByTag with Wildcard expressions

NCache also provides support for retrieving keys from the cache using tags with wildcard expressions using the method getByTag(Wildcard). The special characters supported in wild search by NCache are:

*: Used as a substitute for zero or more characters in the string.
?: Used as a substitute for a single character in the string.

The following example retrieves the data of the items associated with tags along with wild card expressions.

try
{
   // Pre-condition: Cache is already connected

    // Following tags are created and items are added in the cache with these tags
    Tag[] tags = new Tag[3];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");
    tags[2] = new Tag("West Coast Customers");

    // Retrieves all the data associated with customers
    // containing any prefix before customer
    // i.e 'Important Customers' as well as 'East Coast Customers' and 'West Coast Customers'
    IDictionary<string, Customer> retrievedDictionary = cache.SearchService.GetByTag<Customer>("*Customers");

    if (retrievedDictionary != null)
    {
        foreach (KeyValuePair<string, Customer> keyValuePair in retrievedDictionary)
        {
            //perform operations
        }
    }
    else
    {
        // Object not of Customer type
    }

    // Retrieves all the data associated with the tags
    // 'East Coast Customers' and 'West Coast Customers'
    IDictionary<string, Customer> retrievedDictionaryEW = search.GetByTag<Customer>("??st Customers");
    if (retrievedDictionary != null)
    {
        foreach (KeyValuePair<string, Customer> keyValuePair in retrievedDictionary)
        {
            //perform similar operations as done for "customers"
        }
    }
    else
    {
        // Object not of Customer type
    }
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any other generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and items are added in the cache with these tags
    Tag[] tags = new Tag[3];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");
    tags[2] = new Tag("West Coast Customers");

    // Retrieves all the data associated with customers
    // containing any prefix before customer
    // i.e 'Important Customers' as well as 'East Coast Customers' and 'West Coast Customers'
    java.util.Map<String, Customer> retrievedDictionary = cache.getSearchService().<Customer>getByTag("*Customers");
    Collection<String> keys = cache.getSearchService().<Customer>getKeysByTag("*Customers");

    if (keys != null)
    {
        if(keys.size()>0)
        {
            retrievedDictionary = cache.removeBulk(keys,null);
        }
        for (java.util.Map.Entry<String, Customer>  customer: retrievedDictionary.entrySet())
        {
            //perform operations
        }
    }
    else
    {
        // Object not of Customer type
    }

    // Retrieves all the data associated with the tags
    // 'East Coast Customers' and 'West Coast Customers'
    java.util.Map<String, Customer> retrievedDictionaryEW = cache.getSearchService().<Customer>getByTag("??st Customers");

    if (retrievedDictionary != null)
    {
        for (java.util.Map.Entry<String, Customer> customer : retrievedDictionaryEW.entrySet())
        {
            //perform similar operations as done for "customers"
        }
    }
    else
    {
        // Object not of Customer type
    }
}
catch (Exception ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and items are added in the cache with these tags
    var tags = new ncache.Tag[3];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");
    tags[2] = new ncache.Tag("West Coast Customers");

    // Retrieves all the data associated with customers
    // containing any prefix before customer
    // i.e 'Important Customers' as well as 'East Coast Customers' and 'West Coast Customers'

    var searchService = await this.cache.getSearchService();
    var retrievedList = await searchService.getByTag("*Customers");  

    if (retrievedList != null)
    {
        retrievedList.forEach(keyValuePair => {
            // Perform operations
        });
    }
    else
    {
        // Object not of Customer type
    }

    // Retrieves all the data associated with the tags
    // 'East Coast Customers' and 'West Coast Customers'

    var searchService = await this.cache.getSearchService();
    var retrievedListEW = await searchService.getByTag("??st Customers");

    if(retrievedList != null)
    {
        retrievedList.forEach(keyValuePair => {
            // Perform similar operations as done for "customers"
        });
    }
    else
    {
        // Object not of Customer type
    }
}
catch(error)
{
   // Handle errors
}

try:
    # Following tags are created and item is added in the cache with these tags
    tags = [
        ncache.Tag("Important Customers"),
        ncache.Tag("East Coast Customers"),
        ncache.Tag("West Coast Customers")
    ]

    # Retrieves all the data associated with customers containing any prefix before customer i.e.
    # 'Important Customers' as well as 'East Coast Customers' and 'West Coast Customers'

    search_service = cache.get_search_service()
    retrieved_items = search_service.get_by_tag(None, "*Customers")

    if retrieved_items is not None:
        for item in retrieved_items:
            # Perform operations
            print(item)
    else:
        # Object not of Customer type
        print("Object not found")

    # Retrieve all the data associated with the tags 'East Coast Customers' and 'West Coast Customers'

    retrieved_items_ew = search_service.get_by_tag(None, "??st Customers")

    if retrieved_items_ew is not None:
        for item in retrieved_items_ew:
            # Perform operations
            print(item)
    else:
        # Object not of Customer type
        print("No object found")
except Exception as exp:
    # Handle errors

try {
    // Pre-condition: Cache is already connected

    // Following tags are created and items are added in the cache with these tags
    var tags: List[Tag] = List()
    tags = Tag("Important Customers") :: tags
    tags = Tag("East Coast Customers") :: tags
    tags = Tag("West Coast Customers") :: tags

    // Retrieves all the data associated with customers
    // containing any prefix before customer
    // i.e 'Important Customers' as well as 'East Coast Customers' and 'West Coast Customers'
    var retrievedDictionary = cache.getSearchService.getByTag("*Customers")

    if (retrievedDictionary != null) {
      for (customer <- retrievedDictionary) {
        //perform operations
      }
    }
    else {
      // Items not found
    }

    // Retrieves all the data associated with the tags
    // 'East Coast Customers' and 'West Coast Customers'
    val retrievedDictionaryEW = cache.getSearchService.getByTag("??st Customers")

    if (retrievedDictionary != null) {
      for (customer <- retrievedDictionaryEW) {
        //perform similar operations
      }
    }
    else {
    }
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

GetByAnyTag

GetByTag is a method and ByAnyTag is the search option in which a list of tags is provided and all the ""keys and values"" associated with ANY of the tags in the tag list are retrieved. For Java, getByAnyTag is used for retrieving keys and their values matching any of the tags provided.

Following example retrieves the keys and values against these keys, associated with any of the tags in the list tags.

Warning

Providing Null tag list will throw an ArgumentNullException or NullPointerException.

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in  the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys and values with any of the Tags in the tags list are retrieved
    IDictionary<string, Customer> retrievedDictionary = cache.SearchService.GetByTags<Customer>(tags, TagSearchOptions.ByAnyTag);

    if (retrievedDictionary != null)
    {
        foreach (KeyValuePair<string, Customer> keyValuePair in retrievedDictionary)
        {
            //perform operations
        }
    }
    else
    {
        // Object not of Customer type
    }
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any other generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys and values with any of the Tags in the tags list are retrieved
    HashMap result = cache.getByAnyTag(tags);

    // Iterate over result
    if (result != null)
    {
        // Perform operations
    }
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    var tags = new ncache.Tag[2];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");

    // Keys and values with any of the Tags in the tags list are retrieved

    var searchService = await this.cache.getSearchService();
    var retrievedList = await searchService.getByTags(tags,ncache.TagSearchOptions.ByAnyTag);

    if (retrievedList != null)
    {
        retrievedList.forEach(keyValuePair => {
            // Perform operations
        });
    }
    else
    {
        // Object not of Customer type
    }
}
catch(error)
{
    // Handle errors
}

try:
    # Pre-condition: Cache is already connected

    # Following tags are created and item is added in the cache with these tags
    tags = [
        ncache.Tag("Important Customers"),
        ncache.Tag("East Coast Customers")
    ]

    # Keys and values with any of the Tags in the tags list are retrieved
    search_service = cache.get_search_service()
    retrieved_items = search_service.get_by_tags(tags, ncache.TagSearchOptions.BY_ANY_TAG)

    if retrieved_items is not None:
        for item in retrieved_items:
            # Perform operations
            print(item)
    else:
        # Object not of Customer type
        print("Object not found")

except Exception as exp:
    # Handle errors

try {
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    var tags: List[Tag] = List()
    tags = Tag("Important Customers") :: tags
    tags = Tag("East Coast Customers") :: tags

    // Keys and values with any of the Tags in the tags list are retrieved
    val result = cache.getSearchService.getByTags(tags, TagSearchOptions.ByAnyTag)

    // Iterate over result
    if (result != null) {
      // Perform operations
    }
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

GetByAllTags

GetByTag is a method and ByAllTags is the search option in which a list of tags is provided and all the ""keys and values"" associated with ALL of the tags in the tag list are retrieved. getByAllTags is used to get they keys and values matching all the tags in case of Java.

Following example retrieves the keys and values against these keys, associated with all of the tags in the list tags.

Warning

Providing Null tag list will throw an ArgumentNullException or NullPointerException.

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys and values with all of the Tags in the tags list are retrieved
    IDictionary<string, Customer> retrievedDictionary = cache.SearchService.GetByTags<Customer>(tags, TagSearchOptions.ByAllTags);

    if (retrievedDictionary != null)
    {
        foreach (KeyValuePair<string, Customer> keyValuePair in retrievedDictionary)
        {
            // Perform operations
        }
    }
    else
    {
        // Object not of Customer type
    }
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any other generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys and values with all of the Tags in the tags list are retrieved
    HashMap result = cache.getByAllTags(tags);

    // Iterate over result
    if (result != null)
    {
        // Perform operations
    }
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    var tags = new ncache.Tag[2];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");

    // Keys and values with any of the Tags in the tags list are retrieved

    var searchService = await this.cache.getSearchService();
    var retrievedList = await searchService.getByTags(tags,ncache.TagSearchOptions.ByAllTags);

    if (retrievedList != null)
    {
        retrievedList.forEach(keyValuePair => {
            // Perform operations
        });
    }
    else
    {
        // Object not of Customer type
    }
}
catch(error)
{
    // Handle errors
}

try:
    # Pre-condition: Cache is already connected

    # Following tags are created and item is added in the cache with these tags
    tags = [
        ncache.Tag("Important Customers"),
        ncache.Tag("East Coast Customers")
    ]

    # Keys and values with any of the Tags in the tags list are retrieved
    search_service = cache.get_search_service()
    retrieved_items = search_service.get_by_tags(tags, ncache.TagSearchOptions.BY_ALL_TAGS)

    if retrieved_items is not None:
        for item in retrieved_items:
            # Perform operations
            print(item)
    else:
        # Object not of Customer type
        print("Object not found")

except Exception as exp:
    # Handle errors

try {
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    var tags: List[Tag] = List()
    tags = Tag("Important Customers") :: tags
    tags = Tag("East Coast Customers") :: tags

    // Keys and values with any of the Tags in the tags list are retrieved
    val result = cache.getSearchService.getByTags(tags, TagSearchOptions.ByAllTags)

    // Iterate over result
    if (result != null) {
      // Perform operations
    }
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

Additional Resources

NCache provides sample application for Tags on GitHub.

Retrieve Cache Data with Tags

Note

Prerequisites

Retrieve Keys Associated with a Tag

GetKeysByTag

Warning

GetKeysByTag with Wildcard expressions

GetKeysByAnyTag

Warning

GetKeysByAllTags

Warning

Retrieve Cached Data from Cache Containing Tag

GetByTag

Warning

GetByTag with Wildcard expressions

GetByAnyTag

Warning

GetByAllTags

Warning

Additional Resources

See Also