How can I remove a particular Named Tag from a cache item in NCache?

To remove a particular Named Tag, retrieve the CacheItem from the cache, invoke the remove() method on the NamedTags dictionary using the tag's key, and then re-insert the item into the cache.

What happens if I set NamedTags to null in a CacheItem?

Setting the NamedTags property of a CacheItem to null results in the removal of all associated searchable metadata tags for that item when it is re-inserted into the cache.

Remove Data with Named Tags

The items added with Named Tags to the cache can also be removed from the cache using the same Named Tags. Additionally, like updating Named Tags, they can also be removed via CacheItem. This is a custom class provided by NCache which can be used to add data to the cache. To remove Named Tag via CacheItem, the Named Tag property of the CacheItem is set as null.

Prerequisites

Before using the NCache Client-side APIs, ensure that the following prerequisites are fulfilled:

Install the following NuGet packages in your .NET client application:
- Enterprise: Alachisoft.NCache.SDK
- Open Source: Alachisoft.NCache.Opensource.SDK
Include the following namespaces in your application:
The cache must be running.
Make sure that the data being added is serializable.
For API details, refer to: ICache, CacheItem, NamedTags, GetCacheItem, Insert, Remove.

Add the following Maven dependencies for your Java client application in pom.xml file:

<dependency>
    <groupId>com.alachisoft.ncache</groupId>
    <!--for NCache Enterprise-->
    <artifactId>ncache-client</artifactId>
    <version>x.x.x</version>
</dependency>

Import the following packages in your Java client application:
- import com.alachisoft.ncache.client.*;
- import com.alachisoft.ncache.runtime.exceptions.*;
- import com.alachisoft.ncache.runtime.caching.*;
The cache must be running.
Make sure that the data being added is serializable.
For API details, refer to: Cache, CacheItem, NamedTagsDictionary, getCacheItem, insert.

The following example removes the Named Tags via CacheItem:

try
{
  // Precondition: Cache is already connected

  // A user wants to end the VIP membership discount offer
  // So this Named Tag needs to be removed.

  string customerKey = "Customer:ALFKI";

  // Retrieve the CacheItem using the key
  CacheItem cacheItem = cache.GetCacheItem(customerKey);

  // Remove tag from dictionary
  cacheItem.NamedTags.Remove("VIP_Membership_Discount");

  // Reinsert the cacheItem in the cache with Named Tags removed
  cache.Insert(customerKey, cacheItem);
}
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
{
  // Precondition: Cache is already connected

  // A user wants to end the VIP membership discount offer
  // So this Named Tag needs to be removed.

  String customerKey = "Customer:ALFKI";

  // Retrieve the CacheItem using the key
  CacheItem cacheItem = cache.getCacheItem(customerKey);

  // Remove tag from dictionary
  cacheItem.getNamedTags().remove("VIP_Membership_Discount");

  // Reinsert the cacheItem in the cache with Named Tags removed
  cache.insert(customerKey, cacheItem);
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer            
}
catch (Exception ex)
{
    // Any generic exception like IllegalArgumentException or NullPointerException 
}

try:
    # Precondition: Cache is already connected

    # A user wants to end the VIP membership discount offer
    # So this Named Tag needs to be removed.

    customer_key = "Customer:ALFKI"

    # Retrieve the CacheItem using the key
    cache_item = cache.get_cacheitem(customer_key)

    # Set the Named Tags property of the cacheItem as null
    cache_item.set_named_tags(None)

    # Re-insert the cacheItem in the cache with Named Tags removed
    cache.insert(customer_key, cache_item)

except Exception as error:
    # Exception can occur due to:
    # Connection Failures
    # Operation Timeout
    # Operation during state transfer
    print("An error occurred:", str(error))

try
{
  // This is an async method
  // Precondition: Cache is already connected

  // A user wants to end the VIP membership discount offer
  // So this Named Tag needs to be removed.

  var customerKey = "Customer:ALFKI";

  // Retrieve the CacheItem using the key
  var cacheItem = await this.cache.getCacheItem(customerKey);

  // Set the Named Tags property of the cacheItem as null
  cacheItem.setNamedTags(null);

  // Reinsert the cacheItem in the cache with Named Tags removed
  await this.cache.insert(customerKey, cacheItem);
}
catch (error)
{
    // Handle errors
}

Note

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

Note

The cacheItem.NamedTags.Remove(tagName) method will remove the Named Tag associated with the tagName. If all Named Tags are removed from the Named Tags dictionary, it becomes empty. When the cache item is inserted into the cache with this empty dictionary, it will not retain any Named Tags.

Additional Resources

NCache provides a sample application for NamedTags on GitHub.

Remove Data with Named Tags

Prerequisites

Note

Note

Additional Resources

See also

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