Add/Update Cache Data with Groups

Note

This feature is only available in NCache Enterprise Edition.

NCache allows the user to add an item in the cache with a certain group. There can only be a single item associated with a single group. CacheItem is a custom class provided by NCache which can be used to add data to the cache. CacheItem also lets you set additional specifications associated with an object as a property of groups.

CacheItem is added in the cache using the Insert method, a recommended approach with group if no item already exists in the cache with the specified key.

Whereas the Add operation fails if the key already exists and an exception will be thrown.

Prerequisites

To learn about the standard prerequisites required to work with all NCache client side features please refer to the given page on Client Side API Prerequisites.
Custom classes/searchable attributes must be indexed as explained in Configuring Query Indexes.
For API details refer to: ICache, CacheItem, Add, Insert, Group, GetCacheItem.

In the following example, data group is set by assigning it as a property of CacheItem containing the object customer.

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

    /*In an online-store, customers from different regions need to be grouped accordingly
    A customer has signed in to the website from the East Coast region*/

    // Create a unique cache key for this customer.
    string customerKey = $"Customer:ALFKI";

    // Get customer from cache
    Customer customer = cache.Get<Customer>(customerKey);

    // Get customer from database if not found in cache
    if (customer == null)
    {
        customer = FetchCustomerFromDB("ALFKI");

        // Create a new CacheItem
        var cacheItem = new CacheItem(customer);

        // Specify the group
        cacheItem.Group = "East Coast Customers";

        // Add customer object to cache with group
        cache.Add(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 ArgumentNullException or ArgumentException
}

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

    // Get customer from database against given customer ID
    Customer customer = fetchCustomerFromDB("ALFKI");

    // Create a unique cache key for this customer
    String key = "Customer:" + customer.getCustomerID();

    // Create a new CacheItem
    CacheItem cacheItem = new CacheItem(customer);

    // Specify the group
    cacheItem.setGroup("ImportantCustomers");

    // Add customer object to cache with group
    CacheItemVersion version = cache.insert(key, cacheItem);

    // cacheItem is successfully added in the cache with group
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

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


    // Get customer from database against given customer ID
    val customer = fetchCustomerFromDB("ALFKI")

    // Create a unique cache key for this customer
    val key = "Customer:" + customer.getCustomerId

    // Create a new CacheItem
    val cacheItem = new CacheItem(customer)

    // Specify the group
    cacheItem.setGroup("ImportantCustomers")

    // Add customer object to cache with group
    val version = cache.insert(key, cacheItem)

    // cacheItem is successfully added in the cache with group
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

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

    // Get customer from database against given customer ID
    var customer = this.fetchCustomerFromDB("ALFKI");

    // Create a unique cache key for this customer.
    var key = "Customers:" + customer.getCustomerID();

    // Create a new CacheItem
    var cacheItem = new ncache.CacheItem(customer);

    // Specify the group
    cacheItem.setGroup("Important Customers");

    // Add customer object to cache with group
    var version = await this.cache.insert(key, cacheItem);

    // cacheItem is successfully added in the cache with group
}
catch(error)
{
    // Handle errors
}

try:
    # Pre-condition: Cache is already connected

    # Get customer from database
    customer = fetch_customer_from_db()

    # Create a unique cache key for this customer.
    key = "Customers:" + customer.get_customer_id()

    # Create a new CacheItem
    cache_item = ncache.CacheItem(customer)

    # Specify the group
    cache_item.set_group("Important Customers")

    # Add customer object to cache with group
    version = cache.insert(key, cache_item)

    # CacheItem is successfully added in the cache with group
except Exception as exp:
    # 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.

Update Group of a CacheItem

The data group of a CacheItem can also be updated. A CacheItem is a custom class provided by NCache which can be used to add data to the cache. The CacheItem also lets you set the group as a property of the CacheItem.

The following example updates group in a CacheItem.


    // A customer has signed in to the website from a different region i.e.  West Coast

    string customerKey = $"Customer:ALFKI";

    // Retrieve the cacheItem from the cache
    var cacheItem = cache.GetCacheItem(customerKey);

    // Specify the new group to be updated
    cacheItem.Group = "West Coast Customers";

    // Reinsert the cacheItem in the cache with updated groups
    cache.Insert(customerKey, cacheItem);


    // Pre-condtion: CacheItem is added with the group

    // Get customer from database against given customer ID
    Customer customer = fetchCustomerFromDB(1000);

    // Create a unique cache key for this customer.
    String key = "Customer:" + customer.getCustomerID();

    //Retrieve cache item from cache
    CacheItem cacheItem = cache.getCacheItem(key);

    // Specify the new group to be updated
    cacheItem.setGroup("US Customers");

    // Re-insert the cacheItem in the cache with updated groups
    cache.insert(key, cacheItem);

    // CacheItem is successfully added in the cache with updated group


    // Pre-condition: CacheItem is added with the group

    // Get customer from database against given customer ID
    val customer = fetchCustomerFromDB(1000)

    // Create a unique cache key for this customer.
    val key = "Customer:" + customer.getCustomerId

    //Retrieve cache item from cache
    val cacheItem = cache.getCacheItem(key)

    // Specify the new group to be updated
    cacheItem.setGroup("US Customers")

    // Re-insert the cacheItem in the cache with updated groups
    cache.insert(key, cacheItem)

    // CacheItem is successfully added in the cache with updated group

    // This is an async method

    // Pre-condtion: CacheItem is added with the group

    // Retrieve the cacheItem from the cache
    var key = "ALFKI";
    var cacheItem = this.cache.getCacheItem(key);

    // Re-insert the item in the cache after the removal of group
    await this.cache.insert(key, cacheItem);

    // Get cacheitem with the updated version
    cacheItem = this.cache.getCacheItem(key);

    // Specify the new group to be updated
    cacheItem.setGroup("US Customers");

    // Re-insert the cacheItem in the cache with updated groups
    await this.cache.insert(key, cacheItem);

    // CacheItem is successfully added in the cache with updated group


    # Pre-condition: CacheItem is added with the group

    # Retrieve the CacheItem with old group from the cache
    key = "ALFKI"
    cache_item = cache.get_cacheitem(key)

    # Specify the new group to be updated
    cache_item.set_group("US Customers")

    # Re-insert the cacheItem in the cache with updated groups
    cache.insert(key, cache_item)

    # CacheItem is successfully added in the cache with updated group

Additional Resources

NCache provides a sample application for Groups on GitHub.

Add/Update Cache Data with Groups

Note

Prerequisites

Note

Update Group of a CacheItem

Additional Resources

See Also