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 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 property of Groups.

CacheItem is added in the cache using the Insert method is 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.

Pre-Requisites

• .NET/.NET Core
• Java

• Include the following namespace in your application:
  • Alachisoft.NCache.Client
  • Alachisoft.NCache.Runtime
  • Alachisoft.NCache.Runtime.Exceptions
• The application must be connected to cache before performing the operation.
• Cache must be running.
• 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.

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

• .NET/.NET Core
• Java

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 = $"Customers:{customer.CustomerID}";

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

    // Specify the group
    cacheItem.Group = "Important Customers";

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

    // cacheItem is successfully added in the cache with group
}
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
}

Recommendation: 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

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

The following example updates group in a CacheItem.

• .NET/.NET Core
• Java

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

    // Retrieve the cacheItem from the cache
    string key = "ALFKI";
    var cacheItem = cache.GetCacheItem(key);

    // Set the group property of cache as null
    cacheItem.Group = null;

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

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

    // Specify the new group to be updated
    cacheItem.Group = "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
}
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
}

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 Groups at:

• GitHub

• Shipped with NCache: %NCHOME%\samples\dotnet\GroupsAndTags

See Also

Retrieve Cache Data with Groups
Remove Cache Data with Group
Basic Operations for Caching Data
Tag Cache Data