Add/Update Cache Data with Groups

NCache allows the user to add an item in the data 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 to the cache using the Insert method, a recommended approach with the 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 Add/Update Groups in Data Cache

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

// Preconditions: 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);
}

// Precondition: Cache is already connected

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

// If customer is not found in the cache, fetch from the database and add to cache
if (customer == null) {
    Customer customer = fetchCustomerFromDB("Customer:ALFKI");

    // Create a new CacheItem to store the customer with metadata
    CacheItem cacheItem = new CacheItem(customer);

    // Specify the group for the cache item
    cacheItem.setGroup("East Coast Customers");
    System.out.println("Group Set Successfully");

    // Add customer object to cache with group and metadata
    cache.insert(customerKey, cacheItem);
    System.out.println("Item Added Successfully");
}

# Precondition: 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

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

// 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

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 that can be used to add data to the data cache. The CacheItem also lets you set the group as a property of the CacheItem.

The following example updates the 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);

// 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
CacheItem cacheItem = null;

cacheItem = cache.getCacheItem(customerKey);

// Specify the new group to be updated
cacheItem.setGroup("West Coast Customers");
System.out.println("Group Set Successfully");

// Reinsert the cacheItem in the cache with updated groups
cache.insert(customerKey, cacheItem);
System.out.println("Item Updated Successfully");

# Precondition: 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

// This is an async method

// 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

Additional Resources

NCache provides a sample application for Groups on GitHub.

Add/Update Cache Data with Groups

Prerequisites Add/Update Groups in Data Cache

Note

Update Group of a CacheItem

Additional Resources

See Also

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