Retrieve Cache Data with Groups [Deprecated]

Once the items are added to the specific groups in cache, the user can also retrieve certain cache items or keys associated with that group.

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.
For API details, refer to: ICache, GetGroupKeys, GetGroupData, SearchService.

Create a new Console Application.
Install either of the following NuGet packages in your .NET client application:
- Enterprise: Install-Package Alachisoft.NCache.SDK -Version 4.9.1.0
Create a new Console Application.
Make sure that the data being added is serializable.
Add NCache References by locating %NCHOME%\NCache\bin\assembly\4.0 and adding Alachisoft.NCache.Web and Alachisoft.NCache.Runtime as appropriate.
Include the Alachisoft.NCache.Web.Caching namespace in your application.
To learn more about the NCache Legacy API, please download the NCache 4.9 documents available as a .zip file on the Alachisoft Website.

Retrieve Keys of a Particular Group

To return a list of keys that belong to a specified group in cache, you can use GetGroupKeys method that returns a list of keys mapped under the group passed to this API.

Important

Passing empty strings for the group will return an empty result set.
Passing only the value of the group will return all the keys mapped under the group.
Passing null to this API for the group will throw an ArgumentNullException.

// Precondition: Cache is connected
// Data with this group already exists in cache
string groupName = "West Coast Customers";

ICollection<string> keys = cache.SearchService.GetGroupKeys(groupName);

if (keys != null && keys.Count > 0)
{
    // Iterate over the result
    foreach (var key in keys)
    {
        Console.WriteLine($"Key '{key}' belongs to '{groupName}' group.");
    }
}

// Precondition: Cache is connected
// Data with this group already exists in cache
String groupName = "West Coast Customers";

Collection<String> keys = cache.getSearchService().getGroupKeys(groupName);

if (keys != null && !keys.isEmpty())
{
    // Iterate over the result
    for (String key : keys)
    {
        System.out.println("Key '" + key + "' belongs to '" + groupName + "' group.");
    }
}

# Precondition: Cache is connected
# Data with this group already exists in cache
group_name = "West Coast Customers"

search_service = cache.get_search_service()
retrieved_keys = search_service.get_group_keys(group_name)

if retrieved_keys is not None and len(retrieved_keys) > 0:

    # Iterate over the result
    for key in retrieved_keys:
        print(f"Key '{key}' belongs to '{group_name}' group.")

// Precondition: Cache is connected
// This is an async method
// Data with this group already exists in cache
const groupName = "West Coast Customers";

const searchService = await cache.getSearchService();
const retrievedKeys = await searchService.getGroupKeys(groupName);
if (retrievedKeys != null && retrievedKeys.length > 0)
{
    // Iterate over the result
    for (const key of retrievedKeys)
    {
        console.log(`Key '${key}' belongs to '${groupName}' group.`);
    }
}

// Using NCache Enterprise 4.9.1
// Precondition: Cache is connected
// Data with this group already exists in cache
string groupName = "West Coast Customers";
string subGroupName = "Retail"; // Example subgroup

// Fetch keys from cache using legacy API for both group and subgroup
ArrayList keys = cache.GetGroupKeys(groupName, subGroupName);

if (keys != null && keys.Count > 0)
{
    foreach (object key in keys)
    {
        Console.WriteLine("Key '" + key + "' belongs to group '" + groupName + "' and subgroup '" + subGroupName + "'.");
    }
}

Note

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

Retrieve Keys and Values of a Particular Group

To return the dictionary of the keys and the values that belong to a specified group in cache, the GetGroupData method can be used. This method returns a dictionary of keys and values mapped under the group passed to this API.

The following example retrieves the keys and the values that belong to the group West Coast Customers.

// Precondition: Cache is connected
// Data with this group already exists in cache
string groupName = "West Coast Customers";

IDictionary<string, Customer> retrievedDictionary = cache.SearchService.GetGroupData<Customer>(groupName);

if (retrievedDictionary != null)
{
    foreach (KeyValuePair<string, Customer> retrievedItem in retrievedDictionary)
    {
        Console.WriteLine($"Customer '{retrievedItem.Value.ContactName}' having Key '{retrievedItem.Key}' belongs to West Coast");
    }
}

// Precondition: Cache is connected
// Data with this group already exists in cache
String groupName = "West Coast Customers";

Map<String, Object> retrievedDictionary = cache.getSearchService().getGroupData(groupName);

if (retrievedDictionary != null && !retrievedDictionary.isEmpty())
{
    for (Map.Entry<String, Object> retrievedItem : retrievedDictionary.entrySet())
    {
        Object value = retrievedItem.getValue();

        if (value instanceof Customer)
        {
            Customer customer = (Customer) value;
            System.out.println("Customer '" + customer.getContactName() + "' having Key '" + retrievedItem.getKey() + "' belongs to West Coast");
        }
    }
}

# Precondition: Cache is connected
# Data with this group already exists in cache
group_name = "West Coast Customers"

search_service = cache.get_search_service()
retrieved_dict = search_service.get_group_data(group_name)

if retrieved_dict is not None and len(retrieved_dict) > 0:

    for key, customer_map in retrieved_dict.items():

        customer = Customer(
            customer_id=customer_map.get("customer_id"),
            contact_name=customer_map.get("name"),
            region=customer_map.get("region")
        )

        print(f"Customer '{customer.contact_name}' having Key '{key}' belongs to West Coast")

// This is an async method
// Precondition: Cache is connected
// Data with this group already exists in cache
const groupName = "West Coast Customers";

const searchService = await cache.getSearchService();
const retrievedDictionary = await searchService.getGroupData(groupName);

if (retrievedDictionary != null)
{
    retrievedDictionary.forEach((customer, key) =>
    {
        console.log(`Customer '${customer.ContactName}' having Key '${key}' belongs to ${groupName}`);
    });
}

// Using NCache Enterprise 4.9.1
// Precondition: Cache is connected
string groupName = "West Coast Customers";
string subGroupName = "Retail";

ArrayList keys = cache.GetGroupKeys(groupName, subGroupName);

if (keys != null && keys.Count > 0)
{
    foreach (string key in keys)
    {
        Customer customer = cache.Get(key) as Customer;
        if (customer != null)
        {
            Console.WriteLine($"Customer '{customer.ContactName}' having Key '{key}' belongs to '{groupName}'");
        }
    }
}

Additional Resources

NCache provides a sample application for Groups on GitHub.