Retrieve Cache Data with Groups
Note
This feature is only available in NCache Enterprise Edition.
Once the items are added to the specific groups, the user can also
retrieve certain cache items or keys associated with that group.
Prerequisites
Retrieve Keys of a Particular Group
To return a list of keys that belongs to a specified group, you can
use the
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.
try
{
// Pre-conditions: Cache is connected
//A user wants to get the cache keys of all the customers from the West Coast
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.");
}
}
}
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
{
// Data with this group already exists in cache
String groupName = "Important Customers";
java.util.Collection<String> retrievedKeys = cache.getSearchService().getGroupKeys(groupName);
if (retrievedKeys != null && retrievedKeys.size() > 0)
{
// Iterate over the result
for (String key : retrievedKeys)
{
// Perform operations
}
}
else
{
// No data against the group found
}
}
catch (OperationFailedException ex)
{
// Exception can occur due to:
// Connection Failures
// Operation Timeout
// Operation performed during state transfer
}
catch (Exception ex)
{
// Any generic exception like NullPointerException or IllegalArgumentException
}
try {
// Data with this group already exists in cache
val groupName = "Important Customers"
val retrievedKeys = cache.getSearchService.getGroupKeys(groupName)
if (retrievedKeys != null && retrievedKeys.nonEmpty) {
// Iterate over the result
for (key <- retrievedKeys) {
// Perform operations
}
}
else {
// No data against the group found
}
}
catch {
case exception: Exception => {
// Handle any errors
}
}
// This is an async method
try
{
// Data with this group already exists in cache
var groupName = "Important Customers";
var searchService = await this.cache.getSearchService();
var retrievedKeys = await searchService.getGroupKeys(groupName);
if (retrievedKeys != null && retrievedKeys.size() > 0)
{
// Iterate over the result
retrievedKeys.forEach(key => {
// Perform Operations
});
}
else
{
// No data against the group found
}
}
catch(error)
{
// Handle errors
}
try:
# Data with this group already exists in cache
group_name = "Important 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:
# Perform Operations
print(key)
else:
# No data against the group found
print("No keys found")
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.
Retrieve Keys and Values of a Particular Group
To return the dictionary of the keys and the values that belong to a specified group, 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.
/* A user wants to get the cache keys along with the values of all the customers from the West Coast*/
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");
}
}
// Data with this group already exists in cache
String groupName = "Important Customers";
java.util.Map<String, Customer> result = cache.getSearchService().<Customer>getGroupData(groupName);
if (result != null && result.size() > 0)
{
// Iterate over the result
for (java.util.Map.Entry<String, Customer> item : result.entrySet())
{
// Perform operations
}
}
else
{
// No data against the group found
}
// Data with this group already exists in cache
val groupName = "Important Customers"
val result = cache.getSearchService.getGroupData(groupName)
if (result != null && result.nonEmpty) {
// Iterate over the result
for (item <- result) {
// Perform operations
}
}
else {
// No data against the group found
}
// This is an async method
// Data with this group already exists in cache
var groupName = "Important Customers";
var searchService = await this.cache.getSearchService();
var result = await searchService.getGroupData(groupName);
if (result != null && result.size() > 0)
{
// Iterate over the result
result.forEach(item => {
// Perform Operations
});
}
else
{
// No data against the group found
}
# Data with this group already exists in cache
group_name = "Important Customers"
search_service = cache.get_search_service()
result = search_service.get_group_data(group_name)
if result is not None and len(result) > 0:
# Iterate over the result
for key in result:
# Perform Operations
print(result[key])
else:
# No data against the group found
print("No data found")
Additional Resources
NCache provides a sample application for Groups on GitHub.
See Also
Add/Update Cache Data with Groups
Remove Cache Data with Group
Basic Operations for Caching Data
Tag Cache Data