LINQ Wildcard Operators Usage

Note

This feature is only available in NCache Enterprise Edition.

NCache supports multiple wildcard operators with LINQ.

Pre-Requisites

For flawless program delivery, ensure the following:

Include the following namespaces in your application:
- AlalchiSoft.NCache.Client
- Alachisoft.NCache.Linq (located at %NCHOME%\integrations\LINQToNCache)
- Alachisoft.NCache.Runtime.Exceptions
Indexing for searchable objects and their attributes need to be configured first as explained in Configuring Query Indexes in Administrator's Guide.
The application must be connected to cache before performing the operation.
Cache must be running.
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

The following code uses the NCacheQuery class with two of the Wildcard operators 'StartsWith' and 'EndsWith' for determining products in a given range of values. It is assumed the cache contains Product objects.

Wildcard 'StartsWith':

A Product class LINQ object is created which returns products with names that start with "Bev".

Using Simple LINQ Query Expression:

try
{
    // Precondition: Cache is already connected 
    // Create custom class LINQ object 
    IQueryable<Product> products = new NCacheQuery<Product>(cache);

    // LINQ query to search cache
    var result = from product in products
    where product.ProductName.StartsWith("Bev")
    select product;

    if (result != null)
    {
      foreach (Product product in result)
        {
           // Perform operations
        }            
    }
    else
    {
        // No result in the cache related to query
    }
}
catch (OperationFailedException ex)
{
    //NCache specific exception
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any generic exception like ArgumentNullException or ArgumentException
}

Using Lambda Expression:

try
{
    // Precondition: Cache is already connected

    // Create custom class LINQ object 
    IQueryable<Product> products = new NCacheQuery<Product>(cache);

    // Lambda expression for same query
    var result = products.Select(p => p).Where(p => p.ProductName.StartsWith("Be"));

   if (result != null)
    {
     foreach (Product product in result)
        {
           // Perform operations
        }  
    }
    else
    {
        // No result in the cache related to query
    }
}
catch (OperationFailedException ex)
{
    //NCache specific exception
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any generic exception like ArgumentNullException or ArgumentException
}

Wildcard Operator 'EndsWith':

A Product class LINQ object is created which returns products with names that end with "ages".