The following sections provide details on working with the IOperationResult interface.

CouchbaseClient's standard CRUD operations return Boolean values. When exceptions or failures occur, they are swallowed and false is returned.

While there might be scenarios where the cause of a failure is not important (e.g., non-persistent cache), it is likely that access to error information is necessary. To that end, the CouchbaseClient provides a set of complimentary ExecuteXXX methods, where XXX is the name of a standard CRUD operation.

var success = client.Get("foo"); //returns a Boolean

var result = client.ExecuteGet("foo"); //returns an IOperationResult

All ExecuteXXX methods return an instance of an implementation of the IOperationResult interface.

public interface IOperationResult
{
    bool Success { get; set; }

    string Message { get; set; }

    Exception Exception { get; set; }

    int? StatusCode { get; set; }

    IOperationResult InnerResult { get; set; }
}

For each of the ExecuteXXX methods, a typical use pattern would be to interrogate the possible error values on failure.

var result = client.ExecuteStore(StoreMode.Add, "foo", "bar");

if (! result.Success)
{
    Console.WriteLine("Store operation failed with message {0} and status code {1}", result.Message, result.StatusCode);
    
    if (result.Exception != null)
    {
        throw result.Exception;
    }
}

The Message property will contain details as to why an operation failed. The message might be from the server or it could be from the client. The StatusCode property is a Nullable<int> that will be populated from the server's response.

Like the standard CRUD methods, the Execute methods will swallow exceptions. However, caught exceptions are passed back to the caller by way of the Exception property. This allows the caller to check for an exception and throw it if exception behavior is desired.

There are several interfaces that extend IOperationResult to provide additional properties. Two important interfaces are the INullableOperationResult<T> and ICasOperationResult

public interface INullableOperationResult<T> : IOperationResult
{
    bool HasValue { get; }
    T Value { get; set; }
}

public interface ICasOperationResult : IOperationResult
{
    ulong Cas { get; set; }
}

The INullableOperationResult<T> interface is extended by the IGetOperationResult, providing Get operations with properties to get the retrieved value.

var result = client.ExecuteGet("foo");

if (! result.Success)
{
    Console.WriteLine("Get operation failed with message {0} and status code {1}", result.Message, result.StatusCode);
    
    if (result.Exception != null)
    {
        throw result.Exception;
    }
}    

if (result.HasValue)
{
    var value = result.Value;
}
else if (result.StatusCode == 1)
{   
    Console.WriteLine("Key does not exist");
}

IGetOperationResult also extends ICasOperationResult. Therefore, it is possible to get the CAS value from an ExecuteGet operation. The snippet below demonstrates the generic ExecuteGet method.

var result = client.ExecuteGet<City>("CT_Hartford");

if (result.Success)
{
    var city = result.Value;
    city.Population = 124775;
    client.ExecuteStore(StoreMode.Set, "CT_Hartford", city, result.Cas); //will fail if Cas is not the same value on server
}

ExecuteStore methods return IStoreOperationResult instances.

var result = client.ExecuteStore(StoreMode.Add, "foo", "bar");

if (! result.Success)
{
    Console.WriteLine("Get operation failed with message {0} and status code {1}", result.Message, result.StatusCode);
    
    if (result.StatusCode == 2)
    {   
        Console.WriteLine("Key already exists");
    }
    
    if (result.Exception != null)
    {
        throw result.Exception;
    }
}

IStoreOperationResult also extends ICasOperationResult. Therefore, it is possible to get the CAS value from an ExecuteStore operation.

var city = new City() { Name = "Hartford", State = "CT" };
var result = client.ExecuteStore(StoreMode.Add, "CT_Hartford", city);

if (result.Success)
{
    city.Population = 124775;
    client.ExecuteStore(StoreMode.Set, "CT_Hartford", city, result.Cas); //will fail if Cas is not the same value on server
}

The IMutateOperationResult, IConcatOperationResult interfaces also return the CAS value. These interfaces are returned by ExecuteIncrement/ExecuteDecrement and ExecuteAppend/ExecutePrepend respectively. IRemoveOperationResult includes only the properties found in IOperationResult.

For more information on which API methods support ExecuteXXX variants, see the API reference.