/// <summary>
/// Obtain the DataServiceContext from the incoming enumerable
/// </summary>
/// <param name="items">An IEnumerable that may be a DataServiceQuery or QueryOperationResponse object</param>
/// <returns>DataServiceContext instance associated with the input</returns>
private static DataServiceContext GetContextFromItems(IEnumerable <T> items)
{
Debug.Assert(items != null, "items != null");
DataServiceQuery <T> dataServiceQuery = items as DataServiceQuery <T>;
if (dataServiceQuery != null)
{
DataServiceQueryProvider queryProvider = dataServiceQuery.Provider as DataServiceQueryProvider;
Debug.Assert(queryProvider != null, "Got DataServiceQuery with unknown query provider.");
DataServiceContext context = queryProvider.Context;
Debug.Assert(context != null, "Query provider must always have valid context.");
return(context);
}
QueryOperationResponse queryOperationResponse = items as QueryOperationResponse;
if (queryOperationResponse != null)
{
Debug.Assert(queryOperationResponse.Results != null, "Got QueryOperationResponse without valid results.");
DataServiceContext context = queryOperationResponse.Results.Context;
Debug.Assert(context != null, "Materializer must always have valid context.");
return(context);
}
throw new ArgumentException(Strings.DataServiceCollection_CannotDetermineContextFromItems);
}
/// <summary>
/// query object
/// </summary>
/// <param name="expression">expression for query</param>
/// <param name="provider">query provider for query</param>
public DataServiceQuery(Expression expression, DataServiceQueryProvider provider)
{
Debug.Assert(null != provider.Context, "null context");
Debug.Assert(expression != null, "null expression");
Debug.Assert(provider is DataServiceQueryProvider, "Currently only support Web Query Provider");
this.queryExpression = expression;
this.queryProvider = provider;
}
/// <summary>
/// query object of a function which returns a collection of items
/// </summary>
/// <param name="expression">expression for query</param>
/// <param name="provider">query provider for query</param>
/// <param name="isComposable">whether this query is composable</param>
public DataServiceQuery(Expression expression, DataServiceQueryProvider provider, bool isComposable)
{
Debug.Assert(provider.Context != null, "null context");
Debug.Assert(expression != null, "null expression");
Debug.Assert(provider is DataServiceQueryProvider, "Currently only support Web Query Provider");
this.queryExpression = expression;
this.queryProvider = provider;
this.IsComposable = isComposable;
this.IsFunction = true;
}
/// <summary>
/// constructor
/// </summary>
/// <param name="expression">expression for query</param>
/// <param name="provider">query provider for query</param>
/// <param name="isComposable">whether this query is composable</param>
internal DataServiceOrderedQuery(Expression expression, DataServiceQueryProvider provider, bool isComposable)
: base(expression, provider, isComposable)
{
}
/// <summary>
/// constructor
/// </summary>
/// <param name="expression">expression for query</param>
/// <param name="provider">query provider for query</param>
internal DataServiceOrderedQuery(Expression expression, DataServiceQueryProvider provider)
: base(expression, provider)
{
}
/// <summary>
/// query object
/// </summary>
/// <param name="expression">expression for query</param>
/// <param name="provider">query provider for query</param>
public DataServiceQuery(Expression expression, DataServiceQueryProvider provider)
: this(expression, provider, true)
{
this.IsFunction = false;
}
