protected override Expression VisitMethodCall(MethodCallExpression node)
{
if (node.Method.IsGenericMethod)
{
var genericMethodDefinition = node.Method.GetGenericMethodDefinition();
// find cachable query extention calls
if (genericMethodDefinition == EntityFrameworkQueryableExtensions.CacheableMethodInfo)
{
// get parameter with "last one win"
_options = node.Arguments
.OfType <ConstantExpression>()
.Where(a => a.Value is CacheableOptions)
.Select(a => (CacheableOptions)a.Value)
.Last();
_isCacheable = true;
// cut out extension expression
return(Visit(node.Arguments[0]));
}
}
return(base.VisitMethodCall(node));
}
/// <summary>
/// Visit the query expression tree and find extract cachable parameter
/// </summary>
/// <param name="expression">Query expression</param>
/// <param name="isCacheable">Is expression marked as cacheable</param>
/// <param name="timeToLive">Timespan befor expiration of cached query result</param>
/// <returns></returns>
public virtual Expression GetExtractCachableParameter(Expression expression, out Boolean isCacheable, out CacheableOptions options)
{
var visitedExpression = Visit(expression);
isCacheable = _isCacheable;
options = _options;
return(visitedExpression);
}
