private QueryCollectionValue RewriteGroupingElements(QueryCollectionValue groupings, LinqLambdaExpression elementSelectorLambda)
{
var groupingElementType = (QueryGroupingType)groupings.Type.ElementType;
var rewrittenGroupingType = new QueryGroupingType(groupingElementType.Key.PropertyType, elementSelectorLambda.Body.ExpressionType, groupingElementType.EvaluationStrategy);
var rewrittenGroupings = new List <QueryValue>();
foreach (var grouping in groupings.Elements.Cast <QueryStructuralValue>())
{
QueryCollectionValue elements = grouping.GetCollectionValue("Elements");
var rewrittenElements = elements.Select(e => this.EvaluateLambda <QueryValue>(elementSelectorLambda, e));
var rewrittenGrouping = rewrittenGroupingType.CreateNewInstance();
rewrittenGrouping.SetValue("Key", grouping.GetValue("Key"));
rewrittenGrouping.SetValue("Elements", rewrittenElements);
rewrittenGroupings.Add(rewrittenGrouping);
}
var result = rewrittenGroupingType.CreateCollectionType().CreateCollectionWithValues(rewrittenGroupings);
return(result);
}
/// <summary>
/// Resolves types for the specified expression.
/// </summary>
/// <param name="expression">The expression to resolve types for.</param>
/// <returns>Expression with resolved types.</returns>
public QueryExpression Visit(LinqGroupByExpression expression)
{
var source = this.ResolveTypes(expression.Source);
var sourceType = ValidateSourceIsACollection(source);
var keySelector = this.ResolveLambdaTypes(expression.KeySelector, sourceType);
var elementSelector = expression.ElementSelector != null?this.ResolveLambdaTypes(expression.ElementSelector, sourceType) : null;
var keyCollectionType = keySelector.Body.ExpressionType.CreateCollectionType();
var elementCollectionType = expression.ElementSelector != null?elementSelector.Body.ExpressionType.CreateCollectionType() : sourceType;
if (expression.ResultSelector != null)
{
// resolve lambda strips the collection out of parameters, but the second parameter to the result is a collection
// so we pass collection of collections
var resultSelector = this.ResolveLambdaTypes(expression.ResultSelector, keyCollectionType, elementCollectionType.CreateCollectionType());
var resultType = resultSelector.Body.ExpressionType;
return(new LinqGroupByExpression(source, keySelector, elementSelector, resultSelector, resultType.CreateCollectionType()));
}
else
{
var groupingType = new QueryGroupingType(keySelector.Body.ExpressionType, elementCollectionType.ElementType, this.EvaluationStrategy);
return(new LinqGroupByExpression(source, keySelector, elementSelector, null, groupingType.CreateCollectionType()));
}
}
