public TResult Execute <TResult>(Expression expression)
{
var queryVisitor = new QueryVisitor(_queryVisitor.QueryInfo.Clone());
queryVisitor.Visit(expression);
var dataQueryResult = _dataQuery(queryVisitor.QueryInfo);
if (dataQueryResult is TResult)
{
return((TResult)dataQueryResult);
}
var methodCallExpression = (MethodCallExpression)expression;
if (methodCallExpression.Method.Name == "Count")
{
if (dataQueryResult is IEnumerable)
{
return((TResult)(object)((IEnumerable <object>)dataQueryResult).Count());
}
throw new NotImplementedException($"Cannot do {methodCallExpression.Method.Name}, return ${typeof(TResult)} or IEnumerable from query delegate");
}
if (methodCallExpression.Method.Name == "Single")
{
if (dataQueryResult is IEnumerable)
{
return((TResult)(object)((IEnumerable <object>)dataQueryResult).Single());
}
throw new NotImplementedException($"Cannot do {methodCallExpression.Method.Name}, return ${typeof(TResult)} or IEnumerable from query delegate");
}
var array = ((IEnumerable)dataQueryResult).Cast <IEnumerable <object> >().ToList();
var data = array.AsQueryable();
var newExp = Expression.Call(methodCallExpression.Method, Expression.Constant(data));
return(data.Provider.Execute <TResult>(newExp));
}
public IQueryable <TElement> CreateQuery <TElement>(Expression expression)
{
var queryVisitor = new QueryVisitor(_queryVisitor.QueryInfo.Clone());
queryVisitor.Visit(expression);
var methodCallExpression = (MethodCallExpression)expression;
if (methodCallExpression.Method.Name == "GroupBy")
{
var dataQueryResult = _dataQuery(queryVisitor.QueryInfo);
//if (dataQueryResult is IEnumerable<TElement>)
// return ((IEnumerable<TElement>) dataQueryResult).AsQueryable();
if (dataQueryResult is IEnumerable <Grouping> || dataQueryResult is IEnumerable <TElement> )
{
var asEls = ((IEnumerable <object>)dataQueryResult).Cast <TElement>();
return(asEls.AsQueryable());
//return (IQueryable<TElement>) ungroupedData.GroupBy((Expression<Func<object, TElement>>)queryVisitor.QueryInfo.GroupBy.KeySelector.Source);
//return (IQueryable<TElement>)(object)groupBy;
}
var ungroupedData = (dataQueryResult as IEnumerable <T>)?.AsQueryable();
if (ungroupedData != null)
{
if (queryVisitor.QueryInfo.GroupBy.KeyName != null)
{
return(ungroupedData.GroupBy(queryVisitor.QueryInfo.GroupBy.KeyName).Cast <TElement>());
}
}
}
if (methodCallExpression.Method.Name == "Select")
{
Func <QueryInfo, object> q = info => ((IEnumerable)_dataQuery(info)).Cast <T>().Select(queryVisitor.Transform <T, TElement>());
return(new DelegateQueryable <TElement>(q, null, queryVisitor));
}
return(new DelegateQueryable <TElement>(_dataQuery, expression, queryVisitor));
}
public QueryProvider(Func <QueryInfo, object> dataQuery, QueryVisitor queryVisitor = null)
{
_dataQuery = dataQuery;
this._queryVisitor = queryVisitor ?? new QueryVisitor();
}
