public static MethodCallExpression GenerateOrderMethodCall <T>(IQueryable <T> source, List <ExpressionSort> sorts) where T : class
{
if (sorts.Count == 0)
{
throw new InvalidOperationException();
}
Type type = typeof(T);
Type selectorResultType;
LambdaExpression selector = ExpressionRetriever.GetSortExpression <T>(sorts[0].PropertyName.ToString(), out selectorResultType);
MethodCallExpression resultExp = Expression.Call(typeof(Queryable),
"OrderBy" + (sorts[0].SortDirection == SortDirection.Descending ? sorts[0].SortDirection.ToString() : string.Empty),
new Type[] { type, selectorResultType },
source.Expression,
Expression.Quote(selector));
if (sorts.Count > 1)
{
for (int i = 1; i < sorts.Count; i++)
{
selector = ExpressionRetriever.GetSortExpression <T>(sorts[i].PropertyName.ToString(), out selectorResultType);
resultExp = Expression.Call(typeof(Queryable),
"ThenBy" + (sorts[i].SortDirection == SortDirection.Descending ? sorts[i].SortDirection.ToString() : string.Empty),
new Type[] { type, selectorResultType },
resultExp,
Expression.Quote(selector));
}
}
return(resultExp);
}
public static Expression <Func <T, bool> > ConstructFilterExpressionTree <T>(List <ExpressionFilter> filters)
{
if (filters.Count == 0)
{
return(null);
}
ParameterExpression param = Expression.Parameter(typeof(T), "t");
Expression exp = null;
if (filters.Count == 1)
{
exp = ExpressionRetriever.GetFilterExpression <T>(param, filters[0]);
}
else
{
exp = ExpressionRetriever.GetFilterExpression <T>(param, filters[0]);
for (int i = 1; i < filters.Count; i++)
{
if (filters[i].LogicalOperator == LogicalOperation.And)
{
exp = Expression.And(exp, ExpressionRetriever.GetFilterExpression <T>(param, filters[i]));
}
else if (filters[i].LogicalOperator == LogicalOperation.Or)
{
exp = Expression.Or(exp, ExpressionRetriever.GetFilterExpression <T>(param, filters[i]));
}
}
}
return(Expression.Lambda <Func <T, bool> >(exp, param));
}
