private IQueryable _BuildOrderByQueryable(IQueryable baseQueryable, JsonQueryOrderBy jsonQueryOrderBy, bool isFirst)
{
var typeParameter = Expression.Parameter(baseQueryable.ElementType);
var orderByExpression = _GetOrderByExpression(typeParameter, jsonQueryOrderBy);
MethodInfo methodInfo;
if (isFirst)
{
if (jsonQueryOrderBy.Direction == JsonQueryOrderDirection.Asc)
{
methodInfo = new Func <IQueryable <object>, Expression <Func <object, object> >, IOrderedQueryable <object> >(Queryable.OrderBy)
.GetMethodInfo();
}
else
{
methodInfo = new Func <IQueryable <object>, Expression <Func <object, object> >, IOrderedQueryable <object> >(Queryable.OrderByDescending)
.GetMethodInfo();
}
}
else
{
if (jsonQueryOrderBy.Direction == JsonQueryOrderDirection.Asc)
{
methodInfo = new Func <IOrderedQueryable <object>, Expression <Func <object, object> >, IOrderedQueryable <object> >(Queryable.ThenBy)
.GetMethodInfo();
}
else
{
methodInfo = new Func <IOrderedQueryable <object>, Expression <Func <object, object> >, IOrderedQueryable <object> >(Queryable.ThenByDescending)
.GetMethodInfo();
}
}
var method = methodInfo
.GetGenericMethodDefinition()
.MakeGenericMethod(baseQueryable.ElementType, orderByExpression.ReturnType);
return(baseQueryable.Provider.CreateQuery(
Expression.Call(
instance: null,
method: method,
arg0: baseQueryable.Expression,
arg1: Expression.Quote(orderByExpression))));
}
private LambdaExpression _GetOrderByExpression(ParameterExpression typeParameter, JsonQueryOrderBy jsonQueryOrderBy)
{
var memberExpression = _GetMemberExpression(typeParameter, jsonQueryOrderBy.Selector);
var lambdaExpression = Expression.Lambda(
body: memberExpression,
typeParameter);
return(lambdaExpression);
}
