Linq orderby StringComparer dynamically

Question

From my previous question. C# Linq OrderBy(x => x.property)

I specified my linq orderby argument dynamically.

var param = “attribute1”;    
var propertyInfo = typeof(data).GetProperty(param);    
List<data> newList = _list
  .OrderBy(x => propertyInfo.GetValue(x, null))
  .ToList();

the problem is when I want to order this by StringComparison.OrdinalIgnoreCase:

List<data> newList = _list
  .OrderBy(x => propertyInfo.GetValue(x, null), StringComparer.OrdinalIgnoreCase)
  .ToList();

I receive this error:

The type arguments for method 'System.Linq.Enumerable.OrderBy(System.Collections.Generic.IEnumerable, System.Func, System.Collections.Generic.IComparer)' cannot be inferred from the usage. Try specifying the type arguments explicitly.

By not making it dynamic works. But I want this to order the dynamic argument.

List<data> newList = _list
  .OrderBy(x => x.Attribute, StringComparer.OrdinalIgnoreCase)
  .ToList();

Why you use this reflection approach if you only support string properties? — Tim Schmelter, May 04 '18 at 13:51
I also support this with integer and I use convert to convert string to integer. — Skyx, May 04 '18 at 13:55
Did you tried to pass your `data` type to your `OrderBy`? `OrderBy` method is also generic method, so probably you can pass `data` to it -> `OrderBy()`. — SᴇM, May 04 '18 at 13:55

score 4 · Accepted Answer · answered May 04 '18 at 13:48

4

Since propertyInfo.GetValue returns Object (not String) you have a syntax error. Try casting to String:

List<data> newList = _list
  .OrderBy(x => propertyInfo.GetValue(x, null) as String,
           StringComparer.OrdinalIgnoreCase)
  .ToList();

answered May 04 '18 at 13:48

Dmitry Bychenko

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Thanks! this is exactly what I am looking for. – Skyx May 04 '18 at 13:52

score 0 · Answer 2 · answered May 04 '18 at 13:52

0

Call ToString() on the result of GetValue():

List<data> newList = _list
  .OrderBy(x => propertyInfo.GetValue(x, null).ToString(), StringComparer.OrdinalIgnoreCase)
  .ToList();

answered May 04 '18 at 13:52

adjan

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Has the advantage that it "works " also for other types like `int`. But then you always have lexicographical order. `10` < `2`. Throws an exception if the property returns `null`. – Tim Schmelter May 04 '18 at 13:53

score 0 · Answer 3 · answered May 04 '18 at 14:06

As GetValue method has object as return type. so we need to typecast it to String and will resolve your issue.

  newList.OrderBy(x => (string)propertyInfo.GetValue(x, null), StringComparer.OrdinalIgnoreCase).ToList();

try it out. hope it will work.

Linq orderby StringComparer dynamically

3 Answers3