C# enum display on Expression.ToString()

Question

When I call the ToString() methods on an expression, the enum value are printed as integers. Is there some format overload ?

Maybe I can create an derviedclass from expression and override some ToString Method. Any thoughts ?

Here is a sample :

    public enum LengthUnits { METRES, FEET };

    Expression<Func<LengthUnits, bool>> isFeet = l => l == LengthUnits.FEET;
    string isFeetFunctinoAsString = isFeet.ToString();

The value of isFeetFunctinoAsString is :

    u => (Convert(u) = 1)

I do not want the 1 but FEET .

Can you post a small, complete example that demonstrates the problem? — Andrew Hare, Sep 10 '09 at 15:10

score 1 · Answer 1 · edited Oct 15 '09 at 20:48

1

This is not possible in an expression, as even before you can interfere with the expression, the enum has already been converted to an integer.

You might want to check when there is a binaryexpression with the parameter on the left or right side, and convert by hand, but I won't recommend that.

edited Oct 15 '09 at 20:48

Ether

53,118
13
86
159

answered Sep 10 '09 at 15:29

Jan Jongboom

26,598
9
83
120

1

Because you should create a whole new ToString method, because an expression tree doesn't have the same structure every time. You can have things like: l=>l==LengthUnits.FEET ; l=>LengthUntits.Feet==l ; l=>l>2 && l != LengthUnits.FEET etc. etc. – Jan Jongboom Sep 10 '09 at 17:04

score 0 · Answer 2 · edited May 23 '17 at 12:13

0

Enum.GetName(Type MyEnumType,  object enumvariable)

From this question: C# String enums

Hope this is what you are looking for.

edited May 23 '17 at 12:13

Community

1
1

answered Sep 10 '09 at 15:11

James Lawruk

30,112
19
130
137

Binoj Antony · Answer 3 · 2009-09-10T15:23:20.863

0

myEnumValue.ToString ( "G" );

Taken from here

[Edit]

string isFeetFunctinoAsString = isFeet.ToString("G");

edited Sep 10 '09 at 15:23

answered Sep 10 '09 at 15:12

Binoj Antony

15,886
25
88
96

I think the question should answer whether this is available within the convertion from an expression tree to a string, not just the general .NET version. – Jan Jongboom Sep 10 '09 at 15:30
1

this does not work , there is no overload for the expression.ToString() method – Toto Sep 10 '09 at 15:46
LInk from this answer appears to be broken. Microsoft documentation regarding format strings for enumerations can be found here: https://msdn.microsoft.com/en-us/library/c3s1ez6e(v=vs.110).aspx (retrieved at time of writing). Method ToString(string format) is available for Enumeration but not for Expression. – Manfred Feb 18 '17 at 02:51

score 0 · Answer 4 · answered Sep 10 '09 at 15:37

Here is what you would need to do to extract the integer value and parse it as the enumeration type:

BinaryExpression binaryExpression = (BinaryExpression)isFeet.Body;

LengthUnits units 
    = (LengthUnits)Enum.Parse
        (typeof(LengthUnits), 
        binaryExpression.Right.ToString());

But that won't give you exactly what you want. C# enumerations are like constants in the way that their values are literally transplanted into the source whenever they are referenced. The expression you have is demonstrating this as the literal value of the enumeration is embedded in the expression's string representation.

C# enum display on Expression.ToString()

4 Answers4