Json.NET StringEnumConverter not always working

Question

I have an enum:

public enum FilterOperator
    {
        [EnumMember(Value = "eq")]
        Equals,
        [EnumMember(Value = "gt")]
        GreaterThan,
        [EnumMember(Value = "lt")]
        LessThan,
        [EnumMember(Value = "in")]
        In,
        [EnumMember(Value = "like")]
        Like
    }

and a class that includes an enum property:

public class GridFilter
{
    [JsonProperty("operator")]
    [JsonConverter(typeof(StringEnumConverter))]
    public FilterOperator Operator { get; set; }
}

The object is passed in via a WebAPI action and deserializes as expected for "like" and "in" but it doesn't for "lg" or "gt". Any idea why?

UPDATE: Well the reason "like" and "in" work is that they match the enum name. Renaming GreaterThan to Gt (etc) works. So the real issue is why isn't StringEnumConverter being used?

Answer 1

Well, you must place the [JsonConverter(typeof(StringEnumConverter))] attribute directly on the enum declaration instead of the Operator property of GridFilter if you want it to be used when deserializing outside the context of the class GridFilter:

[JsonConverter(typeof(StringEnumConverter))] // Add this
public enum FilterOperator
{
    [EnumMember(Value = "eq")]
    Equals,
    [EnumMember(Value = "gt")]
    GreaterThan,
    [EnumMember(Value = "lt")]
    LessThan,
    [EnumMember(Value = "in")]
    In,
    [EnumMember(Value = "like")]
    Like
}

public class GridFilter
{
    [JsonProperty("operator")]
    //[JsonConverter(typeof(StringEnumConverter")] // Remove this
    public FilterOperator Operator { get; set; }
}