Does JSON syntax allow duplicate keys in an object?

Question

Is this valid json?

{
    \"a\" : \"x\",
    \"a\" : \"y\"
}

http://jsonlint.com/ says yes.

http://www.json.org/ doesn\'t say anyth

Answer 1

In C# if you deserialise to a Dictionary it takes the last key value pair:

string json = @"{""a"": ""x"", ""a"": ""y""}";
var d = JsonConvert.DeserializeObject>(json);
// { "a" : "y" }

if you try to deserialise to

class Foo
{
    [JsonProperty("a")]
    public string Bar { get; set; }

    [JsonProperty("a")]
    public string Baz { get; set; }
}

var f = JsonConvert.DeserializeObject(json);

you get a Newtonsoft.Json.JsonSerializationException exception.