James Newton-King

Archives

Archives / 2014 / February
  • Feb 1 2014

    Json.NET 6.0 Release 1 - JSONPath and F# Support

    JSONPath

    Json.NET has supported basic path queries with SelectToken since forever. Json.NET 6.0 supes up SelectToken with full support for JSONPath, an XPath like querying language for JSON.

    JObject o = JObject.Parse(@"{
      ""Manufacturers"": [
        {
          ""Name"": ""Acme Co"",
          ""Products"": [
            {
              ""Name"": ""Anvil"",
              ""Price"": 50
            }
          ]
        },
        {
          ""Name"": ""Contoso"",
          ""Products"": [
            {
              ""Name"": ""Elbow Grease"",
              ""Price"": 99.95
            },
            {
              ""Name"": ""Headlight Fluid"",
              ""Price"": 4
            }
          ]
        }
      ]
    }");
     
    // manufacturer with the name 'Acme Co'
    var acme = o.SelectToken("$.Manufacturers[?(@.Name == 'Acme Co')]");
     
    Console.WriteLine(acme);
    // { "Name": "Acme Co", Products: [{ "Name": "Anvil", "Price": 50 }] }

    A SelectTokens (plural) method has been added for returning a range of results from a JSONPath query.

    // name of all products priced 50 and above
    var pricyProducts = o.SelectTokens("$..Products[?(@.Price >= 50)].Name");
     
    Console.WriteLine(pricyProducts);
    // Anvil
    // Elbow Grease

    While LINQ to JSON offers more features and flexibility, JSONPath being string based makes it a good choice for persisting a queries or constructing dynamic queries.

    F# Support

    Json.NET 6.0 adds support for serializing and deserializing F# discriminated unions. There is nothing you need to do, F# discriminated unions will now Just Work.

    type Shape =
        | Rectangle of width : float * length : float
        | Circle of radius : float
        | Empty
     
    [<EntryPoint>]
    let main argv = 
     
        let shape1 = Rectangle(1.3, 10.0)
     
        let json = JsonConvert.SerializeObject(shape1)
        // {
        //   "Case": "Rectangle",
        //   "Fields": [
        //     1.3,
        //     10.0
        //   ]
        // }
     
        let shape2 = JsonConvert.DeserializeObject<Shape>(json)
     
        Console.ReadKey() |> ignore
        0

    Assembly Version Happenings

    Json.NET has had a static assembly version since 4.5 to avoid binding redirects. The problem with having a static assembly version is if a strongly named assembly with the same version number is found in the GAC, the GAC version will be used ahead for the /bin version. Some people have been encountering the problem that their applications break when someone else GACs an old Json.NET 4.5 on their server. I’m looking at you .NET CMSes.

    The plan going forward is to increase the assembly version with major Json.NET releases. 6.0 Release 1 –> 6.0.0.0, 6.0 Release 2 –> 6.0.0.0, 7.0 Release 1 –> 7.0.0.0. Hopefully this will provide a balance between binding redirects and having the GAC ruin your day.

    And The Rest

    Tons of smaller features like parsing single line comments in JSON, reading multiple pieces of JSON content from a stream with one JsonReader, obsoleting of bad methods and lots of bug fixes.

    Changes

    Here is a complete list of what has changed since Json.NET 5.0 Release 8.

    • New feature - Added support for JSONPath
    • New feature - Added support for serializing F# discriminated unions
    • New feature - Added support for deserializing nested DataTables and arrays in DataTables
    • New feature - Added support for reading multiple pieces of JSON with a JsonReader
    • New feature - Added AllowIntegerValues setting to StringEnumConverter
    • New feature - Added Decimal and DateTimeOffset constructors to JValue
    • New feature - Added support for reading JSON single line comments
    • New feature - Improved number parsing error messages
    • Change - Changed assembly version to 6.0.0.0
    • Change - .NET 4 Portable build targets MonoTouch and MonoDroid in NuGet package
    • Change - .NET 4 Portable build targets WP8 and SL5 instead of WP7 and SL4
    • Removed - DefaultMemberSearchFlags on DefaultContractResolver is obsolete
    • Removed - SerializeObjectAsync, DeserializeObjectAsync, PopulateObjectAsync on JsonConvert are obsolete
    • Fix - Fixed JObject ICustomTypeDescriptor properties returning incorrect value
    • Fix - Fixed error when casting dynamic base64 string to byte array
    • Fix - Fixed EntityKeyMemberConverter not using property name resolve
    • Fix - Fixed serializing JValues with readonly JsonConverters
    • Fix - Fixed formatting override on SerializeObject methods
    • Fix - Fixed error when wrapping an exception in a JsonConverter
    • Fix - Fixed using extension data with a non-default constructor
    • Fix - Fixed Uri serialization roundtripping with Uri.OriginalString
    • Fix - Fixed TypeNameHandling.Auto with JsonSerializer.Serialize inside a JsonConverter

    Links

    Json.NET GitHub Project

    Json.NET 6.0 Release 1 Download - Json.NET source code and assemblies