yajl 0.2.0

YAJL, Yet Another JSON library, binding for D.

To use this package, put the following dependency into your project's dependencies section:


YAJL binding for D

yajl-d is a YAJL binding for D.

yajl-d is based on YAJL and work on 2.1.0 or later.


Add yajl to dependencies of package.json.

  "dependencies": {
    "yajl": ">=0.2.0"

Run example

Need to link yajl library

dmd -Isrc src/**/*.d -L-lyajl -run example/encode_bench.d



  • yajl.encode(value) / yajl.encode(value, opt)

import yajl;

struct Hoge
    ulong id;
    string word;
    bool yes; 

// {"id":100,"word":"hey!","yes":true}
string json = encode(Hoge(100, "hey!", true));


  • yajl.decode(value) / yajl.decode(value, opt)

import yajl;

Hoge hoge = decode!Hoge(`{"id":100,"word":"hey!","yes":true}`);
  • yajl.decoder.Decoder

Use decode and decodedValue methods.

import yajl.decoder;

Decoder decoder;
if (decoder.decode(`{"id":100,"word":"hey!","yes":true}`) {
    Hoge hoge = decoder.decodedValue!Hoge;
    // ...

Decoder#decode is a straming decoder, so you can pass the insufficient json to this method. If Decoder#decode can't parse completely, Decoder#decode returns false.

Encoder.Option and Decoder.Option

encode and decode can take each Option argument. If you want to know more details, see unittest of yajl.encoder / yajl.decoder.

Set callback to detect missing field

You can set own callback to Decoder.Option.missingHandler. Here is an example:

import yajl;
import std.stdio;

struct Test
  string name;
  int age;

void main()
  auto test = Test("Bob", 20);
  auto encoded = `{ "name": "Bob", "age": 20}`;
  auto missing = `{ "name": "Bob"}`;

  Decoder.Option opt;
  opt.missingHandler = (string field) { writeln(field); };
  writeln(decode!Test(encoded, opt));
  writeln(decode!Test(missing, opt)); // Callback called with missing field

Using a D keyword in JSON field names

Since a field name cannot be a D keyword, for example body or out, the variable and JSON field must have separate names. For this, use the @JSONName("name") attribute:

import yajl;

struct Hoge
    ulong id;
    @JSONName("body") string _body;
    bool yes; 

// {"id":100,"body":"hey!","yes":true}
string json = encode(Hoge(100, "hey!", true));


D: dmd 2.066.0<br /> yajl: 2.1.0<br /> OS: Mac OS X ver 10.9<br /> CPU: 2.6 GHz Intel Core i7<br />

<table> <tr>

<th></th><th>encode(QPS)</th><th>multi encode(QPS)</th><th>decode(QPS)</th><th>multi decode(QPS)</th>

</tr> <tr>

<td>std.json</td><td>262272</td><td>Not supported</td><td>287072</td><td>Not supported</td>

</tr> <tr>


</tr> </table>

Benchmark code can be found in the example directory.


  • Limited direct conversion decoding
  • Test on Windows

YAJL official site

Github repository

<table> <tr>

<td>Author</td><td>Masahiro Nakagawa <repeatedly@gmail.com></td>

</tr> <tr>

<td>Copyright</td><td>Copyright (c) 2013- Masahiro Nakagawa</td>

</tr> <tr>

<td>License</td><td>Boost Software License, Version 1.0</td>

</tr> </table>

Masahiro Nakagawa
0.2.0 2014-Oct-04
0.1.2 2014-Oct-02
0.1.1 2014-Sep-28
0.1.0 2014-Sep-22
~master 2014-Oct-04
Show all 5 versions
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