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POUse @JacksonInject with @JsonCreator on a top level map
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copied!<p>With Jackson json library, it is possible to deserialize object through the use of the <code>@JsonCreator</code>, and be given the "top level" map representing the input json, as follows:</p> <pre class="lang-java prettyprint-override"><code>class MyClass { final int field; @JsonCreator public MyClass(Map<String, Object> map) { this.field = (int) map.get("theInt"); } } </code></pre> <p>or even on a static factory method:</p> <pre class="lang-java prettyprint-override"><code>class MyClass { final int field; public MyClass(int theInt) { this.field = theInt; } @JsonCreator static MyClass create(Map<String, Object> map) { return new MyClass((int) map.get("theInt")); } } </code></pre> <p>The previous examples can process the following kind of json input:</p> <pre class="lang-json prettyprint-override"><code>{ "key1":"value1", "key2":"value2", "key3":"value3" } </code></pre> <p>This is particularly useful in my case because I would like to deserialize a json which structure I don't know. Being given access to what I call the "top level map" makes things simple.</p> <p>I would like to deserialize my objects this way as it also allows to create immutable objects, instead of using <code>@JsonAnySetter</code> which doesn't permit this, and <code>@JsonProperty</code> which I can't use as I don't know the properties name in advance as I mentioned earlier.</p> <p>Then to go further, I would like to inject some configuration in my factory method, and Jackson allows this through the use of <code>@JacksonInject</code> and a call to <code>withInjectableValues(InjectableValues)</code> on the <code>ObjectMapper</code>.</p> <p>This is eventually the kind of code I would like to use:</p> <pre class="lang-java prettyprint-override"><code>class MyClass { final MyField[] myFields; public MyClass(MyField... myFields) { this.myFields = myFields; } @JsonCreator static MyClass create(@JacksonInject("conf") Conf conf, Map<String, Object> map) { MyFields[] myFields; // initialize myFields (or any other object) based on the content of map // and also make use of the inject conf return new MyClass(myFields); } } </code></pre> <p>Unfortunately, Jackson throws the following kind of exceptions:</p> <ul> <li>when trying the trick on the constructor</li> </ul> <p><code>JsonMappingException: Argument #1 of constructor [constructor for MyClass, annotations: {JsonCreator=@JsonCreator()}] has no property name annotation; must have name when multiple-paramater constructor annotated as Creator</code></p> <ul> <li>when trying the trick on the factory method</li> </ul> <p><code>JsonMappingException: Argument #1 of factory method [method create, annotations: {JsonCreator=@JsonCreator()}] has no property name annotation; must have when multiple-paramater static method annotated as Creator</code></p> <p>Does anyone know how I could solve the problem?</p> <p>To sum up the requirements, I need:</p> <ul> <li>access to the top level map (don't know the json property names in advance)</li> <li>to create an immutable object (so can't use <code>@JsonAnySetter</code>)</li> <li>to inject some conf to the <code>@JsonCreator</code> decorated constructor or factory method</li> </ul> <p>I cannot change the json input format, which looks like this:</p> <pre class="lang-json prettyprint-override"><code>{ "key1":"value1", "key2":"value2", "key3":"value3" } </code></pre> <p>[EDIT]</p> <p>This is a known issue: <a href="http://jira.codehaus.org/browse/JACKSON-711" rel="noreferrer">http://jira.codehaus.org/browse/JACKSON-711</a> (not fixed yet)</p>

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