JavaScript/GSON: Access JSON references dynamically over object graph (circular references)

问题

I had the problem, to serialize my Java objects through Google GSON, because of several circular references. All my tries ended up in a StackOverflowException, because GSON is not able to handle those circular references.

As a solution, I found following GraphAdapterBuilder:

http://code.google.com/p/google-gson/source/browse/trunk/extras/src/main/java/com/google/gson/graph/GraphAdapterBuilder.java?r=1170

Example: https://groups.google.com/forum/#!topic/google-gson/z2Ax5T1kb2M

{
  "0x1": {
    "name": "Google",
    "employees": [
      "0x2",
      "0x3"
    ]
  },
  "0x2": {
    "name": "Jesse",
    "company": "0x1"
  },
  "0x3": {
    "name": "Joel",
    "company": "0x1"
  }
}

This is working very well, but I am still not able to access the reference values (0xn) dynamically over the object graph like:

alert(0x3.company.name); --> Should print "Google", but I only receive undefined

Is it somehow possible to achieve this?

Maybe with a custom JSON.parse(ajaxResponse, function(key,value) {} function which replaces the variable with the referenced object tree?

回答1:

!! UPDATE, BETTER SOLUTION !!

If you can switch your library, just use FlexJson >>> http://flexjson.sourceforge.net/.

I solved my problem with an own JSON parser:

"ref" is "0x[n]" in the original GraphAdapterBuilder

Source:

$.ajax({
    type: "POST",
    url: "controller/ajaxmethod.htm",
    data: { "var1": var1, "var2":var2},
    success: function(response){
    var jsonObject = parseGraphGSON(response, 0);
            ...
    },
    error: function(e){
          alert('Error: ' + e.status);
    }
});


function parseGraphGSON(gsonResponse, recursionLevel) {
    var maxRecursionDepth = 2;
    var jsonObject = JSON.parse(gsonResponse, function(key, value) {
        if (typeof value === 'string') {
            if (value.indexOf("ref") == 0) {
                if (recursionLevel < maxRecursionDepth) {
                    return parseGraphGSON(gsonResponse, recursionLevel + 1)[value];
                } else {
                    return JSON.parse(gsonResponse)[value];
                    }
            }
        }
        return value;
    });
    return jsonObject;
}

回答2:

For future users, refer to this answer which uses GraphAdapterBuilder: https://stackoverflow.com/a/10046134/1547266

来源：https://stackoverflow.com/questions/22777930/javascript-gson-access-json-references-dynamically-over-object-graph-circular

标签

javascript

json

serialization

gson

circular-reference