Side-effects of com.smartgwt.client.util.JSON.encode(jsObj)

[boruvek]

Hello,

I would expect that JSON.encode(jsObj) function that does not modify the object that is passed as a parameter (e.g. it is a function without side-effects).

Using below code I can confirm that some JSON properties are removed from jsObj after calling JSON.encode(jsObj).

To prove this behavior, I created two string representations of the jsObj, that are encoded using pure native JavaScript stringify() function - BEFORE call and AFTER call.
Then I compared these two strings (BEFORE and AFTER) strings and found they are different.
In this case, properties with names like "_recordComponents_isc_CalculationResultGrid" are removed!

GWT.log("BEFORE:" + stringify(jsObj));
String encodedString = JSON.encode(jsObj);
GWT.log("AFTER :" + stringify(jsObj)); 
 private final static native String stringify(JavaScriptObject obj)  /*-{ return JSON.stringify(obj); }-*/;

Properties highlighted in red are removed from jsObj AFTER calling JSON.ecnode(jsObj):

 
 "outputs": [   {     "resultName": "Ref",     ...     "_recordComponents_isc_CalculationResultGrid_0": {        "warnings": {          "isNullMarker": true,          "$669": "isc_CalculationResultGrid_0_body",          "$81x": 1         },    ... }

Isn't this bug?

Is it described somewhere why this happens?

In our case this caused some bug that I can workaround by first creating clone of the jsObj.

Milan

[Isomorphic]

We wouldn't expect this, and we don't see it in basic testing, using your sample snippet with an arbitrary JSO - it's not clear which attributes you're saying are removed (nothing in red) - is it properties that are nested several layers deep, for example, or that have keys prefixed with $?

We expect encode() to simply skip some (internal, eg) properties, not to make any changes to the object itself.

If you can provide a complete test we can run to see the issue, including a full JSO that you're seeing problems with, then we can take another look.

[boruvek]

The "diff" is on the screenshot here:

[Isomorphic]

We've tested this again, as best we can without a test-case - and we still see no issues.

JSON.encode() has no logic to remove properties from an object, so it's difficult to see how a call to it could result in this situation.

Showing a diff doesn't really help us in finding out if there's a bad behavior here - the object you show in the diff appears to be save data from a ListGrid, and there are indeed codepaths that might remove internal ListGrid attributes (like the one you specified) from save-data before sending it to the server - that would be expected behavior, though, since we don't want to send arbitrary widget metadata in save requests.

Please put together a standalone test-case we can run to see the failure - without that, we don't really know where that object is coming from, or what's happening to it before/between your JSON calls.