JSON.stringify and JSON.parse get different result

Question

I have an Object I use JSON.stringify to create JSON string. Than I save that string into file. Then I read that file. Make JSON.parse and try to use that object again. But it does not work anymore. For example if I use [i] to select element it doesnt select element but just take charset like its a string :(

Can any body help with that?

This is some kind of example but actuall JSON is toooo long:

{"featureCollection":
{"layers":"[
    {\"layerDefinition\": 
        {\"currentVersion\": 10.3,
                         \"id\": 0, 

                                     \"supportsCoordinatesQuantization\": true,
                                     \"advancedQueryCapabilities\": 
                                     {  
                                        \"supportsPagination\": true,

                                        \"supportsDistinct\": true
                                    }, 
                                    \"geometryType\": 
                                        \"esriGeometryPolygon\", \"minScale\": 0,
                                        \"maxScale\": 0,
                                        \"extent\": 
                                            {},
                                        \"drawingInfo\":
                                            {\"renderer\": 
                                                {\"type\": \"simple\", \"symbol\": 
                                                    {\"type\": \"esriSFS\", \"style\": \"esriSFSSolid\", \"color\": [76, 129, 205, 191], \"outline\": 
                                                        {\"type\": \"esriSLS\", \"style\": \"esriSLSSolid\", \"color\": [0, 0, 0, 255], \"width\": 0.75}
                                                    }
                                                },

Can you post the JSON string? or at least a portion of it?

Rob M.
– Rob M.

2015-05-01 23:48:24 +00:00
Commented May 1, 2015 at 23:48 — Rob M.
– Rob M., Commented May 1, 2015 at 23:48
I added in a question

Andriy Sambir
– Andriy Sambir

2015-05-01 23:59:30 +00:00
Commented May 1, 2015 at 23:59 — Andriy Sambir
– Andriy Sambir, Commented May 1, 2015 at 23:59
Solution: Only stringify the root of your data structure.

Felix Kling
– Felix Kling

2015-05-02 00:08:53 +00:00
Commented May 2, 2015 at 0:08 — Felix Kling
– Felix Kling, Commented May 2, 2015 at 0:08

Barmar · Accepted Answer · 2015-05-02 00:05:01Z

4

What's going on is that the layers property of the featureCollection property is not an array, it's a JSON encoding of an array. You need to decode it again to process the contents. Assuming json_obj is the full object, you need to do:

var layers = JSON.parse(json_obj.featureCollection.layers);

Then you can access layers[i].layerDefinition.currentDefinition.

I don't know why it's done that way -- you may want to fix the code that creates the JSON in the first place, and remove the part that calls JSON.stringify() when storing into the layers property.

answered May 2, 2015 at 0:05

Barmar

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1 Comment

Andriy Sambir Over a year ago

Thank you! yes this thing work for me. Firstly I tried to replace escape charset but it didnt work. But anyway thank you a lot!

Rob M. · Accepted Answer · 2015-05-02 00:00:25Z

0

It looks as though the process that is writing the JSON string to a file is escaping the quotes which is causing the issues when you try to parse. You either need to stop the process from escaping the quotes, or use replace to strip out the escaped quotes of your JSON string prior to passing it to parse

answered May 2, 2015 at 0:00

Rob M.

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2 Comments

Barmar Over a year ago

It's not happening when the JSON is being written to the file. Notice that the first two lines aren't escaped.

Rob M. Over a year ago

Good eye, didn't catch that.

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