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Parsing list of lists in jQuery

in Using jQuery • 6 years ago

I have a list of lists (e.g. [[1,2],[3,4]]) passed from a Django view, stored in a hidden input of an html form, and submitted with jQuery. I need to parse that variable to pull indices. I have other lists passed between Django and html without a problem, but this list is posted by jQuery.

HTML:

<input type="hidden" name="resultMsgList" id="resultMsgList" value="[[&#39;View &quot;S03_2005_TAZ_140813_160946_with_geom&quot; was successfully created!&#39;, &#39;taz_mapfile_scen_tdm_140813_160946&#39;, &#39;S03_2005_TAZ_140813_160946_with_geom&#39;, &#39;C:/djangoProjects/web_output/mapfiles/ATLANTA/taz_mapfile_scen_tdm_140813_160946.map&#39;, [25, 50, 13.8926482138839, 44488.7998645071]]]"/>

Javascript:

var resultMsgList = $("#resultMsgList").val();

var data = {'resultMsgList':resultMsgList};

$.post(URL, data, function(result){

mapDataHtml = $(result).find("#mapData").html();

$("#mapData").html(mapDataHtml); });

I don't technically need the last 2 lines of code anymore, but it's not affecting my testing.

The post data from jQuery output to the Google console is: resultMsgList = u'[[\'View "S03_2010_TAZ_140813_112333_with_geom" was successfully created!\', \'taz_mapfile_scen_tdm_140813_112333\', \'S03_2010_TAZ_140813_112333_with_geom\', \'C:/djangoProjects/web_output/mapfiles/ATLANTA/taz_mapfile_scen_tdm_140813_112333.map\', [25, 50, 10.8820127624776, 49619.5163142776]]]'

It is currently giving me "String index out of range" and an error at

jquery-1.10.2.js:8706 so I think jQuery is viewing it as a string.

Replies(4)

watusiware

Re: Parsing list of lists in jQuery

6 years ago

Can you clean up your code so that it is human-readable?

It isn't very useful to post your Python code (or any other server language code, for that matter). Can you please post the HTML that it generates? That's what jQuery gets to work with. It does't know or care how you create it on your server.

watusiware

Re: Parsing list of lists in jQuery

6 years ago

jQuery has nothing to do with it.

Javascript thinks it's a string because it is one. What did you think it was? Input values are strings.

The only "magic parsing of JSON" by jQuery is:

- in $.ajax() (if the server has set the right Mime type or if you specify it explicitly and in data- attributes.

- jQuery will parse JSON if it find valid JSON in a data- attribute, and then you can just access the Javascript object with $('.some-selector).data().

If you want to parse that string and create a Javascript object you'll have to do so yourself, using JSON.parse().

I don't know what u' means.

Jason Haw..

Re: Parsing list of lists in jQuery

6 years ago

u' is what the Google Chrome development panel prepends to signify the variable is a unicode string.

I reconfigured my code so resultMsgList is passed directly to javascript. I pre-process the data to JSON with json.dumps() in python. The javascript variable is:

var resultMsgList = [[ "View \"S03_2005_LUZ_140814_105049_with_geom\" was successfully created!" , "luz_mapfile_scen_tdm_140814_105049" , "S03_2005_LUZ_140814_105049_with_geom" , "C:/djangoProjects/web_output/mapfiles/ATLANTA/luz_mapfile_scen_tdm_140814_105049.map" , [ 25 , 50 , 498.26708421479 , 131137.057816715 ]]];

This works and I have confirmed it is correct syntax using a validator (http://jsonformatter.curiousconcept.com/). I should then have to convert it from JSON to a python list using json.loads(), but I get an error stating there isn't a valid JSON object. I confirmed the formatting in the python docs.

The post appears in the header panel on the Chrome panel as:

resultMsgList[0][]:View "S03_2005_LUZ_140814_105049_with_geom" was successfully created!
resultMsgList[0][]:luz_mapfile_scen_tdm_140814_105049
resultMsgList[0][]:S03_2005_LUZ_140814_105049_with_geom
resultMsgList[0][]:C:/djangoProjects/web_output/mapfiles/ATLANTA/luz_mapfile_scen_tdm_140814_105049.map
resultMsgList[0][4][]:25
resultMsgList[0][4][]:50
resultMsgList[0][4][]:498.26708421479
resultMsgList[0][4][]:131137.057816715

watusiware

Re: Parsing list of lists in jQuery

6 years ago

Well, now you have the opposite problem.

resultMsgList is not a string. It's a Javascript list of lists.

JSON is a string representation of a data structure. If you want to send JSON to your server, you need to convert your list of lists to a string with JSON representation. You can do that with JSON.stringify()

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