d3js returning “[object%20Object]” and “Uncaught TypeError: Cannot read property: nodes of undefined”

余生颓废 提交于 2019-12-12 16:22:33

问题


I am new to Javascript and Django. I have to animate a svg file with D3js, so to practice and understand how it works I decided to add the miserables widget to my local Django website. I have a simple view:

def miserable(request):
    return render_to_response('index.html')

The url is: url(r'^moremiser/$','more_miserable')and I copied both index.html and miserable.json into my template folder. When I go to the url that is supposed to display the widget all I get is a blank screen. what am I doing wrong? The person who set up the local website installed tinymce and compressor, could they be causing the problem? here is the code for index.html and miserables.json. They both are in my templates folder:

#index.html       
<!DOCTYPE html>
    <meta charset="utf-8">
    <style>

    .node {
      stroke: #fff;
      stroke-width: 1.5px;
    }

    .link {
      stroke: #999;
      stroke-opacity: .6;
    }

    </style>
    <body>
    <script src="http://d3js.org/d3.v3.min.js"></script>
    <script>

    var width = 960,
        height = 500;

    var color = d3.scale.category20();

    var force = d3.layout.force()
        .charge(-120)
        .linkDistance(30)
        .size([width, height]);

    var svg = d3.select("body").append("svg")
        .attr("width", width)
        .attr("height", height);

    d3.json("miserables.json", function(error, graph) {
      force
          .nodes(graph.nodes)
          .links(graph.links)
          .start();

      var link = svg.selectAll(".link")
          .data(graph.links)
        .enter().append("line")
          .attr("class", "link")
          .style("stroke-width", function(d) { return Math.sqrt(d.value); });

      var node = svg.selectAll(".node")
          .data(graph.nodes)
        .enter().append("circle")
          .attr("class", "node")
          .attr("r", 5)
          .style("fill", function(d) { return color(d.group); })
          .call(force.drag);

      node.append("title")
          .text(function(d) { return d.name; });

      force.on("tick", function() {
        link.attr("x1", function(d) { return d.source.x; })
            .attr("y1", function(d) { return d.source.y; })
            .attr("x2", function(d) { return d.target.x; })
            .attr("y2", function(d) { return d.target.y; });

        node.attr("cx", function(d) { return d.x; })
            .attr("cy", function(d) { return d.y; });
      });
    });

</script>

#miserables.json
{
  "nodes":[
    {"name":"Myriel","group":1},
    {"name":"Napoleon","group":1},
    {"name":"Mlle.Baptistine","group":1},
    {"name":"Mme.Magloire","group":1},
    {"name":"CountessdeLo","group":1},
    {"name":"Geborand","group":1},
    {"name":"Champtercier","group":1},
    {"name":"Cravatte","group":1},
    {"name":"Count","group":1},
    {"name":"OldMan","group":1},
    {"name":"Labarre","group":2},
    {"name":"Valjean","group":2},
    {"name":"Marguerite","group":3},
    {"name":"Mme.deR","group":2},
    {"name":"Isabeau","group":2},
    {"name":"Gervais","group":2},
    {"name":"Tholomyes","group":3},
    {"name":"Listolier","group":3},
    {"name":"Fameuil","group":3},
    {"name":"Blacheville","group":3},
    {"name":"Favourite","group":3},
    {"name":"Dahlia","group":3},
    {"name":"Zephine","group":3},
    {"name":"Fantine","group":3},
    {"name":"Mme.Thenardier","group":4},
    {"name":"Thenardier","group":4},
    {"name":"Cosette","group":5},
    {"name":"Javert","group":4},
    {"name":"Fauchelevent","group":0},
    {"name":"Bamatabois","group":2},
    {"name":"Perpetue","group":3},
    {"name":"Simplice","group":2},
    {"name":"Scaufflaire","group":2},
    {"name":"Woman1","group":2},
    {"name":"Judge","group":2},
    {"name":"Champmathieu","group":2},
    {"name":"Brevet","group":2},
    {"name":"Chenildieu","group":2},
    {"name":"Cochepaille","group":2},
    {"name":"Pontmercy","group":4},
    {"name":"Boulatruelle","group":6},
    {"name":"Eponine","group":4},
    {"name":"Anzelma","group":4},
    {"name":"Woman2","group":5},
    {"name":"MotherInnocent","group":0},
    {"name":"Gribier","group":0},
    {"name":"Jondrette","group":7},
    {"name":"Mme.Burgon","group":7},
    {"name":"Gavroche","group":8},
    {"name":"Gillenormand","group":5},
    {"name":"Magnon","group":5},
    {"name":"Mlle.Gillenormand","group":5},
    {"name":"Mme.Pontmercy","group":5},
    {"name":"Mlle.Vaubois","group":5},
    {"name":"Lt.Gillenormand","group":5},
    {"name":"Marius","group":8},
    {"name":"BaronessT","group":5},
    {"name":"Mabeuf","group":8},
    {"name":"Enjolras","group":8},
    {"name":"Combeferre","group":8},
    {"name":"Prouvaire","group":8},
    {"name":"Feuilly","group":8},
    {"name":"Courfeyrac","group":8},
    {"name":"Bahorel","group":8},
    {"name":"Bossuet","group":8},
    {"name":"Joly","group":8},
    {"name":"Grantaire","group":8},
    {"name":"MotherPlutarch","group":9},
    {"name":"Gueulemer","group":4},
    {"name":"Babet","group":4},
    {"name":"Claquesous","group":4},
    {"name":"Montparnasse","group":4},
    {"name":"Toussaint","group":5},
    {"name":"Child1","group":10},
    {"name":"Child2","group":10},
    {"name":"Brujon","group":4},
    {"name":"Mme.Hucheloup","group":8}
  ],
  "links":[
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  ]
}

When I open the Javascript debugger in Google Chrome, I see that instead of going to the url "moremiser" the server try to go to "moremiser/[object%20Object] and then the other error message appears:""Uncaught TypeError: Cannot read property: nodes of undefined". What should I modify?


回答1:


Yes, I did. I think Javascript cannot locate "miserable.json" nor access the nodes in it. I say this because I have assigned the content of "miserables.json" to an object defined into "index.html" without success. Then, I created an array of nodes(without identifying them as being node), pasted the code for the array into the "index.html" file, and wrote a for loop printing as many "hello wolrd" as there are objects in the array; at first, the browser said that d3 was not defined, then it worked when I referenced the url of the online d3 library instead of the d3 folder on my computer.

 <!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <title>D3 Test</title>
        <script type="text/javascript" src="http://d3js.org/d3.v3.min.js"></script>
    </head>
    <body>
        <script type="text/javascript">
var dataset = [{"name":"Myriel","group":1},
    {"name":"Napoleon","group":1},
    {"name":"Mlle.Baptistine","group":1},
    {"name":"Mme.Magloire","group":1},
    {"name":"CountessdeLo","group":1},
    {"name":"Geborand","group":1},
    {"name":"Champtercier","group":1},
    {"name":"Cravatte","group":1},
    {"name":"Count","group":1},
    {"name":"OldMan","group":1},
    {"name":"Labarre","group":2},
    {"name":"Valjean","group":2},
    {"name":"Marguerite","group":3},
    {"name":"Mme.deR","group":2},
    {"name":"Isabeau","group":2},
    {"name":"Gervais","group":2},
    {"name":"Tholomyes","group":3},
    {"name":"Listolier","group":3},
    {"name":"Fameuil","group":3},
    {"name":"Blacheville","group":3},
    {"name":"Favourite","group":3},
    {"name":"Dahlia","group":3},
    {"name":"Zephine","group":3},
    {"name":"Fantine","group":3},
    {"name":"Mme.Thenardier","group":4},
    {"name":"Thenardier","group":4},
    {"name":"Cosette","group":5},
    {"name":"Javert","group":4},
    {"name":"Fauchelevent","group":0},
    {"name":"Bamatabois","group":2},
    {"name":"Perpetue","group":3},
    {"name":"Simplice","group":2},
    {"name":"Scaufflaire","group":2},
    {"name":"Woman1","group":2},
    {"name":"Judge","group":2},
    {"name":"Champmathieu","group":2},
    {"name":"Brevet","group":2},
    {"name":"Chenildieu","group":2},
    {"name":"Cochepaille","group":2},
    {"name":"Pontmercy","group":4},
    {"name":"Boulatruelle","group":6},
    {"name":"Eponine","group":4},
    {"name":"Anzelma","group":4},
    {"name":"Woman2","group":5},
    {"name":"MotherInnocent","group":0},
    {"name":"Gribier","group":0},
    {"name":"Jondrette","group":7},
    {"name":"Mme.Burgon","group":7},
    {"name":"Gavroche","group":8},
    {"name":"Gillenormand","group":5},
    {"name":"Magnon","group":5},
    {"name":"Mlle.Gillenormand","group":5},
    {"name":"Mme.Pontmercy","group":5},
    {"name":"Mlle.Vaubois","group":5},
    {"name":"Lt.Gillenormand","group":5},
    {"name":"Marius","group":8},
    {"name":"BaronessT","group":5},
    {"name":"Mabeuf","group":8},
    {"name":"Enjolras","group":8},
    {"name":"Combeferre","group":8},
    {"name":"Prouvaire","group":8},
    {"name":"Feuilly","group":8},
    {"name":"Courfeyrac","group":8},
    {"name":"Bahorel","group":8},
    {"name":"Bossuet","group":8},
    {"name":"Joly","group":8},
    {"name":"Grantaire","group":8},
    {"name":"MotherPlutarch","group":9},
    {"name":"Gueulemer","group":4},
    {"name":"Babet","group":4},
    {"name":"Claquesous","group":4},
    {"name":"Montparnasse","group":4},
    {"name":"Toussaint","group":5},
    {"name":"Child1","group":10},
    {"name":"Child2","group":10},
    {"name":"Brujon","group":4},
    {"name":"Mme.Hucheloup","group":8}];

d3.select("body").selectAll("p")
    .data(dataset)
    .enter()
    .append("p")
    .text("New paragraph!")
        </script>
    </body>
</html>


来源:https://stackoverflow.com/questions/15162290/d3js-returning-object20object-and-uncaught-typeerror-cannot-read-property

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