从JSON字符串而不是JSON文件中渲染D3图形 [英] Render D3 graph from a string of JSON instead of a JSON file

问题描述

我想从我的Rails应用程序呈现以下Dendrogram：
http：// bl .ocks.org / mbostock / 4063570

I am trying to render the following Dendrogram from my Rails app: http://bl.ocks.org/mbostock/4063570

我有一个有许多属性的模型，但我想手动嵌套这些属性，只需使用字符串插值建立自己的JSON字符串，然后直接传递给d3。

I have a model with many attributes, but I would like to manually nest those attributes and simply use string interpolation to build up my own JSON string, then pass that to d3 directly.

这是我的代码：

    <%= javascript_tag do %>
        var width = 960,
        height = 2200;

        var cluster = d3.layout.cluster()
        .size([height, width - 160]);

        var diagonal = d3.svg.diagonal()
        .projection(function(d) { return [d.y, d.x]; });

        var svg = d3.select("body").append("svg")
        .attr("width", width)
        .attr("height", height)
        .append("g")
        .attr("transform", "translate(40,0)");

        **d3.json("/assets/flare.json", function(root) {**
        var nodes = cluster.nodes(root),
        links = cluster.links(nodes);

        var link = svg.selectAll(".link")
        .data(links)
        .enter().append("path")
        .attr("class", "link")
        .attr("d", diagonal);

        var node = svg.selectAll(".node")
        .data(nodes)
        .enter().append("g")
        .attr("class", "node")
        .attr("transform", function(d) { return "translate(" + d.y + "," + d.x + ")"; })

        node.append("circle")
        .attr("r", 4.5);

        node.append("text")
        .attr("dx", function(d) { return d.children ? -8 : 8; })
        .attr("dy", 3)
        .style("text-anchor", function(d) { return d.children ? "end" : "start"; })
        .text(function(d) { return d.name; });
        });

        d3.select(self.frameElement).style("height", height + "px");
    <% end %>

这是我的（未分级）JSON字符串：

Here is my (unminified) JSON string:

var mystring = '{
    "name": "Product",
    "properties": {
        "id": {
            "type": "number",
            "description": "Product identifier",
            "required": true
        },
        "name": {
            "type": "string",
            "description": "Name of the product",
            "required": true
        },
        "price": {
            "type": "number",
            "minimum": 0,
            "required": true
        },
        "tags": {
            "type": "array",
            "items": {
                "type": "string"
            }
        },
        "stock": {
            "type": "object",
            "properties": {
                "warehouse": {
                    "type": "number"
                },
                "retail": {
                    "type": "number"
                }
            }
        }
    }
}';

我尝试的东西：

2）在字符串上运行JSON.parse（mystring）

2) running JSON.parse(mystring) on the string

3）查看D3文档和googling一个方法修改以下函数接受一个字符串而不是文件路径：
d3.json（/ assets / flare。 json，function（root）{
var nodes = cluster.nodes（root），
links = cluster.links（nodes）;

3) looking through the D3 documentation and and googling for a way to modify the following function to accept a string instead of a file path: d3.json("/assets/flare.json", function(root) { var nodes = cluster.nodes(root), links = cluster.links(nodes);

推荐答案

首先，让我们看看 d3.json 是什么。

First, lets look at what d3.json does.

d3.json("/assets/flare.json", function(root) {
    // code that uses the object 'root'
});

这将加载文件 /assets/flare.json 服务器将内容解释为JSON，并将作为 root 参数的结果对象传递给匿名函数。

This loads the file /assets/flare.json from the server, interprets the contents as JSON and passes the resulting object as the root argument to the anonymous function.

如果你已经有一个JSON对象，你不需要使用 d3.json 函数 - 你可以直接使用对象。

Where you already have a JSON object, you don't need to use the d3.json function - you can just use the object directly.

var root = {
   "name": "flare",
   "children": [
     ...
   ]
};
// code that uses the object 'root'

如果对象表示为字符串，那么您可以使用 JSON.parse 获取对象：

If the object is represented as a string, then you can use JSON.parse to get the object:

var myString = '{"name": "flare","children": [ ... ] }';
var root = JSON.parse(mystring);
// code that uses the object 'root'

其次， code> d3.layout.cluster 期望您的数据。根据文档：

Second, lets look at what d3.layout.cluster expects of your data. As per the docs:

...默认的子访问器假设每个输入数据都是一个带有子数组的对象...

... the default children accessor assumes each input data is an object with a children array ...

换句话说，你的数据需要是以下形式：

In other words, you data needs to be of the form:

var mystring = '{
    "name": "Product",
    "children": [
        {
            "name": "id",
            "type": "number",
            "description": "Product identifier",
            "required": true
        },
        ...
        {
            "name": "stock",
            "type": "object",
            "children": [
                {
                    "name: "warehouse",
                    "type": "number"
                },
                {
                    "name": "retail",
                    "type": "number"
                }
            ]
        }
    ]
}

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