在工作中见过有的人即便使用了Django，依然还在采取JSON或geojson的文件形式为页面提供数据，相当于嵌入数据而非加载。下面是个简单有效的例子：
先从 model.py 开始
1 # models.py
2 from djanGo.db import models
3
4
5 class Play(models.Model):
6 name = models.CharField(max_length=100)
7 date = models.DateTimeField()urls.py 建立一个 api 的数据（JSON格式）输出路径，另一个给图像输出页面。
1 # urls.py
2 from django.conf.urls import url
3
4
5 from .views import graph, play_count_by_month
6
7 urlpatterns = [
8 url(r'^$', graph),
9 url(r'^api/play_count_by_month', play_count_by_month, name='play_count_by_month'),
10 ]views.py
# views.py
from django.db import connections
from django.db.models import Count
from django.Http import JsonResponse
from django.shortcuts import render
from .models import Play
def graph(request):
return render(request, 'graph/graph.html')
def play_count_by_month(request):
data = Play.objects.all() \
.extra(select={'month': connections[Play.objects.db].ops.date_trunc_sql('month', 'date')}) \
.values('month') \
.annotate(count_items=Count('id'))
return JsonResponse(list(data), safe=False)下面则是HTML部分
1 <!DOCTYPE html>
2 <meta charset="utf-8">
3 <style>
4
5 body {
6 font: 10px sans-serif;
7 }
8
9 .axis path,
10 .axis line {
11 fill: none;
12 stroke: #000;
13 shape-rendering: crispEdges;
14 }
15
16 .x.axis path {
17 display: none;
18 }
19
20 .line {
21 fill: none;
22 stroke: steelblue;
23 stroke-width: 1.5px;
24 }
25
26 </style>
27 <body>
28 <script src="http://d3js.org/d3.v3.js"></script>
29 <script>
30
31 var margin = {top: 20, right: 20, bottom: 30, left: 50},
32 width = 960 - margin.left - margin.right,
33 height = 500 - margin.top - margin.bottom;
34
35 var parseDate = d3.time.fORMat("%Y-%m-%d").parse; // for dates like "2014-01-01"
36 //var parseDate = d3.time.format("%Y-%m-%dT00:00:00Z").parse; // for dates like "2014-01-01T00:00:00Z"
37
38 var x = d3.time.scale()
39 .range([0, width]);
40
41 var y = d3.scale.linear()
42 .range([height, 0]);
43
44 var xAxis = d3.svg.axis()
45 .scale(x)
46 .orient("bottom");
47
48 var yAxis = d3.svg.axis()
49 .scale(y)
50 .orient("left");
51
52 var line = d3.svg.line()
53 .x(function(d) { return x(d.month); })
54 .y(function(d) { return y(d.count_items); });
55
56 var svg = d3.select("body").append("svg")
57 .attr("width", width + margin.left + margin.right)
58 .attr("height", height + margin.top + margin.bottom)
59 .append("g")
60 .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
61
62 d3.json("{% url "play_count_by_month" %}", function(error, data) {
63 data.forEach(function(d) {
64 d.month = parseDate(d.month);
65 d.count_items = +d.count_items;
66 });
67
68 x.domain(d3.extent(data, function(d) { return d.month; }));
69 y.domain(d3.extent(data, function(d) { return d.count_items; }));
70
71 svg.append("g")
72 .attr("class", "x axis")
73 .attr("transform", "translate(0," + height + ")")
74 .call(xAxis);
75
76 svg.append("g")
77 .attr("class", "y axis")
78 .call(yAxis)
79 .append("text")
80 .attr("transform", "rotate(-90)")
81 .attr("y", 6)
82 .attr("dy", ".71em")
83 .style("text-anchor", "end")
84 .text("Play count");
85
86 svg.append("path")
87 .datum(data)
88 .attr("class", "line")
89 .attr("d", line);
90 });
91
92 </script>
93 </body>
94 </html>输出结果，大家可以在admin里调整数据。
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