mar*_*lle 8 postgresql node.js express d3.js
我构建了一个Node.js应用程序,它从Internet上删除一些信息并将这些信息保存在postgreSQL数据库中.现在我想使用D3.js创建一些可视化.通常我使用.csv文件创建可视化,但现在我想从我的数据库中获取数据.
我想用Express.js.这是我的代码,它可以工作,但它从.csv文件中获取数据,而不是从数据库获取数据.
app.js:
const express = require('express');
var app = express();
const start = async function() {
console.log('\n(1) Connect to db');
await postgreSQLlib.connect();
console.log('\n(02) Create tables if they do not exist');
await postgreSQLlib.createTables();
console.log('\n(03) Check if table \'example\' is updated or not');
if(!await utilFunc.isTableUpdated('example', 6308)) {
console.log('\n (04) Download data for coverages');
await downloader.download();
console.log('\n (05) Elaborate data for example before to save on DB');
await elaborate.elaborate();
console.log('\n (06) Saving data on db');
await saveOnDb.save();
}
console.log('\n(10) D3js visualizations');
app.set('port', process.env.PORT || 300)
var server = app.listen(app.get('port'), function() {
console.log('Listening on PORT: ' + app.get('port'));
});
app.use('/',express.static('public/donut'))
// I can't disconnect from db if I have to show visualizations, am I right?
console.log('\n(11) Disconnect');
await postgreSQLlib.disconnect();
}
start()
.then(function(res) {
console.log('Done');
})
.catch(function(err) {
console.log(err);
});
index.html:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Donut</title>
<script src="https://d3js.org/d3.v3.min.js" charset="utf-8"></script>
<link rel="stylesheet" type="text/css" href="./donut.css" media="screen"/>
</head>
<body>
<script src="./donut.js"></script>
</body>
</html>
donut.js:
var width = 960,
height = 500,
radius = Math.min(width, height) / 2;
var color = d3.scale.ordinal()
.range(["#98abc5", "#8a89a6", "#7b6888", "#6b486b", "#a05d56", "#d0743c", "#ff8c00"]);
var arc = d3.svg.arc()
.outerRadius(radius - 10)
.innerRadius(radius - 70);
var pie = d3.layout.pie()
.sort(null)
.value(function(d) { return d.population; });
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");
d3.csv("./data.csv", type, function(error, data) {
if (error) throw error;
var g = svg.selectAll(".arc")
.data(pie(data))
.enter().append("g")
.attr("class", "arc");
g.append("path")
.attr("d", arc)
.style("fill", function(d) { return color(d.data.age); });
g.append("text")
.attr("transform", function(d) { return "translate(" + arc.centroid(d) + ")"; })
.attr("dy", ".35em")
.text(function(d) { return d.data.age; });
});
function type(d) {
d.population = +d.population;
return d;
}
data.csv:
age,population
<5,2704659
5-13,4499890
14-17,2159981
18-24,3853788
25-44,14106543
45-64,8819342
?65,612463
我也尝试:
const start = async function() {
//...
function onRequest(req, res) {
if(req.method == 'GET' && req.url == '/') {
var client = new pg.Client(conString);
client.connect();
var query = client.query('SELECT * FROM example;');
query.on('row', function(row, result) {
result.addRow(row);
});
query.on('end', function(result) {
res.status(200)
res.json(result.rows);
client.end();
});
}
}
}
和:
d3.csv("/", type, function(error, data) {
if(error) {
throw error;
}
console.log('data:', data);
...
}
但它不起作用.
我不会使用.csv文件来存储我的数据,但我想使用db.我怎样才能做到这一点？