我一直致力于构建REST API。 API的目的是以.JSON格式在本地服务器上显示有关太阳系中行星的信息。我使用Postman测试URL（localhost:8000/planets）。我可以发出GET请求，但我遇到POST请求有问题。
我继续邮递员，输入localhost:8000/planets并发出GET请求以显示我的信息。然后我将请求类型更改为POST，然后按发送。然后点击＆＃39; Body＆＃39;，选择＆＃39; Raw＆＃39;然后从＆＃39;文本＆＃39;更改格式到＆＃39; JSON（application / json）。
然后我输入要添加到数据库的数据，然后按SEND。现在，当我做第二个GET请求时，我可以看到刚发布的数据。但是，如果我修改了保存POST和GET请求等代码的JavaScript文件......然后在Postman上做第三个GET请求，我刚发布的数据就会从数据库中消失。我对这一切都很陌生，但我认为这不应该发生。如果出现问题，我确定它必须在我的代码中。我的代码是：
var express = require('express');
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
var app = express();
app.use(express.static('public'));
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
mongoose.Promise = global.Promise;
var promise = mongoose.connect('mongodb://localhost/planet_server', {
useMongoClient: true,
});
promise.then(function(db){
console.log('DATABASE CONNECTED!!');
}).catch(function(err){
console.log('CONNECTION ERROR', err);
});
var Schema = mongoose.Schema;
var planetSchema = new Schema({
name: String,
position: String,
moons: String,
diameterInKm: String,
daysInYear: String,
temperature: String
})
var Planet = mongoose.model('Planet', planetSchema);
Planet.collection.drop();
//*****RAW DATA*****
var firstEntry = new Planet({name: "Mercury",
position: "Mercury is the first planet in the solar system.",
moons: "Mercury has no moons",
diameterInKm: "Mercury is 5175km in diameter",
daysInYear: "A year on Mercury is a mere 88 days long",
temperature: "The surface temperature of Mercury is a scorching 427C!"
});
firstEntry.save(function (err) {
if (err) {
return (err);
}
});
var secondEntry = new Planet({name: "Venus",
position: "Venus is the second planet in the solar system.",
moons: "Venus has no moons",
diameterInKm: "Venus is 12,715km in diameter",
daysInYear: "A year on Venus is 225 days long",
temperature: "The surface temperature of Venus is a scorching 468C, hot enough to melt lead!"
});
secondEntry.save(function (err) {
if (err) {
return (err);
}
});
var thirdEntry = new Planet({name: "Earth",
position: "Earth is the third planet in the solar system.",
moons: "Earth has two moons. No, seriously. I saw it on QI.",
diameterInKm: "Earth is 12,742km in diameter",
daysInYear: "A year on Earth is 365.25 days long. That extra 0.25 is why we have leap years",
temperature: "The surface temperature of Earth...well, depends where you live, I guess."
});
thirdEntry.save(function (err) {
if (err) {
return (err);
}
});
var fourthEntry = new Planet({name: "Mars",
position: "Mars is the fourth planet in the solar system.",
moons: "Mars has two moons, Phobos and Deimos",
diameterInKm: "Mars is 6,779km in diameter",
daysInYear: "A year on Mars is 687 days long.",
temperature: "The surface temperature of Mars is a bracing -55C"
});
fourthEntry.save(function (err) {
if (err) {
return (err);
}
});
var fifthEntry = new Planet({name: "Jupiter",
position: "Jupiter is the fifth planet in the solar system.",
moons: "Jupiter has 67 moons!",
diameterInKm: "Jupiter is 139,822km in diameter",
daysInYear: "A year on Jupiter is 4380 days long. If I lived on Jupiter, I wouldn't even be 3 years old.",
temperature: "The surface temperature of Jupiter is -145C."
});
fifthEntry.save(function (err) {
if (err) {
return (err);
}
});
var sixthEntry = new Planet({name: "Saturn",
position: "Saturn is the sixth planet in the solar system.",
moons: "Saturn has 62 moons, 5 less than Jupiter, and is very bitter about it",
diameterInKm: "Saturn is 116,464km in diameter",
daysInYear: "A year on Saturn is 10,759 days long.",
temperature: "The surface temperature of Saturn is -168C."
});
sixthEntry.save(function (err) {
if (err) {
return (err);
}
});
var seventhEntry = new Planet({name: "Uranus",
position: "Uranus is the seventh planet in the solar system.",
moons: "Uranus has 5 moons",
diameterInKm: "Uranus is a relatively svelte 50,724km in diameter",
daysInYear: "A Year on Uranus is 30,660 days long.",
temperature: "The surface temperature of Uranus is -216C. That's colder than liquid nitrogen."
});
seventhEntry.save(function (err) {
if (err) {
return (err);
}
});
//*****END OF RAW DATA*****
app.get('/planet', function(req, res){
console.log(1);
Planet.find({}).exec(function(err, planet){
console.log(2);
if(err) {
return res.status(500).send(err);
}
return res.json(planet);
});
});
app.post('/planet', function(req, res){
var newPlanet = new Planet(req.body);
newPlanet.save(function(err, planet) {
if(err) {
return res.status(500).send(err);
}
return res.status(201).json(planet);
});
});
app.listen(8000, function(){
console.log('Listening');
});
在我最近的尝试中，我试图为海王星添加数据。它似乎有效，因为，正如我所说，当我在POST请求后在Postman上发出GET请求时，我可以看到海王星数据以及所有其他行星的数据。但是，我注意到JavaScript中的一个小错字。我纠正了它并保存了JavaScript文件，当我发出下一个GET请求时，Neptune数据消失了。我很困惑，所以你能给予的任何帮助都会感激不尽。
答案 0 :(得分：0)
这是因为当你重新加载你的js文件时，你正在运行这行
var Planet = mongoose.model('Planet', planetSchema);
Planet.collection.drop();
然后再次添加初始数据。因此，您发布的数据将丢失。
如果您在对文件进行更改时使用nodemon或其他东西自动刷新服务器，则不确定您是如何托管节点文件的，但这是导致数据丢失的原因，因为它是重新运行该drop命令。