Vuejs2 将表单数据添加到后端时出现CORS问题

初学者在这里使用vue和express。我一直在尝试遵循某个教程，其中他们向数据库中添加了一个简单的表单数据，但出于某种原因，我的错误是：

CORS策略已阻止从源站访问XMLHttpRequest:对飞行前请求的响应未通过访问控制检查：它没有HTTP ok状态

以下是我在后端制作的内容：

app.use('/create',(req,res,next)=>{
    res.set({
        "Access-Control-Allow-Origin":"http://localhost:8080",
        "Access-Control-Allow-Headers":"Content-Type",
    })
    var mysql = require('mysql')
    var connection = mysql.createConnection(config)
    // SET ?
    // `FirstName`=?, `LastName`=?, `Email`=?, `ContactNumber`=?
    // [req.body.FirstName,req.body.LastName,req.body.Email,req.body.ContactNumber]
    var sql = "INSERT INTO `guest` SET `FirstName`=?, `LastName`=?, `Email`=?, `ContactNumber`=?"
    connection.query(sql,[req.body.FirstName,req.body.LastName,req.body.Email,req.body.ContactNumber],(err,results,fields)=>{
        connection.end()
        if(err){
            next(err)
        }else{
            res.json([true,results]) //.insertId
        }
    })
})

在前端：

<b-form v-model="contactForm" @submit="check();addGuest();" @reset="onReset" v-if="show"> 
                          <b-form-group
                            id="input-group-1"
                            label="Email address:"
                            label-for="input-1"
                            description="Give us an email to give a receipt to"
                          >
                            <b-form-input
                              id="input-1"
                              v-model="contactForm.Email"
                              type="email"
                              required
                              placeholder="Enter email"
                            ></b-form-input>
                          </b-form-group>

                          <b-form-group id="input-group-2" label="Your Name:" label-for="input-2">
                            <b-form-input
                              id="input-2"
                              v-model="contactForm.FirstName"
                              required
                              placeholder="Enter first name"
                            ></b-form-input>
                            <b-form-input
                              id="input-3"
                              v-model='contactForm.LastName'
                              required
                              placeholder="Enter last name"
                            ></b-form-input>
                          </b-form-group>

                        <b-form-group
                            id="input-group-3"
                            label="Contact Number"
                            label-for="input-3"
                            description="Give us a contact number to give a receipt to"
                          >
                            <b-form-input
                              id="input-4"
                              v-model='contactForm.ContactNumber'
                              type="tel"
                              required
                              placeholder="Enter Contact Number"
                            ></b-form-input>
                          </b-form-group>



                          <b-button type="submit" variant="primary">Submit</b-button>
                          <b-button type="reset" variant="danger">Reset</b-button>
                        </b-form>

---

我是不是错过了什么大事？我只是修改了我在教程中看到的内容。

在Express中激活Access Control Allow Origin并不是那么简单，但也不难：

app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "YOUR-DOMAIN.TLD"); // update to match the domain you will make the request from
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
  next();
});

app.get('/', function(req, res, next) {
  // Handle the get for this route
});

app.post('/', function(req, res, next) {
 // Handle the post for this route
});

资料来源：

---

您必须设置res.header并将其传递给Express才能使用该设置。

哦，我想这比我在教程中使用的效果更好。谢谢我希望它能满足您的需要：

app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "YOUR-DOMAIN.TLD"); // update to match the domain you will make the request from
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
  next();
});

app.get('/', function(req, res, next) {
  // Handle the get for this route
});

app.post('/', function(req, res, next) {
 // Handle the post for this route
});