Promise 保持挂起状态，“then”或“catch”未触发。 ReactJS

Question

I'm catching up to learn React. If you have any tips on this code, please share, it is very important to me:).

Why this promise doesn't work?

In console show status pending.

The promise:

_server.get(`/select`, (req, res) => {   
        return DefaultSQL.select(table).then((result) => {           
            return result
        }).catch((err) => {
            console.log(err)
        });      
})

Where I call the promise:

export const getData = (url) => {
  const response =  Server.get(url)       status
    return response.then((result) => {    // <- Not firing  
      return result 
  }).catch((err) => { // <- Not firing too
    console.log(err);
  })    
}

What the promise call:

class DefaultSQL {
  select(table) {
    const sql = `SELECT * FROM ${table}`;
    return Db.conn.query(sql).then((result) => 
      result
    ).catch((err) => {  
      console.log(err) 
    });
  }
...

EDIT:

When I change the "return result" to "return res.json(result)" the promise does not keep pending, but where I call the promise gets a error saying that "response" is not a function

Answer 1

You should rethrow the error/throw a new error to catch error again .

It's an example:

 Promise.reject("throwed on demo 1").catch((e) => { console.log("Catched", e) }).catch((e) => { // unreached block console.log("Can NOT recatch", e) }) Promise.reject("throwed on demo 2").catch((e) => { console.log("Catched", e) throw e }).catch((e) => { console.log("Recatched", e) })

UPDATE: Another issue, you need to send a response even error/success. Otherwise, the request will not respond, the client will be pending forever.

_server.get(`/select`, (req, res) => {   
        return DefaultSQL.select(table).then((result) => {           
            res.send(result)
            //return result
        }).catch((err) => {
            res.status(500).send(err)
            console.log(err)
        });      
})