I've tied myself up in knots trying to return from a function which uses chained asynchronous node-fetches. Please help since I'm not familiar with promises and the like
In the function MessgSums() I am initially fetching a list of conversations which works fine.
convlst = fetch(url+'/conversations', settings)
I then use the result of this fetch to perform a loop of fetches for all conversations
for(i=0;i<dat.length;++i){
convDetails = fetch(url + '/conversations/'+dat[i].id+'/messages')
.then(res => res.json())
.then((msgDetails)=>{
This too works fine.
I next populate an object with the data returned by 2 fetch calls as shown below and then push the constructed object into an array. This too works fine.
convDetails = fetch(url + '/conversations/'+dat[i].id+'/messages')
.then(res => res.json())
.then((msgDetails)=>{
var msgobj = {
id:msgDetails[0].conversation_id,
latest_message : {
body:msgDetails[0].body,
from_user:{},
created_at:msgDetails[0].created_at
}
}
fetch(url + '/users/'+msgDetails[0].from_user_id)
.then(res => res.json())
.then((user) => {
msgobj.latest_message.from_user = {
id:user.username,
avatar_url : user.avatar_url
}
//push to array
allmsgs.push(msgobj);
})
});
};
return allmsgs;
});
At the very end of the outer then() I return the array allmgs.
I next call the function but get an undefined error most probably because the asynchronous call has not completed.
var msgarr = MessgSumms(); //how do i call MessgSums and capture the returned array allmsgs
console.log(msgarr); //gives undefined
How do I capture the populated array once it has been fully constructed and returned by MessgSums()??
Here is what I've coded
const express = require('express');
const fetch = require('node-fetch');
const app = express();
app.use(express.json());
app.use(express.urlencoded({extended:true}));
const portnum = process.env.PORT || 3000;
app.listen(portnum, () => {
console.log("Server is listening on port "+portnum);
});
//--------------------------- Urls for App Center REST functions-----------------------//
var url = 'https://someurl/api';
let settings = {method:"get"};
var convDetails;
var allmsgs = [];
var convlst;
//----------------------------------------------------------------------------------//
function MessgSumms() {
convlst = fetch(url+'/conversations', settings)
.then(res => res.json())
.then((conversationsList) => {
return conversationsList;
});
convlst.then(dat => {
for(i=0;i<dat.length;++i){
convDetails = fetch(url + '/conversations/'+dat[i].id+'/messages')
.then(res => res.json())
.then((msgDetails)=>{
//console.log("CID : " +msgDetails[0].conversation_id);
//console.log("MBody : " +msgDetails[0].body);
//console.log("CDate : " +msgDetails[0].created_at);
var msgobj = {
id:msgDetails[0].conversation_id,
latest_message : {
body:msgDetails[0].body,
from_user:{},
created_at:msgDetails[0].created_at
}
}
//console.log("From : " +msgDetails[0].from_user_id);
fetch(url + '/users/'+msgDetails[0].from_user_id)
.then(res => res.json())
.then((user) => {
//console.log('UName : '+user.username);
//console.log('UAvatar : '+user.avatar_url);
//console.log("--------------------------------------------------");
msgobj.latest_message.from_user = {
id:user.username,
avatar_url : user.avatar_url
}
console.log("Object Starts")
console.log("------------------------------------")
console.log("ID :" + msgobj.id);
console.log("Latest Msg Body :" + msgobj.latest_message.body);
console.log("From User :" + msgobj.latest_message.from_user.id);
console.log("User Avatar :" + msgobj.latest_message.from_user.avatar_url);
console.log("Created at :" + msgobj.latest_message.created_at);
//push to array
allmsgs.push(msgobj);
})
});
};
return allmsgs;
});
}
var msgarr = MessgSumms(); //how do i call MessgSums and capture the returned array allmsgs
console.log(msgarr); //gives undefined
