How to call a function inside bluebirdjs promise

I am trying to get a promise function with bluebirdjs. but all attempts falling my way because maybe I don't know what I am doing...?

I want to get files locations, then download the files one after the other then push to an array.

import * as Promise from 'bluebird';
fileFunction(files)
Promise.map(files, function(file)
// Promise.map awaits for returned promises as well.
//Promise.delay(1000);
return this.getLocation(file);
,
).then((file) =>
console.log('done')
);



getLocation(file){
if(file)
return this._storage.ref(file).getDownloadURL().subscribe(url =>
this.img_array.push(url)
);



When I call the return this.getLocation(file)... I get the following error
bluebird.js:1545 Unhandled rejection TypeError: Cannot read property 'getLocation' of undefined ....bluebird.js

error
bluebird.js:1545 Unhandled rejection TypeError: Cannot read property 'getLocation' of undefined ....bluebird.js

Edit part of the code am using now!

fileFunction(files)
return Promise.map(files, file =>
return this.getDownloadUrl(file);
).then(locations =>
// add these locations onto this.img_array
this.img_array.push(...locations);
console.log('done');
return locations;
);



getFiles(e): Promise<any>
this.outPutFiles = e;

this.fileFunction(this.outPutFiles).then(locations =>
locations.map((arr) => arr.subscribe((files) => this.downloadUrls.push(files)));
).catch(err =>
console.log(err);
);



getDownloadUrl(file)
if(file)
return this._storage.ref(file).getDownloadURL();
else
return Promise.reject(new Error('No file passed to getLocation'));




Promise.map(files, (file) =>

)

getLocation

this

return getLocation(file);

getLocation

fileFunction

this.getLocation

getLocation()

1 Answer
1

this.getLocation(file) does not work because you've lost the value of this because you're inside a Promise.map() callback. Remember, that every normal function call in Javascript changes the value of this unless you specifically control the value of this.

this.getLocation(file)

this

Promise.map()

this

this

You can fix that part of the issue with a simple arrow function for your callback like this:

fileFunction(files)
return Promise.map(files, file =>
return this.getLocation(file);
).then(locations =>
// add these locations onto this.img_array
this.img_array.push(...locations);
console.log('done');
return locations;
);



This assumes that this.getLocation(file) returns a promise that resolves to the location value. Are you sure it does that? It looks like there may be more to your problem than just that first error you ran into.

this.getLocation(file)

And, after a side conversation, you also need to fix getLocation() to return a promise that resolves to the desired URL. Looking in the firebase Javascript doc, it appears that getDownloadURL() already returns a promise that resolves to the desired URL. So, you can just return that promise and let Promise.map() manage the results for you.

getLocation()

getDownloadURL()

Promise.map()

getLocation(file)
if(file)
return this._storage.ref(file).getDownloadURL();
else
return Promise.reject(new Error("No file passed to getLocation"));




And, then you would use it all like this:

obj.fileFunction(fileArray).then(locations =>
console.log(locations);
).catch(err =>
console.log(err);
);


this.getLocation(file)

this.img_array

files

this.files=[0: "xngb", 1: "bdje"]

this.img_array=[0: "...bdje", 1: "...xngb"]

getLocation(file)

getLocation()

getLocation()

Promise.map()

this.img_array.push(url)

Promise.map()

getLocation(file) return this._storage.ref(file).getDownloadURL().subscribe(url => // console.log(url) this.img_array.push(url) );

this.img_array

files

getLocation()

this._storage.ref(file).getDownloadURL().subscribe(...)

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