Meteor-files: link() with meteor useTracker()

Created on 26 Mar 2020 · 3Comments · Source: veliovgroup/Meteor-Files

I'm having an issue when using link() on a findOne() or even find() while inside useTracker()

here is my code that produces an error:
const unitImageURL = useTracker(() => {
let image = Images.findOne({
_id: unit.images[0]
}).link()
Version of Meteor you're experiencing this issue 1.10.1
Where this issue appears? OS (Linux)? Browser chrome
Is it Client or Server issue? I do not really know
Client logs :
Uncaught TypeError: Cannot read property 'link' of undefined
at Object.reactiveFn (UnitListItem.jsx:21)
at useTracker.js:49
at tracked (useTracker.js:79)
at useTracker.js:129
at Computation._compute (tracker.js:308)
at new Computation (tracker.js:206)
at Object.Tracker.autorun (tracker.js:576)
at useTracker.js:128
at Object.Tracker.nonreactive (tracker.js:603)
at useTracker.js:127

question

Source

msgfxeg

All 3 comments

Hello @msgfxeg ,

For .findOne() method this is expected behaviour, you got to check if .findOne() has results. Feel free to open new (or more preferably PR) ticket to update FileCursor documentation and .find() method documentation. .findOne() method is meant to work similarly to default Mongo's .findOne() method, as it meant to return null when record is not found.

For .find() there is no .link() method as it returns FilesCursor.

dr-dimitru on 26 Mar 2020

Hello @dr-dimitru,
Thanks for your reply it helped me a lot.
As I am using react with meteor. the problem was that react component updates twice, the first time before the mongo query succeeded! so I have to write it as follows:

useTracker(() => {
if (
Images.findOne({
_id: unit.images[0]
}) !== undefined
) {
return Images.findOne({
_id: unit.images[0]
}).link();
}
});
P.S: a bit of redundant code but it does not heart :)