CODEWITHSUNDEEP
javascriptmeteor
user3142695
user3142695

Reputation: 17372

Meteor: Prevent undefined result for findOne()

I want to get some information out of a collection - in this example the user collection; but could be anything:

var result = Users.findOne({ _id: Meteor.userId() }).profile.anything;

In some cases the information is missing. For example if the DB is empty, I would get the error Exception in template helper: TypeError: Cannot read property 'profile' of undefined.

What would be the best way to prevent this if I'm using findOne and get an undefined result?

I would do something like:

var temp = Users.findOne({ _id: Meteor.userId() });
    if (temp) 
        var result = temp.profile.anything;

But that looks not very elegant.

Upvotes: 0

Views: 50

Answers (1)

David Weldon
David Weldon

Reputation: 64342

I cover this in some detail in my post on guards. This isn't really an issue with meteor or even the find operations - its just defensive programming in JavaScript. The generally accepted practice in cases where a guard may be needed is something like:

x && x.y && x.y.z

which covers the case where one or more of x and y are undefined.

You may run into situations where a long function is predicated on the existence of some piece of data. In those situations you may want to do something like:

user = Meteor.user();
if (!user) return;
...
// rest of function which assumes user is defined

Upvotes: 1

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