Realm.Results.map is not a function?

[pedrosimao]

Goals

I did query a Realm collection

Expected Results

I expect to be able to execute .map() or .forEach() methods on Realm results.

Actual Results

When I console.log() the realm results I see well that the type of the object is a result.
But when I do try to execute .map() method on it I get the following error:
TypeError: schedules.map is not a function

Code Sample

let selected = realm.objects('SchemaName');
selected.map(selection => .... )

Version of Realm and Tooling

• Realm JS SDK Version: ?
  2.15.3
• Node or React Native: ?
  RN: 0.56.0
• Client OS & Version: ?
  Mac OSx

[pedrosimao]

I just found a workaround this issue.

Instead of using map() function, I just needed to find the selected.length, and use it inside a for loop, like this:

for (let i = 0; i < selected.length; i++){...
selected[i] ...}

An implementation of map or forEach methods would be a great plus.

[pedrosimao]

Given that I have found a solution I will close the issue.
But developers should really think about include some modern Javascript methods on Realm.objects and Realm.results.
RealmJS should follow the tendencies of modern javascript syntax... Also this kind of operations could be better documented.

[nirinchev]

@kneth is this a RN bug? I am fairly certain we've used .map with node apps.

[pedrosimao]

Well, it could be. I have noticed that running the same code on Simulator + Debugger and on a real iOs device sometimes give me different results. Anyway on RN it didn't work for me in any of the cases. Maybe this issue is something to be looked on. Should I reopen it?

[nirinchev]

Yes, let's check it out.

[pedrosimao]

Quick update, it seems on React Native it is possible to use .map or .forEach methods like this:
Object.keys(object).forEach((key) => ... do something with key )
Chaining the method directly on the object like object.forEach(key => ...) will cause the error described.
I am not sure it is supposed to be like that. If it is the case it would be great to see that in the docs.

[kneth]

I think it is related to https://medium.com/@jordan_mohi/cant-find-variable-symbol-in-react-native-782489d86bd7

[Udbhav12]

I am facing this exact issue in RN 0.58.6 and above,It was working fine in RN 0.57.8 and below

[febeling]

Confirming this problem for react-native@0.55.3

[febeling]

Also see this with Realm.List, not just Realm.Results.

[Rob117]

Just to be clear, this is still an issue. When you search for realm node foreach, this comes up on the first page.

If you check all the methods that should be available on the object using (taken from SO)

    const getMethods = obj => {
      let properties = new Set();
      let currentObj = obj;
      do {
        Object.getOwnPropertyNames(currentObj).map(item => properties.add(item));
      } while ((currentObj = Object.getPrototypeOf(currentObj)));
      return [...properties.keys()].filter(item => typeof obj[item] === 'function');
    };

  console.log(getMethods(resultsObject));

This will tell you that forEach should be on that object, but trying to actually call it returns not a function

[davidleee]

We've spotted the same error on our Electron app.

I know Realm does not currently support Electron, but maybe this is not an RN-only issue?

[kneth]

It can be related to #1096.

[kneth]

We believe this is fixed by v12. Please reopen or create a new issue if it is still a problem.