attach helpers to rawCollection? about meteor-collection-helpers HOT 7 CLOSED

Thanks @niklasdahlheimer! all you need to do is apply the helpers to the object, see this example: https://github.com/dburles/meteor-collection-helpers#applying-the-transformation-function

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Thanks @dburles, that works for single objects pretty well but I can't make it work with a Meteor collection as param in a function.

function searchWithRegEx(meteorCollection, searchString) {
    return meteorCollection.rawCollection()
        .find({"someKey": new RegExp(searchString, "gi")})
        .toArray()
        .then(array => array.map(result => meteorCollection._transform(result)));
};

Any idea on this? Thanks!

from meteor-collection-helpers.

That should result in the methods being applied to each object. However, looking at the use of an arrow function it's likely that calling methods that refer to this might not be correctly referring to the object itself.

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I tried

1. replace the arrow functions with ordinary functions

function searchWithRegEx(meteorCollection, searchString) {
    return meteorCollection.rawCollection()
        .find({"someKey": new RegExp(searchString, "gi")})
        .toArray()
        .then(function (array) {
            array.map(function (result) {
                meteorCollection._transform(result)
            })
        });
};

2. using call() to pass the collection explicitly as the this object

...
meteorCollection._transform.call(meteorCollection, result);
...

None of that helped.
When I log the passed meteorCollection by calling
console.log(meteorCollection)
it prints out:

SomeCollection {
...
_helpers: [Function: Document]
...
}

So it looks like the helper functions are attached to it. Probably I still have a false understanding of the this keyword, I'm pretty confused why it's not returning the transformed result correctly.

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I made some progress on this.

It turns out that meteorCollection._transform(result) indeed adds the correct helpers as prototypes!
The problem is, that my function lives inside a Meteor method (which of course runs serverside) and the results are passed via an async callback-function to the client and that is where the helpers disappear

• calling Object.getPrototypeOf(myObj) in the Meteor method -> helpers are available
• calling Object.getPrototypeOf(myObj) in the callback function inside the Meteor.call -> helpers are gone, only default prototypes are shown (constructor, hasOwnProperty,..)

I searched around in the Meteor API reference and Meteor guide but could not find anything related to this issue. Could it be that these helper-methods are not serializable and are thrown away when Meteor passes the results to the client or that Meteor somehow reduces the object to only contain properties?

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@niklasdahlheimer Ah I see, yeah that makes sense. That's right, it's just a serialised object being sent across. In that case just apply the helpers to the document returned from the method on the client.

from meteor-collection-helpers.

Yes. I will have to do the transformation at a lot of places because the serverside function was meant to be "generic", but there seems to be no other work around.
Because it's likely anothers will stumble across this problem, I would suggest a little note/hint in the Git Readme, but it's yours to decide if it's common knowledge that prototypes are not serializable and couldn't be passed over the wire :)

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