Best practise of handling normalised Entities?

[ms88privat]

In my first App with Redux, I am trying to keep my collections normalised as recommended. This way you only have to change the Entities in one place. (this feels right to me)

At first i successfully normalised my Array of data to an Array-like-Object of Entities with the id's as key's

Then i wanted to list the entities in a View, so i had to parse it back to an Array. Also if i want to filter my Entities, i need the real Array. Is this really the right approach?

Example with re-select:

    // As "id" for my images i use "uri"

    imageEntities = {
     uri1: {image...},
     uri2: {image...},
    ....
    }

    // Selectors:
    const imagesSelector = state => state.images;

    // parse the Array-like-Object to an Array
    const imagesArySelector = createSelector(
      [imagesSelector],
          images => {
            let ary = [];
            for (var key in images) {
              if (images.hasOwnProperty(key)) {
                ary.push(images[key]);
              }
             }
            return ary;
          }
     );

    // filter the Array to get only the new images
    export const newImagesSelector = createSelector(
      [imagesArySelector],
        images => images.filter(image => image.isNew)
     );

Is this really the right approach? (it is working fine, from what i see until now)

[itsmepetrov]

I think it can be done more elegantly.
How I do it:

import { createSelector } from 'reselect';

const providersSelector = state => state.entities.providers;
const subscribersSelector = state => state.entities.subscribers;

export const providersArraySelector = createSelector(
    [providersSelector],
    providers => Object.keys(providers).map(id => providers[id])
);

export const subscribersArraySelector = createSelector(
    [subscribersSelector],
    subscribers => Object.keys(subscribers).map(id => subscribers[id])
);

[ms88privat]

@itsmepetrov looks a'lot better... thx.

So in principle I am on the right track. Anybody else?

[gaearon]

Then i wanted to list the entities in a View, so i had to parse it back to an Array.

You can keep an array of IDs when arrays are more convenient to work with. You'll need to do this for things like pagination. The real-world example in examples folder does that.