A libx-esque Collection infrastructure for MobX applications. Based off of libx by jeffijoe.

"I hate regular lists, I'm always getting duplicate items" - 733T-Hck3r-man-27

"How can anyone possibly maintain a list of objects and dynamically update them in realtime?!" - Tom Cruise

Well not to fear my friends, libxd is here!

libxd maintains a collection of items, making sure we only have a single instance of an entity in memory. It even uses Mobx! That way, updates to an entity will propagate to the entire system without us having to do anything at all.

Be sure to install the latest build_runner pakcage and run flutter packages pub run build_runner build. This is used to generate the needed mobx_codegen files.

The libxd Collection allows us to easily manage a list of any model type. It can ensure each item is unique based on the model ID.

libxd uses the mobx_dart package to ensure changes to the collection items can be observed and can propagate on your app in realtime.

Each item is required to have an ID variable. By default libxd tries to access the id param on your object (aka item.id). You can specify which field is your ID by overriding the getModelId method when instantiating your Collection.

Collection<Car> cars = Collection<Car>(
    getModelId: (c) => c.vinNumber
);

Now everytime you add a new Car to your Collection it will ensure it is unique by it's VIN number.

Ok, so how do we go about updating and adding things to our Collection?

For example, lets say we have a User model:

class User {
    String id;
    String name;
    String email;
}

We can easily add items and update items in our collection by using the set or setAll methods:

Collection<User> users = Collection<User>();

final someApiRequest = await dio.get('/users');
final result = someApiRequest.data.map((json) => User.fromJson(json));

users.setAll(result);

This will add all User objects to our collection and update any duplicates.

Note: we don't need to specify getModelId since our class has an id field.

Say I have a list of objects that need to be ordered based on a specific field. Well libxd does that!

Simply specify the sortBy field when instantiating a new Collection:

Collection<Messages> messages = Collection<Messages>(
    sortBy: CollectionSort<Messages>((m) => m.dateSent.toString(), 'desc'),
);

Now, whenever the items in the collection are updated, the collection will be sorted accordingly.

"Ok, but I don't want to sort every time the collection is updated..." - anonymous user

Well not to fear, we got you covered!

Just call sort on your collection and specify the field to be sorted on.

notifications.sort((n) => n.dateCreated.toString(), 'asc');

libxd makes it super simple to remove objects from your collection.

final item = SomeItem();
collection.set(item);

collection.remove(item);

collection.removeById(item.userId);

Empties the collection and preps it to receive new items.

collection.clear()

"I'm implementing some sweet drag n' drop funcitonality, but I have to do this convoluted code to move things around in my list... pls help!" - noob coder

Not to worry, libxd has your back!

Simply call move and specify your from index and to index.

collection.move(2, 7);

Creator: jeffijoe

Github: https://github.com/jeffijoe/libx