updux/docs/recipes.md

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2022-08-30 20:10:38 +00:00
# Recipes
## Mapping a mutation to all values of a state
Say you have a `todos` state that is an array of `todo` sub-states, with some
actions that should percolate to all todos, and some that should only
percolate to one. One way to model this is via updux's splat subduxes
(backed by `updeep`'s own '*'-key behavior).
```
const done = () => (state) => ({...state, done: true});
const todo = new Updux({
initial: { id: 0, done: false },
actions: {
done: null,
doneAll: null,
},
mutations: {
done,
doneAll: done,
},
});
const todos = new Updux({
initial: [],
subduxes: { '*': todo },
actions: { addTodo: null },
mutations: {
addTodo: text => state => [ ...state, { text } ]
}
});
todos.setMutation(
todo.actions.done,
(text,action) => u.map(u.if(u.is('text',text), todo.upreducer(action))),
true // prevents the subduxes mutations to run automatically
);
```
## Usage with Immer
While Updux was created with Updeep in mind, it also plays very
well with [Immer](https://immerjs.github.io/immer/docs/introduction).
For example, taking this basic updux:
```
import Updux from 'updux';
const updux = new Updux({
initial: { counter: 0 },
mutations: {
add: (inc=1) => state => ({ counter: state.counter + inc })
}
});
```
Converting it to Immer would look like:
```
import Updux from 'updux';
import { produce } from 'immer';
const updux = new Updux({
initial: { counter: 0 },
mutations: {
add: (inc=1) => produce( draft => draft.counter += inc ) }
}
});
```
But since typing `produce` over and over is no fun, `groomMutations`
can be used to wrap all mutations with it:
```
import Updux from 'updux';
import { produce } from 'immer';
const updux = new Updux({
initial: { counter: 0 },
groomMutations: mutation => (...args) => produce( mutation(...args) ),
mutations: {
add: (inc=1) => draft => draft.counter += inc
}
});
```