src/sagas/README.md
# Reducers
This is a quick reference for reducer methods. Please also see [constants](../CONSTANTS.md) for default reducer state.
## combine(defaultState, reducers)
Returns reducer collection that responds to actions specified by object. It is used to avoid writing unnecessary switch statements.
This example will respond to USERS_SET, USERS_FETCH_START, USERS_CLEAR.
```javascript
import { combine } from 'react-saga-rest';
const USERS_CLEAR = 'USERS_CLEAR';
const USERS_FETCH_START = 'USERS_FETCH_START';
const USERS_SET = 'USERS_SET';
const initialState = {
users: [],
loading: false,
};
const reducer = combine(initialState, {
[USERS_SET]: (state, action) => ({
users: action.users,
loading: false,
}),
[USERS_FETCH_START]: state => ({ loading: true }),
[USERS_CLEAR]: state => ({ ...initialState }),
});
```
## fetchError
Dummy reducer method that is used as a handler of fetch saga error responses.
```javascript
import { combine, fetchError } from 'react-saga-rest';
const reducer = combine(initialState, {
[USERS_FETCH_FAIL]: fetchError,
});
// Example run
reducer(undefined, {
type: USERS_FETCH_FAIL,
missing: true,
valid: true,
error: new Error(),
});
// The result
{
failed: true,
loading: false,
missing: true,
valid: false,
error: new Error(),
};
```
## fetchStart
Dummy reducer method that is used as a handler of fetch start action.
```javascript
import { combine, fetchStart } from 'react-saga-rest';
const reducer = combine(initialState, {
[USERS_FETCH_START]: fetchStart,
})
// Example run
reducer(undefined, { type: USERS_FETCH_START });
// The result
{
failed: false,
loading: true,
missing: false,
};
```
## fetchSuccess
Dummy reducer method that is used as a handler of fetch saga success responses.
```javascript
import { combine, fetchSuccess } from 'react-saga-rest';
const reducer = combine(initialState, {
[USERS_FETCH_SUCCESS]: fetchSuccess,
});
// Example run
reducer(undefined, {
type: USERS_FETCH_SUCCESS,
data: [
{ name: 'Robert Horse' },
{ name: 'Hobert Norse' },
]
});
// The result
{
failed: false,
loading: false,
missing: false,
valid: true,
data: [
{ name: 'Robert Horse' },
{ name: 'Hobert Norse' },
],
};
```
## invalidate
Dummy reducer method that is used to invalidate the reducer state.
```javascript
import { combine, invalidate } from 'react-saga-rest';
const reducer = combine(initialState, {
[USERS_INVALIDATE]: invalidate,
});
// Example run
reducer(undefined, { type: USERS_INVALIDATE });
// The result
{
loading: false,
valid: false,
}
```
## invalidateOnCollectionChange(identAttr, actionIdentAttr = null)
Smart reducer method that is used to invalidate the reducer state and reset page on the same time when a parent resource ID changes and the collection state is no longer valid. For example, when you are displaying list of users group on user detail page and display another user.
```javascript
import { combine, invalidateOnCollectionChange } from 'react-saga-rest';
const reducer = combine(initialState, {
[USER_CHANGE]: invalidateOnCollectionChange('userId'),
});
// Example run
reducer({ userId: 939 }, { type: USER_CHANGE, userId: 10 });
// The result
{
userId: 10,
page: 0,
valid: false,
}
```
## invalidateOnResourceChange(identAttr, actionIdentAttr = null)
Smart reducer method that is used to invalidate the reducer state when a parent resource ID changes and the resource state is no longer valid. For example, when you are displaying user detail page and user ID gets changed.
```javascript
import { combine, invalidateOnResourceChange } from 'react-saga-rest';
const reducer = combine(initialState, {
[USER_CHANGE]: invalidateOnResourceChange('userId'),
});
// Example run
reducer({ userId: 939 }, { type: USER_CHANGE, userId: 10 });
// The result
{
userId: 10,
valid: false,
}
```
## pageReset
Dummy reducer method used to reset its page to zero.
```javascript
import { combine, pageReset } from 'react-saga-rest';
const reducer = combine(initialState, {
[USER_PAGE_RESET]: pageReset,
});
// Example run
reducer({ page: 1000 }, { type: USER_PAGE_RESET });
// The result
{
page: 0,
valid: false,
}
```
## pageSet
Dummy reducer method used to change its page.
```javascript
import { combine, pageSet } from 'react-saga-rest';
const reducer = combine(initialState, {
[USER_PAGE_CHANGE]: pageSet,
});
// Example run
reducer({ page: 1000 }, { type: USER_PAGE_CHANGE, page: 20 });
// The result
{
page: 20,
valid: false,
}
```
## toggle(property)
Dummy reducer method used to toggle one property value on and off.
```javascript
import { combine, toggle } from 'react-saga-rest';
const reducer = combine(initialState, {
[USER_TOGGLE_DELETE_MODAL]: toggle('showDeleteModal'),
});
// Example run
reducer({ showDeleteModal: true }, { type: USER_TOGGLE_DELETE_MODAL });
// The result
{
showDeleteModal: false,
}
```
## turnOff(property)
Dummy reducer method used to turn off one property.
```javascript
import { combine, turnOff } from 'react-saga-rest';
const reducer = combine(initialState, {
[USER_HIDE_DELETE_MODAL]: turnOff('showDeleteModal'),
});
// Example run
reducer({ showDeleteModal: true }, { type: USER_HIDE_DELETE_MODAL });
// The result
{
showDeleteModal: false,
}
```
## turnOn(property)
Dummy reducer method used to turn on one property.
```javascript
import { combine, turnOn } from 'react-saga-rest';
const reducer = combine(initialState, {
[USER_SHOW_DELETE_MODAL]: turnOn('showDeleteModal'),
});
// Example run
reducer({ showDeleteModal: false }, { type: USER_SHOW_DELETE_MODAL });
// The result
{
showDeleteModal: trues,
}
```