How-to integrate with an existing store ?

cozy-client uses redux internally to centralize the statuses of the various fetches and replications triggered by the library, and to store locally the data in a normalized way. If you already have a redux store in your app, you can configure cozy-client to use this existing store:

import CozyClient from 'cozy-client'
import { combineReducers, createStore, applyMiddleware } from 'redux'
import myReducers from './myapp/reducers'
import myMiddleware from './myapp/middleware'

const client = new CozyClient({

const store = createStore(
  combineReducers({ ...myReducers, cozy: client.reducer() }),

  <CozyProvider client={client} store={store}>
    <MyApp />

How to connect to the documents store declaratively ?

Sometimes, HOCs are better suited than render-prop components, especially if you have multiple data-sources and you do not want to have multiple indent levelves. We provide a higher-order component called connect. Basic example of usage:

import React from 'react'
import { connect } from 'cozy-client'

const query = client => client.find('io.cozy.todos').where({ checked: false })

const TodoList = ({ data, fetchStatus }) =>
  fetchStatus !== 'loaded'
    ? <h1>Loading...</h1>
    : <ul>{ => <li>{todo.label}</li>)}</ul>

export default connect(query)(TodoList)

When we use connect to bind a query to a component, three things happen: - The query passed as an argument will be executed when the component mounts, resulting in the loading of data from the client-side store, or the server if the data is not in the store ; - Our component subscribes to the store, so that it is updated if the data changes ; - props are injected into the component: if we were to declare propTypes they would look like this:

TodoList.propTypes = {
  fetchStatus: PropTypes.string.isRequired,
  data: PropTypes.array

How to provide a mutation to a component ?

withMutation provides only a simple function to the wrapper component, in a prop called mutate:

import { withMutation } from 'cozy-client'

const AddTodo = ({ mutate: createTodo }) => {
  let input

  return (
    <form onSubmit={e => {
      input.value = ''
      <input ref={node => { input = node }} />
      <button type="submit">Add Todo</button>

export default withMutation(
  label => client => client.create('io.cozy.todos', { label })

How to specify a schema ?

Each doctypes accessed via cozy-client needs to have a schema declared. It is useful for

Here is a sample of a schema used in the Banks application.

const { HasMany } = require('cozy-client')

class HasManyBills extends HasMany {

class HasManyReimbursements extends HasMany {

const schema = {
  transactions: {
    doctype: '',
    attributes: {},
    relationships: {
      account: {
        type: 'belongs-to-in-place',
        doctype: ''
      bills: {
        type: HasManyBills,
        doctype: 'io.cozy.bills'
      reimbursements: {
        type: HasManyReimbursements,
        doctype: 'io.cozy.bills'

const client = new CozyClient({

Here we can see that banking transactions are linked to

Custom relationships are useful if the relationship data is not stored in a built-in way.

Validation is not yet implemented in cozy-client.