redux-jam

redux-jam is a framework for managing the complexity of multiple data sources with different fetching and storage characteristics, while using standard, flexible, and known systems, such as Redux.

Storing data fetched from a server locally is a very attractive method of improving user experience, but it comes with significant difficulties. Deciding when to invalidate a locally cached dataset, and how to combine remote and local data can be a source of immense complexity. This is especially true when building an application designed for offline capabilities.

Installation

npm install redux-jam

or

yarn add redux-jam

Add the JAM model reducer to your root reducer:

import {reducer as model} from 'redux-jam'
 
const rootReducer = combineReducers({
  model,
  ...
})
 
export default rootReducer

Defining a Schema

Before data can be manipulated a schema describing the structure of the data must be defined. There are a number of ways to do it, the two most common are to define the data manually, or import it automatically using an external package.

Manual Definition

Schemas are built using the Schema class:

import {Schema} from 'redux-jam'
 
let schema = new Schema()

To define models in a schema, use the merge method, which accepts an object argument describing a part of a schema:

schema.merge({})

merge may be called any number of times. Each subsequent call will overwrite any overlapping models.

The structure of the schema object is similar in some ways to the structure of a JSON-API object. Take for example the following definition of a movie:

{
  movie: {
    attributes: {
      name: {
        required: true        
      },
      duration: {},
      year: {}
    },
    relationships: {
      actors: {
        type: "person",
        many: true,
        relatedName: "actedIn"
      }
    }
    api: {
      list: () => {},
      detail: () => {},
      create: () => {},
      update: () => {},
      delete: () => {}
    }
  },
  person: {
    attributes: {
      name: {
        required: true
      }
    },
    api: {
      list: () => {},
      detail: () => {},
      create: () => {},
      update: () => {},
      delete: () => {}
    }
  }
}

This defines two models: movie and person. The api sections of each model are placeholders for calls to API endpoints. They should return promises, which in turn return JSON-API structured data.

Options for attributes are currently limited to required.

Options for relationships:

• type

• required

• many

• relatedName

Django + DRF

If you're using Django and DRF, your schema can be loaded into JAM automatically, which is particularly convenient.

Refer to Django-JAM

Loading Data

Fetching data from the server is achieved with a higher order comonent, withView. Views collect a set of one or more queries and provide the resultant data to a React component.

The following snippet shows a React component that loads movies whose title contains the term "Rocky", and sorts them on year:

import React from 'react'
import {withView} from 'redux-jam'
import schema from 'models'
 
const view = schema.view({
  name: 'movieList',
  queries: {
    movies: {
      type: 'movie',
      filter: F.contains('title', 'Rocky'),
      sort: 'year'
    }
  }
})
 
@withView(view)
class MoviesList extends React.Component {
  render() {
    const {moviesList} = this.props
    const {loading, queries} = moviesList
    if (!loading) {
      return (
        <ul>
          {queries.movies.map(m => <li>{m.title}</li>}
        </ul>
      )
    }
    else
      return null
  }
}

Mutating data

redux-jam provides a form like interface for mutating data.

import React from 'react'
import {withForm} from 'redux-jam'
import schema from 'models'
 
@withForm({type: 'movie'})
class MoviesList extends React.Component {
  render() {
    const {renderField} = this.props
    // TODO
  }
}

Filtering

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