React-data-dam NPM

react-data-dam

Holds back your data until you're ready to see the updates. Useful for implementing a Twitter style "See n new Tweets" button.

Initial data passed to DataDam will be passed onto it's children, but changes to that data are held back until the children signal that they want to receive it. Children are passed a diff object which describes the difference between the data they currently have and what is being held back so they know what they're missing.

Install

npm install react-data-dam

Usage

import React from 'react'
import { DataDam } from 'react-data-dam'

export default ({ items }) => (
  <DataDam data={items}>
    {(data, diff, release) => (
      <div>
        <ul>
          {data.map((d) => <li>{d._id}</li>)}
        </ul>
        {diff.total.changes ? (
          <button onClick={release}>Load {diff.total.changes} updates</button>
        ) : null}
      </div>
    )}
  </DataDam>
)

API

`<DataDam />`

`data`

Type: PropTypes.arrayOf(PropTypes.object).isRequired

The data you want to build a dam against. Only the initial value will be passed through to child components until release is called.

The flowing prop can be used to allow data through from initial mount to a time that you're ready to enforce the dam.

Objects in the array should have an _id property to determine updates. This can be changed using the idProp prop.

`children`

Type: PropTypes.func.isRequired

A function that renders the children. It is passed 3 parameters:

data - the cached data since the last release or initial mount
diff - the difference between the passed data and the data that is being held back
release - a function to call that will release any data that is held back

The diff object looks like this:

{
  added: [], // items that were added to data
  removed: [], // items that were removed from data
  updated: [],  // items that remained in data but were altered in some way
  moved: [], // items that changed index
  total: {
    changes: 0, // added + removed + updated
    added: 0,
    removed: 0,
    updated: 0,
    moved: 0
  }
}

`flowing`

Type: PropTypes.bool, default: false

Allow data to flow freely through the dam without needing to call release.

`idProp`

Type: PropTypes.string, default: _id

Changes the property that is considered to be the ID of the data items.

`autoRelease`

Type: PropTypes.func

Called each time the held back data changes. When this function returns true the held back data will be released. It is passed 4 parameters:

data - the cached data since the last release or initial mount
diff - the difference between the passed data and the data that is being held back
nextData - the data that is being held back
incrementalDifference - a function you can call to calculate the incremental diff, which is the difference between the previous nextData and the new nextData