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https://github.com/VoliJS/NestedLink

Callback-free React forms with painless validation.
https://github.com/VoliJS/NestedLink

data-binding forms javascript react react-links typescript

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Callback-free React forms with painless validation.

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README 

        
![logo](/images/value-link-logo.png)



# Painless React forms, validation, and state management



NestedLink is `useState` React Hook on steroids providing an elegant callback-free solution for complex forms with input validation and making the React state a perfect state container. It's lightweight (6.5K minified) and designed to be used with both JS and TypeScript.



The `Link` is the object representing the writable reference to the member of the component's state encapsulating the value, function to update the value, and the validation error. `Link` class has a set of methods to perform useful transformations, such as `$link.props` generating the pair of standard `{ value, onChange }` props.



`NestedLink` dramatically improves your React project's modularity and code readability.



```javascript

import { useLink } from 'valuelink'

import { MyInput } from './controls.jsx'



const coolState = { some : { name : '' } };

const MyCoolComponent = () => {

    // Digging through the object to get a link to the `coolState.some.name`

    const $name = useLink( coolState ).at( 'some' ).at( 'name' )

    

    // applying the validation rules

    $name.check( x => x.length > 0, 'Name is required' ),

         .check( x => x.length > 2, 'Name is too short' );

         .check( x => x.length < 20, 'Name is too long' );



    return (

        

    )

}



// controls.jsx

import * as React from 'react'



// Custom form field with validation taking the link to the `value`

const MyInput = ({ $value }) => (

    


        

        { $value.error || '' }

    


)

```



## Features



***IMPORTANT! Version 2.x is not entirely backwards compatible with 1.x, see the release notes at the bottom.***



- Callback-free form controls binding to the component state.

- Complete separation of the validation logic from the markup.

- Easy handling of nested objects and arrays in the component state.

- Complete support for the React Hooks API and functional components.

- Pricise TypeScript typings.



Reference implementation of 'linked' UI controls (optional `linked-controls` npm package):



- Standard tags: ``, ``, ``,

- Custom tags: ``, ``, ``

- Validator functions: `isNumber`, `isEmail`, `isRequred`.



## Tutorials



The rationale behind the design and a high-level overview of how amazing NestedLink is: [React Hooks, form validation, and complex state](https://itnext.io/react-hooks-and-two-way-data-binding-dd4210f0ed94)



The series of 5-minute tutorials (with `React.Component`):



- [The basics of ValueLink design pattern](https://medium.com/@gaperton/managing-state-and-forms-with-react-part-1-12eacb647112#.j7sqgkj88)

- [Form validation with ValueLinks](https://medium.com/@gaperton/react-forms-with-value-links-part-2-validation-9d1ba78f8e49#.nllbm4cr7)

- [Complex state with ValueLinks](https://medium.com/@gaperton/state-and-forms-in-react-part-3-handling-the-complex-state-acf369244d37#.x0fjcxljo)



### [API Reference](/valuelink/API.md)



### [Linked Controls Reference](/linked-controls/README.md)



### [Examples](https://volijs.github.io/NestedLink)([sources](/examples/))



## How to



### Use it in your project



There are no side dependencies except `react` as peer dependency. Installation:



`npm install valuelink --save-dev`



Usage with React Hooks (check out the [React Hooks starting boilerplate](/examples/babel-starter)).



```javascript

import React from 'react'

import { useLink } from 'valuelink'

...

// Instead of const [ name, setName ] = useState('')

const $name = useLink('');

```



Usage with React Component.



```javascript

import React from 'react'

// Instead of React.Component...

import { LinkedComponent } from 'valuelink'

...

// In a render, do

const $name = this.$at('name');

// Or, to link all the state members at once...

const state$ = this.state$();

```



Refer to the [databinding examples](/examples/databinding) and the [manual](/linked-controls/README.md) for the typical data binding scenarios.



### Create your own data bound controls



Use [linked-controls](/linked-controls) project as the starting boilerplate for your components.



### Create the binding to the custom state container



NestedLink is an abstraction of the data binding independent on both the particular control and the state container. The [default binding](/valuelink/src/component.ts) implemented

in the library is for the standard React state. It's fairly easy to create your own.



You need to subclass React.Component and make your own `$at` and `state$` methods.

You can either use `Link.value` inside to create links dynamically, or extend the `Link` as it's done in [/valuelink/src/component.ts](/valuelink/src/component.ts).



### Start hacking



![design](/images/valuelinks.jpg)



It's a very simple library written with TypeScript, there's no any magic inside (except some scary type annotations). If you want to play with the examples, fix the bug, or whatever:



`yarn` - installs the dependencies.



`yarn build` - compiles everything including examples.



## Release Notes

### 2.0



- IMPORTANT: Repository is converted to the monorepository based on yarn worspaces.

- IMPORTANT: `valuelink/tags.jsx` is moved to the dedicated package `linked-controls`.

- Complete support of new React Hooks API.

    - `useLink()` to create the state link.

    - `useIO()` to perform promised IO on mount.

    - `useLocalStorage()` to persist links to the local storage (loaded on mount, saved on unmount).

- $-notation for the link variables.

- New React.Component API (`this.linkAt -> this.$at`, `this.linkAll` -> `this.state$`)

- Group operations `Link.getValues()`, `Link.setValues()`, `Link.getErrors()`



### v1.6



React Hooks support.



- `useLink( initValue )` - create linked state.

- `setLinks({ lnk1, lnk2, ... }, json )` - bulk set link values from an object.

- `linksValues({ lnk1, lnk2, ... })` - extract values object from links.

- `linksErrors({ lnk1, lnk2, ... })` - extract errors object from links.



### v1.5



- `` can be used to bind the link to any of the standard controls expecting `value` and `onChange` props.



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![usedby](/images/usedby.png)