npm package: @kandor/kandor-react-native-form-builder
Description: Custom Form Builder for Private Distribution
Author: Brandon Krieger, Kandor
Latest version: 1.0.0

[![NPM Version](https://img.shields.io/npm/v/react-native-form-builder.svg?style=flat)](https://www.npmjs.com/package/react-native-form-builder)
# react-native-form-builder

## Features
- Generate Form Fields UI
- Manage, track state & values of fields
- Automatically manages focus to next field on submit (TextInput)
- Handle all keyboard related problems smartly
- Supports custom validations & nested forms
- Uses <a href="https://github.com/GeekyAnts/NativeBase">Nativebase</a> components

## Getting Started

- [Installation](#installation)
- [Basic Usage](#basic-usage)
- [Properties](#properties)
  + [Basic](#basic)
  + [Methods](#methods)
  - [Form Fields](#form-fields)
    + [Field Structure](#field-structure)
    + [Common Properties to all Fields](#common-properties-to-all-fields)
    - [Field Types](#field-types)
      + [TextInput](#textinput)
      + [Picker](#picker)
      + [Switch](#switch)
      + [Date](#date)
      + [Select](#select)
   + [Nested Forms](#nested-forms)
   + [Prefilling Form's Values](#prefill-form-values)
   + [Add Custom Validations](#add-custom-validations)
   + [Customize Your Form](#customize-your-form)
   + [Add custom components](#add-custom-components)
   + [Add custome error component](#add-custom-error-component)
- [Example](#example)

## Installation

```bash
$ npm i @kandor/react-native-form-builder --save
```

## Basic Usage

- Install `react-native` first

```bash
$ npm i react-native -g
```
- Initialization of a react-native project

```bash
$ react-native init myproject
```

- Then, edit `myproject/index.ios.js`, like this:
Example: Login Form consisting of three fields (username, password, country)

```jsx
import React, { Component } from 'react';
import { AppRegistry } from 'react-native';
import { View, Text, Button } from 'native-base';
import GenerateForm from 'react-native-form-builder';

const styles = {
  wrapper: {
    flex: 1,
    marginTop: 150,
  },
  submitButton: {
    paddingHorizontal: 10,
    paddingTop: 20,
  },
};
// These Fields will create a login form with three fields
const fields = [
  {
    type: 'text',
    name: 'user_name',
    required: true,
    icon: 'ios-person',
    label: 'Username',
  },
  {
    type: 'password',
    name: 'password',
    icon: 'ios-lock',
    required: true,
    label: 'Password',
  },
  {
    type: 'picker',
    name: 'country',
    mode: 'dialog',
    label: 'Select Country',
    defaultValue: 'INDIA',
    options: ['US', 'INDIA', 'UK', 'CHINA', 'FRANCE'],
  },
];
export default class FormGenerator extends Component {
  login() {
    const formValues = this.formGenerator.getValues();
    console.log('FORM VALUES', formValues);
  }
  render() {
    return (
      <View style={styles.wrapper}>
        <View>
          <GenerateForm
            ref={(c) => {
              this.formGenerator = c;
            }}
            fields={fields}
          />
        </View>
        <View style={styles.submitButton}>
          <Button block onPress={() => this.login()}>
            <Text>Login</Text>
          </Button>
        </View>
      </View>
    );
  }
}

AppRegistry.registerComponent('FormGenerator', () => FormGenerator);
```
## Properties
### Basic
| Prop  | Default  | Type | Description |
| :------------ |:---------------:| :---------------:| :-----|
| autoValidation | true | `bool` | if `false` then auto validation script will not run i.e formBuilder will not validate form data automatically. |
| onValueChange | N/A | `function` | Invoked every time after a field changes it's value |
| customValidation | N/A | `function` | This function will be triggered everytime before a field changes it's value, here you can write your custom validation script & set error accordingly. |
| customComponents | N/A | `object` | To define your custom type of components.|
| formData | N/A | `object` | To prefill the form values.|
| fields | `required` | `array` | Array of form fields. |
| scrollViewProps | N/A | `object` | Scrollview custom props. |
| errorComponent | N/A | `React Component` | Custom error display component. |

### Methods:
Currently, these methods are available in FormBuilder, you can access them by using ref property.

### getValues
To extract the values of form fields.
Returns: An object consisting of field values (fieldName: value).
for e.g
```
{
  username: 'brandon@kandor.io'
  password: 'Password'
}
```
### setValues
Forcefully set values for particular fields.<br/>
Parameters: An object of key value pairs(`name: value`).<br/>
name: Field name for which value has to be set.<br/>
value: Value for that particular field
For e.g
```
{ name1: value1, name2: value2, .....}
```
### resetForm
Reset Form values as well as errors.
### setToDefault
Forcefully set values to default for particular fields.
Parameters: An array of strings, where every string is the name of a field for which value has to be set as default value.
For e.g
```
[fieldName1, fieldName2, fieldName3 .....]
```

### Form Fields
### Field Structure
A field is an object which has the properties required to generate it.
It looks something like that :
```jsx
{
  type: 'text',
  name: 'user_name',
  label: 'Username'
}
```

### Common Properties to all Fields
These properties are applicable on all fields.

| Property  | Required  | Type | Description |
| :------------ |:---------------:| :---------------:| :-----|
| type | `yes` | `enum` only possible values are : { text, password, group, email, number, url, select, switch, date } | To define type of field. |
| name | `yes` | `string` | Every field should has a name which works as an unique identifier for that field. |
| label | `yes` | `string` | Field label to display. |
| editable | `No` | `bool` | To decide that whether a field is editable or not. |
| required | `No` | `bool` | Helps to decide if a field can has empty value or not. Doesn't work in case of `autoValidation = false` . |
| defaultValue | `No` | `Depends on field's type` | Sets the intial value for that field before the form initialization. |
| hidden | `No` | `bool` | If `true` then a field will not be displayed. |

### Field Types
### TextInput
Supports all these kind of types :-
text,
password,
email,
url,
number

#### Extra Properties
| Props  | Default | Type | Description |
| :------------ |:--------------- |:---------------| :-----|
| iconName | N/A | `string` | Sets the icon, you can use any icon name which is available in `react-native-vector-icons`|
| iconOrientaion | `left (default)` or `right` | `string` | Adjust icon orientation |
| props | N/A | `object` | Here you can define extra props which are applicable for react native TextInput Component. For e.g. { multiline: true, secureTextEntry : true .... }

#### Value Type : `String` ( Except for type `number` )

### Picker
`type: picker`
Uses native picker

#### Extra Properties
| Props  | Default | Type | Description |
| :------------ |:--------------- |:---------------| :-----|
| options (required) | N/A | `array` | An array of strings to define available options for e.g. ['CAR', 'BIKE', 'BICYCLE'] |
| props | N/A | `object` | Here you can define extra props which are applicable of react native Picker Component for e.g. { mode: 'dropdown', .... }

#### Value Type : `String`

#### Default Value Type :
You can set default value as a string which must be present in available options.
For e.g If options are ['CAR', 'BIKE', 'BICYCLE'] then you can define `defaultValue = 'BIKE'`

### Switch
`(type: switch)`
It's an implement of React Native `switch` component.

#### Value Type : `Boolean`

### Date
`(type: string)`

#### Extra Properties
| Props  | Default | Type | Description |
| :------------ |:--------------- |:---------------| :-----|
| mode | `datetime` | `string` | To define type of date picker, available values are `date, time, datetime` |
| maxDate | N/A | `string` or `JS Date object` | To define the maximum date can be select in date picker  |
| minDate | N/A | `string` or `JS Date object` | To define the minimum date can be select in date picker  |


#### Value Type : `String`
#### Default Value Type : `string` or `JS Date object`

### Select

#### Extra Properties
| Props | Required | Default | Type | Description |
| :------------| :------------ |:--------------- |:---------------| :-----|
| multiple | `No` | `false` | `bool` | To define that the field can accept multple values or not i.e user can select multiple values at a time or not. |
| objectType | `No` |  `false` | `string` | To define that the values can be of object or not.If `true`, then you need to specify `labelKey` & `primaryKey`  |
| labelKey | `Yes` if `objectType = true` | `N/A` | `string` | To define the key which value need to be used as label. |
| primaryKey | `Yes` if `objectType = true` |  `N/A` | `string` | To define the key which is unique in all objects.  |
| options | `Yes` |  `N/A` | array of `objects` or `strings` | An array of `objects` or `strings` containing all available options.|

#### Value Type : Array of `Strings` or `Objects`
#### Array of Strings
For e.g. `options = ['CAR', 'BIKE', 'BICYCLE']`
#### Array of Objects
If you're using array of objects then please don't forget to define these properties:
```jsx
objectType: true,
labelKey: 'name', // For Below example
primaryKey: 'id,  // For Below example
```
For e.g.
```
options: [
        {
          id: 1,
          name: 'CAR',
        },
        {
          id: 2,
          name: 'BIKE',
        },
        {
          id: 3,
          name: 'BICYCLE',
        },
      ]
```
#### Default Value Type : `string` or `JS Date object`
In case of object values:
```
defaultValue: [{
        id: 3,
        name: 'brandon',
        title: 'Founder/Principle',
      }],
 ```
In case of string values:
```
defaultValue: ['CAR', 'BIKE'],
```

## Nested Forms
`(type: group)`
Form Builder also supports nested forms, some times you need to wrap all of your form values in an object or we can say that you have some nested fields, in this case you can define `group` fields.
An example will better explain it:

```
{
      type: 'group',
      name: 'address',
      label: 'Address',
      fields: [
        {
          type: 'text',
          name: 'city',
          label: 'City',
        },
        {
          type: 'picker',
          name: 'country',
          label: 'Country',
          defaultValue: 'INDIA',
          options: ['US', 'INDIA', 'UK', 'CHINA', 'FRANCE'],
        },
      ],
    },
```
#### Value Type : `Object`

For above example the return value object will be something like that:
```
{ city: 'Indianapolis', country: 'United States' }
```
#### Default Value Type : `Object`

You can set default value for above example like that:
```
{ city: 'Newyork', country: 'US' }
```
## Prefill Form Values
This feature of formBuilder is very helpful in case of edit mode i.e if you want to edit the values of a form then you can easily prefill the form by using `formData` prop.<br/>
For e.g
```
formData = {
  first_name : 'Jamie',
  last_name: 'Lannister',
  house: 'Lannister',
  status: 'Slain'
}
```

## Custom Label for Inputs For Small Screens
- In some cases, where labels and values are both of signficant length, they will not fit in one line.
- Also, the label is not displayed after entering a value into a Text Input field, resulting in completed forms not showing the questions asked.
- If label is needed to be displayed, the prop, customTopLabel can be added to the props object, passed to the input. This must be a string.

## Add Custom Validations

It's very easy to add your custom validations & error messages with FormBuilder.All you need to do is define a function & pass it as `customValidation` prop.

For e.g.
```
 function validate(field) {
   let error = false;
   let errorMsg = '';
   if (field.name === 'username' && !(field.value && field.value.trim())) {
     error = true;
     errorMsg = 'Username is required';
   }
   if (field.name === 'password' && !(field.value && field.value.trim())) {
     error = true;
     errorMsg = 'Password is required';
   }
   return { error, errorMsg };
 }
```
Note: Always return an object which will have two entities `error` type of `boolean` & `errorMsg` type of `string`.

## Customize your form
- Eject Theme by running this command
```bash
node node_modules/@kandor/react-native-form-builder/ejectTheme.js
```
It will create a file named `form-theme.js` in your project's root folder.

Customize your theme.

Import theme from `form-them`.

Use it by passing as `theme` prop.
```
import theme from '../form-theme';
....
 <GenerateForm
  ref={(c) => { this.formGenerator = c; }}
  theme = {theme}
  ....
  />
```
## Add Custom Components
Build your custom type's components & handle them easily with the help of form builder.
Use the `customComponents` prop of form builder.
### Prototype
It's an object of key value pair where key will be the `type` of the component & value will be your custom Component.<br/><br/>
```customComponents = { type1: {component: ComponentName1, props: Props }, type2: {component: ComponentName2} .....}```

### How To Use
- Define your custom `type` in field's object.
- Form builder extends the props of your component by adding some extra props.
- You can also pass some extra props in your custom components.
- In your component you can access these props to handle the state of the field.

| Props | Type | Description |
| :------------| :------| :-----|
| attributes | `object` | In this prop you can access the field's attributes (value, error, errorMsg ....). |
| updateValue(fieldName, Value) | `function` | You need to use this method to update the value of the field |
| onSummitTextInput(fieldName) | `function`| If you're using TextInput then you can use this function to automatically manage the text input focus.For example you can define it in the `onSubmitEditing` prop of TextInput
| theme | `object` | Use the theme variables to style your component

## Add Custom Error Component
- Now you can use your custom error component to display error messages.
- In your custom component you will receive two props `attributes` & `theme` variables.
- You can access the error & error message as a property of the attributes object.