gandalf-validator

Determines who shall and shall not pass form validation in React

Note: This documentation is for version 1.X.X, for 0.X.X documentation, see README_v0.

Installation
Usage
Building Components for Gandalf
Contributing

Installation

npm install --save gandalf-validator

Usage

The Gandalf class extends React.Component, so we start by extending Gandalf.

import React from 'react';
import Gandalf from 'gandalf-validator';
 
class Form extends Gandalf {
  componentDidMount() {
    this.buildFields(fieldDefinitions);
  }
  ...
  render(){
    if (!this.areFieldsReady()) {
      return 'Loading...';
    }
    return (
      <form>
        ...
    ); 
  }
}
export default Form;

Gandalf expects the buildFields method to be called in the componentDidMount lifecycle method. buildFields takes a field definitions array as its only parameter. It also provides the areFieldsReady method to be used in the render method to show a loading state before all the fields are generated.

Field Definitions

Example

const fieldDefinitions = [
  {
    name: 'name',
    component: TextField,
    validators: ['required'],
    errorPropName: 'errorText',
    props: {
      hintText: 'Name',
    },
    debounce: 500,
  },
  {
    name: 'age',
    component: TextField,
    validators: ['required', 'numeric'],
    errorPropName: 'errorText',
    props: {
      hintText: 'Age',
    },
    debounce: 300,
  }
];

Options

Property	Type	Description
`name`	String	Field name
`component`	React Component	The component to render
`props`	Object	Props to pass to the component
`validators`	Array	List of validators to apply to the value
`errorPropName`	String	The name of the prop in `component` used to display errors (optional)
`errorPropIsBool`	Boolean	Whether the `errorPropName` expects a boolean instead of a string (optional)
`onChangeHandler`	Function	Specify a name for the change handler function, defaults to `onChange`
`getValueInOnChange`	Function	If the value in the onChange handler is something other than e.target.value, this function can get it. Takes (e, key, payload).
`children`	Array	Array of child React Components. Remember to add a `key` prop.
`debounce`	Integer	Milliseconds to delay validation, resets w/ each keystroke (optional)
`defaultValue`	Any	Default value for the component (optional)

Validators

Gandalf ships with several out of the box validations. Some are very simple, requiring only a string identifier. Others are more complex, requiring an object.

Simple

required
numeric
email

To enable a simple validator, add the string identifier to the validators prop.

validators: ['required', 'numeric', 'email']

Complex

minLength
maxLength
min
max
regex

Complex validators are objects with a name and value property.

validators: [{ name: 'minLength', value: 8 }, { name: regex, value: /[^0-9]/g }]

Simple + Complex

You can use both simple and complex validators on the same field.

validators: [
  'required',
  { name: 'minLength', value: 8 },
  { name: regex, value: /.+\s.+/g }
]

Custom Error Messages

Gandalf provides generic error messages by default, but you can pass your own to the Validator object. If you're using a simple validator, you can use an object with name and message fields as shown below.

validators: [
  { name: 'required', message: 'How dare you not fill this field?' }
  { name: 'minLength', value: 8, message: 'Your answer is too short! It must be at least 8 characters.' },
]

In Practice

import React from 'react';
import Gandalf from 'gandalf-validator';
import TextField from 'material-ui/TextField';
import { Input } from 'semantic-ui-react';
 
class Form extends Gandalf {
  componentDidMount() {
    const fieldDefinitions = [
      {
        name: 'firstName',
        component: TextInput,
        validators: ['required'],
        errorPropName: 'errorText',
        props: {
          autoComplete: 'given-name',
          label: 'First Name',
        },
        debounce: 300,
      },
      {
        name: 'lastName',
        component: TextInput,
        validators: ['required'],
        errorPropName: 'errorText',
        props: {
          autoComplete: 'family-name',
          label: 'Last Name',
        },
        debounce: 300,
      },
      {
        name: 'company',
        component: TextInput,
        validators: ['required'],
        errorPropName: 'errorText',
        props: {
          autoComplete: 'organization',
          label: 'Company Name',
        },
        debounce: 300,
      },
      {
        name: 'phone',
        component: TextInput,
        validators: [
          'required',
          {
            name: 'regex',
            value: /\D*([1-9]\d{2})(\D*)([1-9]\d{2})(\D*)(\d{4})\D*/,
            message: 'Please enter a valid phone number',
          },
        ],
        errorPropName: 'errorText',
        props: {
          autoComplete: 'tel',
          label: 'Phone #',
        },
        debounce: 700,
      },
      {
        name: 'availability',
        component: SelectField,
        validators: ['required'],
        errorPropName: 'errorText',
        getValueInOnChange: (e, key, value) => value,
        props: {
          hintText: 'Availability',
        },
        children: [
          <MenuItem key={1} value="Never" primaryText="Never" />,
          <MenuItem key={2} value="Every Night" primaryText="Every Night" />,
          <MenuItem key={3} value="Weeknights" primaryText="Weeknights" />,
          <MenuItem key={4} value="Weekends" primaryText="Weekends" />,
          <MenuItem key={5} value="Weekly" primaryText="Weekly" />,
        ],
      },
      {
        name: 'colour',
        component: Input,
        validators: ['required'],
        errorPropName: 'error',
        errorPropIsBool: true,
        props: {
          placeholder: 'Favourite Colour',
        },
        debounce: 300,
      },
      {
        name: 'email',
        component: TextField,
        validators: ['required', 'email'],
        errorPropName: 'errorText',
        props: {
          hintText: 'Email',
        },
        debounce: 300,
      },
    };
 
    this.buildFields(fieldDefinitions);
  }
}

Rendering

The buildFields method build your form inputs as puts them into this.state.fields. Each element is accessible via the value of its name property. Use the areFieldsReady method to show a loading state before all the fields are generated.

render() {
  const fields = this.state.fields;
  if (!this.areFieldsReady()) {
    return 'Loading...';
  }
 
  return (
    <form>
      <h1>My Form</h1>
      { fields.firstName.element } <br />
      { fields.lastName.element } <br />
      { fields.company.element } <br />
      { fields.phone.element } <br />
      { fields.availability.element } <br />
      { fields.colour.element } <br />
      { fields.email.element } <br />
 
      <button onClick={this.handleSubmit}>Submit</button>
    </form>
  );
}

Handling Form Submit

Gandalf provides two methods for getting form data:

// Returns form data, regardless of its validity
this.getFormData();
 
// If the form is valid, returns the form data, otherwise returns null
this.getCleanFormData();

Recommended submit handler implementation:

handleSubmit() {
  const data = this.getCleanFormData();
 
  // If form is invalid, all error messages will show automatically
  // So you can simply exit the function
  if (!data) return;
 
  // Handle valid data here
}

Checking Form State

Gandalf also privides two methods for checking the current state of the form:

// Not every element on the form has been touched - it may be invalid, but not all errors are triggered
// An element is not included in this list if it has an empty validators array
this.formHasPristineElements()
 
// Whether the form is currently valid. Use in combination with formHasPristineElements for reliable results
this.formIsValid()

It also provides a method to check if the form elements were built:

// Returns true if the buildFields() has been called and fields are created 
this.areFieldsReady();

Full Example

import React from 'react';
import Gandalf from 'gandalf-validator';
import TextField from 'material-ui/TextField';
import { Input } from 'semantic-ui-react';
 
class Form extends Gandalf {
  componentDidMount() {
    const fieldDefinitions = [
      {
        name: 'firstName',
        component: TextInput,
        validators: ['required'],
        errorPropName: 'errorText',
        props: {
          autoComplete: 'given-name',
          label: 'First Name',
        },
        debounce: 300,
      },
      {
        name: 'lastName',
        component: TextInput,
        validators: ['required'],
        errorPropName: 'errorText',
        props: {
          autoComplete: 'family-name',
          label: 'Last Name',
        },
        debounce: 300,
      },
      {
        name: 'company',
        component: TextInput,
        validators: ['required'],
        errorPropName: 'errorText',
        props: {
          autoComplete: 'organization',
          label: 'Company Name',
        },
        debounce: 300,
      },
      {
        name: 'phone',
        component: TextInput,
        validators: [
          'required',
          {
            name: 'regex',
            value: /\D*([1-9]\d{2})(\D*)([1-9]\d{2})(\D*)(\d{4})\D*/,
            message: 'Please enter a valid phone number',
          },
        ],
        errorPropName: 'errorText',
        props: {
          autoComplete: 'tel',
          label: 'Phone #',
        },
        debounce: 700,
      },
      {
        name: 'availability',
        component: SelectField,
        validators: ['required'],
        errorPropName: 'errorText',
        getValueInOnChange: (e, key, value) => value,
        props: {
          hintText: 'Availability',
        },
        children: [
          <MenuItem key={1} value="Never" primaryText="Never" />,
          <MenuItem key={2} value="Every Night" primaryText="Every Night" />,
          <MenuItem key={3} value="Weeknights" primaryText="Weeknights" />,
          <MenuItem key={4} value="Weekends" primaryText="Weekends" />,
          <MenuItem key={5} value="Weekly" primaryText="Weekly" />,
        ],
      },
      {
        name: 'colour',
        component: Input,
        validators: ['required'],
        errorPropName: 'error',
        errorPropIsBool: true,
        props: {
          placeholder: 'Favourite Colour',
        },
        debounce: 300,
      },
      {
        name: 'email',
        component: TextField,
        validators: ['required', 'email'],
        errorPropName: 'errorText',
        props: {
          hintText: 'Email',
        },
        debounce: 300,
      },
    };
 
    this.buildFields(fieldDefinitions);
  }
 
  handleSubmit() {
    const data = this.getCleanFormData();
 
    // If form is invalid, all error messages will show automatically
    // So you can simply exit the function
    if (!data) return;
 
    // Handle valid data here
  }
 
  render() {
    const fields = this.state.fields;
    
    if (!this.areFieldsReady()) {
      return 'Loading...';
    }
 
    return (
      <form>
        <h1>My Form</h1>
        { fields.firstName.element } <br />
        { fields.lastName.element } <br />
        { fields.company.element } <br />
        { fields.phone.element } <br />
        { fields.availability.element } <br />
        { fields.colour.element } <br />
        { fields.email.element } <br />
 
        <button
          onClick={() => this.handleSubmit()}
          disabled={() => this.formHasPristineElements() || !this.formIsValid()}
        >
          Submit
        </button>
      </form>
    );
  }
}

Building Components for Gandalf

Some component libraries provide inputs with built in error handling.

For example, Material UI TextFields provide an errorText prop that alters the component's appearance if it exists. Similarly, Semantic UI's Input component provides a boolean error prop that turns the input red if it exists.

But what if you want to build your own component for use with Gandalf? Turns out it's pretty easy.

React Native Example

React Native provides a TextInput component. It's very similar to an HTML input in regular React, with a few tiny differences. For example it exposes an onChangeText handler instead of an onChange handler for handling input changes.

But it has no build in error handling. So let's build it. We'll call it ValidatedTextInput.

import React from 'react';
import { View, Text, TextInput } from 'react-native';
 
const ValidatedTextInput = (props) => (
  <View>
    <View>
      <Text>{ props.title }</Text>
      <TextInput
        onChangeText={props.onChange}
        placeholder={props.placeholder}
      />
    </View>
    {!!props.error &&
    <View>
      <Text>
        { props.error }
      </Text>
    </View>
    }
  </View>
);

We know that we can define arbitrary props in the Fields Object. On top of those, Gandalf passes in an error prop (string) and an onChange handler (function).

We can use the existence of error to conditionally render the error message UI. The rest is as simple as passing props to TextInput.

Now we can use ValidatedTextInput in Gandalf:

import React from 'react';
import Gandalf from 'gandalf-validator';
import { View, Text, TouchableHighlight } from 'react-native';
 
import ValidatedTextInput from '../components/ValidatedTextInput';
 
class Form extends Gandalf {
  componentDidMount() {
    const fields = [
      {
        name: 'fName',
        component: ValidatedTextInput,
        getValueInOnChange: value => value,
        validators: ['required'],
        props: {
          title: 'First Name',
          placeholder: 'John Doe',
        },
        debounce: 300,
      },
    };
 
    this.buildFields(fields);
  }
 
  handleSubmit() {
    const data = this.getCleanFormData();
 
      // If form is invalid, all error messages will show automatically
      // So you can simply exit the function
      if (!data) return;
 
      // Handle valid data here
    }
 
  render() {
    const fields = this.state.fields;
    
    if (!this.areFieldsReady()) {
      return 'Loading...';
    }
 
    return (
      <View>
        { fields.fName.element }
 
        <TouchableHighlight onPress={this.handleSubmit}>
          <Text>Submit</Text>
        </TouchableHighlight>
      </View>
    );
  }
}

Contributing

File a Github Issue or fork this repo, make a PR and bump the version in the package.json file.

To build locally, use npm run build. This will transpile and uglify the library.

Running tests locally

You will need to add a .babelrc file in your local gandalf-validator directory. It is git ignored, as it can conflict with .babelrc files in projects using Gandalf.

.babelrc:

{
  "presets": ["es2015"]
}