Form validation component to connect React.js to HTML5 Constraint Validation API πŸ’₯
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README.md

React-html5-form

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With the package you don't need to re-create form validation logic every time. Instead you take full advantage of HTML5 Constraint Validation API. Besides the package expose no custom input components, instead it provides wrapper InputGroup, which binds inputs (according to configuration) in the children DOM nodes. Thus you can go with both HTML controls and 3rd-party input components.

React meets HTML Form Validation

Highlights

  • Input implementation agnostic, can be used any arbitrary input controls (HTML or 3rd-party React components)
  • Standard HTML5 syntax for validation constraints (like <input type="email" required maxLength="50" ... />)
  • Can be extended with custom validators (again by using standard HTML5 API)
  • Can be setup for custom validation messages per input/ValidityState.Property
  • Form and input groups expose validity states, so you can use it to toggle scope error messages.
  • Form and input groups expose reference to own instances for children DOM nodes. So you can, for example, subscribe for input event and run input group validation (e.g. see On-the-fly validation)
  • Can maintain form state both ways: with React Context and Redux

Overview

With Form we define scope of the form. The component exposes parameters valid, error and form. The first reflects actual validity state according to states of registered inputs. The second contains error message (can be set using API). The last one is instance of the component and provides access to the API. With InputGroup we define a fieldset that contains one or more semantically related inputs (e.g. selects day, month, year usually go togather). The group expose valid, error, errors and inputGroup variables on children Nodes. So we can automatically toggle group error message and content classList depending on them. We register inputs within InputGroup with validate prop. There we can specify a validator function, which will extend HTMP5 form validation logic. Very easily we can provide mapping for standard validation message (translate prop).

react-html5-form in a single picture

Installation

npm i react-html5-form

Demo

You can see the component in action at LIVE DEMO πŸ“Ί

  • source code of example with HTML elements for inputs (styled with Bootstrap 4)
  • source code of example with read-made components for inputs (styled with MaterialUI.Next)
  • source code of example with connection to Redux

Form

Represents form

import { Form } from "react-html5-form";

Props

  • <Function> onSubmit - (OPTIONAL) form submit handler
  • <Function> onMount - (OPTIONAL) callback that gets invoked in componentDidMount(), it receives component instance as parameter
  • <Function> onUpdate - (OPTIONAL) callback that gets invoked when form ready (all input groups registered) and when it changes validity state. It's intended to be used with Redux to update tree state
  • any attributes of Form HTML element

API

  • scrollIntoViewFirstInvalidInputGroup() - scroll first input group in invalid state into view (happens automatically onSubmit)
  • checkValidityAndUpdateInputGroups() - check form validity and update every input group
  • checkValidityAndUpdate() - check form validity and update only form state (without updating input groups)
  • setError( message = "") - set form scope error message
  • submit() - submit form
  • getRef() - get Ref instance pointed to the generated FORM element. Thus if you need to access the DOM node, you go with form.getRef().current
  • debugInputGroups( inx = null ) - get debug info about all registered inputs, or one matching given index

Scope parameters

  • <String> error - error message set with setError()
  • <Boolean> valid - form validity state
  • <Boolean> pristine - true if user has not interacted with the form yet.
  • <Boolean> submitting - true while form is being processed on submission
  • <Boolean> submitted - true after form submitted
  • <React.Component> form - link to the component API

State properties valid, pristine, submitting, submitted are also available as element data-attributes e.g. data-submitting="false"

Defining component

import React from "react";
import { render } from "react-dom";
import { Form } from "react-html5-form";

const MyForm = props => (
  <Form id="myform">
  {({ error, valid }) => (
      <>
      Form content
      </>
    )}
  </Form>
);

render( <MyForm />, document.getElementById( "app" ) );

<Form> creates <form noValidate ..> wrapper for passed in children. It delegates properties to the produced HTML Element. For example specified id ends up in the generated form.

Accessing Form API

async function onSubmit( form ) {
  form.setError("Opps, a server error");
  return Promise.resolve();
};

const MyForm = props => (
  <Form onSubmit={onSubmit} id="myform">
  {({ error, valid, pristine, submitting, form }) => (
      <>
      { error && (<div className="alert alert-danger" role="alert">
            <strong>Oh snap!</strong> {error}
          </div>)
      }
      Form content

      <button disabled={ ( pristine || submitting ) } type="submit">Submit</button>

      </>
    )}
  </Form>
);

The API can be accessed by form reference. Besides, any handler passed through onSubmit prop gets wrapped. The component calls setState for checkValidity prior calling the specified handler. From the handler you can access the API by reference like form.setError. What is more, we disable submit button until the user first interaction with the form and on form submission (onSubmit is an asynchronous function / Promise; as it resolves the state property submitting` set in false).

InputGroup

InputGroup defines scope and API for a group of arbitrary inputs registered with validate prop. InputGroup exposes in the scope parameters that can be used to toggle group validation message(s), group state representation and to access the component API

import { Form, InputGroup } from "react-html5-form";

Props

  • <Object|Array> validate - (REQUIRED) register inputs to the group. Accepts either array of input names (to match [name=*]) or plain object out of pairs name: custom validator
// Group of a single input
<InputGroup validate={[ "email" ]} />
// Group of multiple inputs
<InputGroup validate={[ "month", "year" ]} />
// Custom validator
<InputGroup validate={{
          "vatId": ( input ) => {
            if ( !input.current.value.startsWith( "DE" ) ) {
              input.setCustomValidity( "Code must start with DE" );
              return false;
            }
            return true;
          }
        }}>
  • translate - (OPTIONAL) set custom messages for validation constraints (see ValidityState Properties)
     <InputGroup
              ...
              translate={{
                firstName: {
                  valueMissing: "C'mon! We need some value",
                  patternMismatch: "Please enter a valid first name."
                }
              }}>
    • tag - (OPTIONAL) define tag for the generated container HTML element (by default div)
    <InputGroup tag="fieldset" ... />
    • <Function> onMount - (OPTIONAL) callback that gets invoked in componentDidMount(), it receives component instance as parameter
    • <Function> onUpdate - (OPTIONAL) callback that gets invoked when form ready (all input groups registered) and when it changes validity state. It's intended to be used with Redux to update tree state
    • any attributes of HTML element

    API

    • checkValidityAndUpdate() - run checkValidity() and update the input group according to the actual validity state
    • getInputByName( name ) - access input fo the group by given input name
    • getValidationMessages() - get list of all validation messages within the group
    • checkValidity() - find out if the input group has not inputs in invalid state
    • getRef() - get Ref instance pointed to the generated element. Thus if you need to access the DOM node, you go with inputGroup.getRef().current

    Scope parameters

    • <String> error - validation message for the first invalid input
    • <String[]> errors - array of validation messages for all the inputs
    • <Boolean> valid - input group validity state (product of input states)
    • <Boolean> pristine - true if user has not interacted with the form yet.
    • <React.Component> inputGroup - link to the component API

    Basic use

      <InputGroup
        tag="fieldset"
        validate={[ "email" ]}
        translate={{
          email: {
            valueMissing: "C'mon! We need some value"
          }
        }}>
      {({ error, valid }) => (
    
              <div className="form-group">
              <label htmlFor="emailInput">Email address</label>
                <input
                  type="email"
                  required
                  name="email"
                  className={`form-control ${!valid && "is-invalid"}`}
                  id="emailInput"
                  placeholder="Enter email" />
    
                  { error && (<div className="invalid-feedback">{error}</div>)  }
              </div>
      )}
      </InputGroup>

    Here we define an input group with registered input matching [name=email]. We also specify a custom message for ValidityState.valueMissing constraint. It means that during the validation the input has no value while having constraint attribute required the input group receive validation message "C'mon! We need some value" in scope parameter error.

    Custom validators

          <InputGroup validate={{
              "vatId": ( input ) => {
                if ( !input.current.value.startsWith( "DE" ) ) {
                  input.setCustomValidity( "Code must start with DE." );
                  return false;
                }
                return true;
              }
            }}>
            {({ error, valid }) => (
              <div className="form-group">
                <label htmlFor="vatIdInput">VAT Number (optional)</label>
                <input
                  className={`form-control ${!valid && "is-invalid"}`}
                  id="vatIdInput"
                  name="vatId"
                  placeholder="Enter VAT Number"/>
    
                { error && (<div className="invalid-feedback">{error}</div>)  }
    
              </div>
            )}
          </InputGroup>

    Here we define a custom validator for vatId input (via validate prop). The validator checks if the current input value starts with "DE". If it dosn't we apply setCustomValidity method to set the input (and the group) in invalid state (the same as of HTML5 Constraint validation API).

    Group with multiple inputs

    const validateDateTime = ( input ) => {
      if ( input.current.value === "Choose..." ) {
          input.setCustomValidity( `Please select ${input.current.title}` );
          return false;
      }
      return true;
    };
        <InputGroup validate={{ "day": validateDateTime, "month": validateDateTime }}>
            {({ errors, valid }) => (
              <div className="form-group">
    
              <div className="form-row">
                <div className="form-group col-md-6">
                   <label htmlFor="selectDay">Day</label>
                   <select name="day" id="selectDay" title="Day" className={`form-control ${!valid && "is-invalid"}`}>
                      <option>Choose...</option>
                      <option>...</option>
                   </select>
                </div>
                <div className="form-group col-md-6">
                  <label htmlFor="selectMonth">Month</label>
                  <select name="month" id="selectMonth"  title="Month" className={`form-control ${!valid && "is-invalid"}`}>
                      <option>Choose...</option>
                      <option>...</option>
                  </select>
                </div>
              </div>
    
              { errors.map( ( error, key ) => ( <div key={key} className="alert alert-danger">{error}</div> )) }
    
              </div>
            )}
        </InputGroup>

    On validation we receives errors array that contains validation messages for all the inputs registered in the group. So we can display the messages within the group container.

    On-the-fly validation

    Let's first define the onInput event handler:

    const onInput = ( e, inputGroup ) => {
      inputGroup.checkValidityAndUpdate();
    };

    We use checkValidityAndUpdate method to actualize validity state and update the component.

    Now we subscribe the component:

        <InputGroup
              validate={[ "firstName" ]}
              translate={{
                firstName: {
                  patternMismatch: "Please enter a valid first name."
                }
              }}>
            {({ error, valid, inputGroup }) => (
              <div className="form-group">
                <label htmlFor="firstNameInput">First Name</label>
                <input
                  pattern="^.{5,30}$"
                  required
                  className={`form-control ${!valid && "is-invalid"}`}
                  id="firstNameInput"
                  name="firstName"
    
                  onInput={( e ) => onInput( e, inputGroup, form ) }
                  placeholder="Enter first name"/>
    
                { error && (<div className="invalid-feedback">{error}</div>)  }
              </div>
            )}
        </InputGroup>

    Here while assigning event handler inline we delegate the instance of component to earlier created onInput function like onInput={( e ) => onInput( e, inputGroup ) }. Thus we can operate it when responding to the event.

    Input

    Represents input element within input group scope.

    API

    • current - input HTML element
    • setCustomValidity( message = "" ) - set the input in invalid state
    • checkValidity() - returns boolean truthy when all the input in valid state
    • getValidationMessage() - get validation message considering assigned custom message if any

    Connecting to Redux store

    The package exposes reducer html5form, so one can connect form/input group/input states to the store:

    import React from "react";
    import { render } from "react-dom";
    import { createStore, combineReducers } from "redux";
    import { Provider } from "react-redux";
    
    import { App } from "./Containers/App.jsx";
    import { html5form } from "react-html5-form";
    
    const appReducer = combineReducers({
      html5form
    });
    
    // Store creation
    const store = createStore( appReducer );
    
    render( <Provider store={store}>
      <App />
     </Provider>, document.getElementById( "app" ) );
    
    

    Thus we get package-specific state tree in the store:

    react-html5-form and Redux

    • See full example here