check-some

Component to help with form validation in react

Our pain points

When dealing with forms in react, forms with validation can involve a lot of code duplication. If you add a required field to your form, you need to add the input for the new field, add logic to check if there is a valid value, disable the submit button until there is a valid value, show a validation error by the field if they leave the field blank, and maybe change logic to show a cancel button if the field has changed.

This can become quite a bit of work to add a single field and if you miss a spot your form could act inconsistently (i.e. Your submit button could be enabled when it's not supposed to).

Our solution

This component receives the values and validation rules as props and renders your validated form using render props. The CheckSome component performs all the data validation and passes form state (such as valid or changed) to the form. The CheckSome.Field component accepts a render prop to render a specific field along with any validation errors and whether the field has been touched yet. This solution abstracts the validation logic while keeping flexibility for how to render error messages.

Installation

npm install --save check-some

or

yarn add check-some

Usage

import React, {Component} from 'react';
import CheckSome from 'check-some';

const required =  => value => {
  return value || value === 0 ? null : {required: {}};
};

class Form extends Component {
  render() {
    return (
      <CheckSome values={{name: this.state.name}} rules={{name: [required]}}>
        {({valid, changed}) => (
          <form>
            <CheckSome.Field name="name">
              {({value, errors, valid, touched}) => (
                <div className="field">
                  <label>
                    <input value={value} onChange={this.updateName}/>
                    {valid ? '👍' : '👎'}
                    {touched &&
                      errors &&
                      errors.required && <div className="error">Name is required.</div>}
                  </label>
                </div>
              )}
            </CheckSome.Field>

            {changed && <button onClick={this.resetForm}>Cancel</button>}
            <button onClick={this.submit} disabled={!valid || !changed}>
              Submit
            </button>
          </form>
        )}
      </CheckSome>
    );
  }
}

Error descriptions

Validation rules are defined as functions that take the value of a field and return null (if the field is valid) or an object containing any information that could be important for showing an error message. For example, a number field that is required and needs to be greater than 5, but has a value of 2 could be:

{
  required: null,
  greaterThanFive: {value: 2},
}

You could then use this to render a cusomized error message

{errors && errors.greaterThanFive && (
  <div>Value needs to be greater than 5, but was {errors.greaterThanFive.value}.</div>
)}

Components

CheckSome

Props

values - Object containing all the values of the form

{[key:string]: any}

rules - Object containing rules for all values (keys should match values set in values)

{[key:string]: null | {[errorName:string]: Object}}

initialValues (optional) - Object containing values to check against when finding out if form has changed

{[key:string]: any}

children - Render prop for rendering the form

(props: ChildProps) => React.Node

ChildProps (Props that will be passed to the render prop for CheckSome)

valid - If all the validation rules have passed

boolean

changed - If all the values have changed since the component mounted (or if the same as props.initialValues if set)

boolean

errors - Description of all the validation errors by field

{
  [key:string]: null | {[errorName:string]: Object}
}

CheckSome.Field

Props

name - The field to render (needs to match a key in values passed to CheckSome)

children - Render prop for rendering the field

(props: ChildProps) => React.Node

ChildProps

value - The value passed in values of CheckSome that matches the name set in CheckSome.Field

any

errors - Description of the validation errors for the field

null | {[errorName:string]: Object}

valid - If the validation rules for the field have passed

boolean

touched - If the field has been focused and blured

boolean

License

MIT