@andydowell/use-form-state

FormState React Hook

The useFormState hook is a utility for managing form state in React applications. It provides functionality for tracking and validating form fields, as well as extracting form data in different formats. With useFormState, you can easily handle form interactions and ensure data integrity.

Installation

To install the use-form-state package, run the following command:

npm install @andydowell/use-form-state

Usage

Initializing the Form State

import { useFormState } from "@andydowell/use-form-state";

const formState = useFormState(formStateProps, options);

Before using the hook, you need to define the formStateProps. These props represent the structure of your form and include information such as default values, validation rules, and error messages.

Each field in the formStateProps is defined by a key-value pair, where the key is the name of the field and the value is an object with the following properties:

Property	Description	Type	Example
defaultValue	The default value for the form field.		""
isRequired	(Optional) Specifies whether the form field is required.	boolean
validator	(Optional) A function that validates the form field value. The first param is the input value, second param is the form state, which the value can be validated using other form field value.	(value, state) => boolean	(confirmPassword, state) => { return confirmPassword === state.password.value }
label	(Optional) Default as empty string ("").	string	'Email'
helperText	(Optional) Text that provides additional information or guidance for the form field.	string	'Please enter a valid email'
errorMessage	(Optional) An object that defines error messages for specific error types.	{format: string, required: string}	{ format: 'Invalid format', required: 'This field is required' }

The second parameter options is an object with the following properties:

Property	Type	Description
errorUpdateDelayInSeconds	number	(Optional) Specifies the delay in seconds before the error type is updated. Default is 0.5.

You can see an example of formStateProps and options in the Example section.

API

The useFormState hook returns an object with the following properties and methods:

const { state, set, checkIfAllValid, extractStateValue, reset } = useFormState(formStateProps, options);

The state object contains the current values and validation status of each form field.
The set function allows you to update the form field values.
The checkIfAllValid function checks if all fields are valid.
The extractStateValue function extracts the form data in the specified format.
The reset function resets the form to its initial state.

Form State

Each form field in the state object is represented by an object with the following properties:

Property	Description	Example Usage	Example Output
value	The current value of the form field.	state.email.value
isValid	Indicates whether the value of the form field is valid. Required fields are considered valid if they are filled. If a validator is provided, the value will be validated against the validator function.	state.email.isValid
isInteracted	Indicates whether the form field has been interacted with (user has changed the value).	state.email.isInteracted
isRequired	Indicates whether the form field is required.	state.email.isRequired
label	The label of the form field.	state.email.label	'Email'
helperText	A helper text that provides additional information or instructions for the form field.	state.email.helperText
error	An object that represents an error associated with the form field. It has two properties: type (the type of error) and message (the error message). If there is no error, this property will be undefined.	state.email.error state.email.error?.type state.email.error?.message	{ type: "required", message: "Please enter your email address" }

error is not updated immediately when the value of a form field changes. Instead, it is updated after a delay (default is 0.5 seconds) to prevent the error message from flashing when the user is typing. If the field is not interacted with, the error will not be updated. Running checkIfAllValid({ updateErrorType: true }) will update all errors immediately.

Updating Form Field Values

To update a form field value, use the set function:

set(key, value, setInteracted);

Parameter	Type	Description	Example
key	string	The key of the field in the form state.	'email'
value	(type of the field value)	The new value to be set for the field.	'[e-mail]'
setInteracted	boolean	(Optional) Indicates whether the field should be marked as interacted. Default is true.	false

You can see an example of set in the Example section.

Checking Form Field Validity

You can check the validity of individual form fields by accessing the isValid property in the state object:

const isEmailValid = state.email.isValid;

Checking Overall Form Validity

To check if the entire form is valid, use the checkIfAllValid function:

const isFormValid = checkIfAllValid(options);

The options parameter is an object with the following properties:

Parameter	Type	Description
updateErrorType	boolean	(Optional) Specifies whether the error types of all fields should be updated. Default is true.

The validation will check all form fields based on their defined rules and update their validation status and error messages accordingly.
You can see an example of checkIfAllValid in the Example section.

Extracting Form Data

You can extract the form data in different formats using the extractStateValue function. Currently, two formats are supported: 'object' and 'formdata'.

Example:
To extract the form data as an object:

const dataObject = extractStateValue({ format: "object" });

To extract the form data as FormData:

const formData = extractStateValue({ format: "formdata" });

You can see an example of extractStateValue in the Example section.

Resetting the Form

To reset the form to its initial state, use the reset function:

reset();

This will clear all form field values and reset their validation status.
You can see an example of reset in the Example section.

Example

const newUser = useFormState({
  email: {
    defaultValue: "",
    isRequired: true,
    validator: value => {
      return value.includes("@");
    },
    label: "Email",
    helperText: "Please enter your email address",
    errorMessage: {
      required: "Email address is required",
      format: "Email address is invalid",
    },
  },
  password: {
    defaultValue: "",
    isRequired: true,
    label: "Password",
    helperText: "Please enter your password",
    errorMessage: {
      required: "Password is required",
    },
  },
  confirmPassword: {
    defaultValue: "",
    isRequired: true,
    validator: (value, formState) => {
      return value === formState.password.value;
    },
    label: "Confirm Password",
    helperText: "Please confirm your password",
    errorMessage: {
      required: "Password is required",
      format: "Password does not match",
    },
  },
});

// ---------------------------------

const onSubmit = async e => {
  e.preventDefault();
  if (!newUser.checkIfAllValid()) return;

  const formdata = newUser.extractStateValue({ format: "formdata" });
  // ... Submit formdata to server
};

// ---------------------------------

const { email, password, confirmPassword } = newUser.state;

<form onSubmit={onSubmit}>
  <div>
    <Input value={email.value} onChange={e => newUser.set("email", e.target.value)} />
    <p>{email.error?.message || email.helperText}</p>
  </div>
  <div>
    <Input type="password" value={password.value} onChange={e => newUser.set("password", e.target.value)} />
    <p>{password.error?.message || password.helperText}</p>
  </div>
  <div>
    <Input
      type="password"
      value={confirmPassword.value}
      onChange={e => newUser.set("confirmPassword", e.target.value)}
    />
    <p>{confirmPassword.error?.message || confirmPassword.helperText}</p>
  </div>
  <button type="submit">Submit</button>
  <button type="reset" onClick={newUser.reset}>
    Reset
  </button>
</form>;

License

This package is open source and available under the MIT License.