FormKit is a flexible and powerful React form handling component that simplifies form management in React applications. It provides an intuitive API for handling form submissions, data management, and server interactions.

Features

• 🚀 Easy form state management
• 📡 Built-in API integration
• ⚡ Custom fetch support
• 🔄 Automatic form data handling
• 🎯 TypeScript support
• 🎨 Flexible child component rendering
• 🔒 Automatic loading state management
• 🔌 Third-party component integration

Installation

npm install formkit-react

yarn add formkit-react

Basic Usage

import { FormKit } from "formkit-react";

interface LoginForm {
  email: string;
  password: string;
}

function LoginComponent() {
  return (
    <FormKit<LoginForm>
      url="/api/login"
      onSuccess={(response) => console.log("Login successful:", response)}
      onError={(error) => console.error("Login failed:", error)}
    >
      <input name="email" type="email" placeholder="Email" />
      <input name="password" type="password" placeholder="Password" />
    </FormKit>
  );
}

Props

| Prop | Type | Description | | ------------- | ---------------------------------------- | ------------------------------------------------ | | url | string | API endpoint for form submission | | action | "POST" \| "PUT" \| "DELETE" \| "PATCH" | HTTP method for the request (default: "POST") | | onSubmit | (data: T) => void | Callback before form submission | | onSuccess | (response: any) => void | Callback on successful submission | | onError | (error: any) => void | Callback on submission error | | initalData | T & Record<string,any> | Initial form data | | customFetch | (data: T) => Promise<any> | Custom fetch function | | submitText | string | Text for submit button (default: "Submit") | | loadingText | string | Text while submitting (default: "Submitting...") | | defaultSubmitBtn | boolean | Show/hide default submit button (default: true) |

useFormKit Hook

FormKit provides a useFormKit hook to manage form state and interactions programmatically.

Usage

import { useFormKit } from "formkit-react";

interface ProfileForm {
  username: string;
  bio: string;
}

function ProfileFormComponent() {
  const { isLoading, error, reset } = useFormKit();

  return (
    <form>
      <button type="button" onClick={() => reset()}>Reset Form</button>
      <button type="submit" disabled={isLoading}>
        {isLoading ? "Updating..." : "Update Profile"}
      </button>
      {error && <p className="error">{String(error)}</p>}
    </form>
  );
}

Hook Return Values

| Return Value | Type | Description | | ------------- | ----------------------------- | -------------------------------------------------- | | isLoading | boolean | Indicates if the form is being submitted | | error | unknown | Error object if submission fails | | reset | (params?: any) => void | Function to reset the form state |

Form Controllers

FormKit provides a FormKitController component that makes it easy to integrate third-party form components. This controller handles the value management and data synchronization with the main form.

Controller Usage

import { FormKit } from "formkit-react";
import { FormKitController } from "formkit-react/controller";
import DatePicker from "react-third-party-datepicker";
import Select from "react-third-party-select";

interface MyFormData {
  date: Date;
  options: { value: string; label: string }[];
}

function MyForm() {
  return (
    <FormKit<MyFormData>
     url="/api/submit">
      {/* DatePicker Integration */}
      <FormKitController
        name="date"
        render={({ value, onChange }) => (
          <DatePicker selected={value} onChange={onChange} />
        )}
      />

      {/* React-Select Integration */}
      <FormKitController
        name="options"
        render={({ value, onChange }) => (
          <Select
            value={value}
            onChange={onChange}
            options={[
              { value: "option1", label: "Option 1" },
              { value: "option2", label: "Option 2" },
            ]}
            isMulti
          />
        )}
      />
    </FormKit>
  );
}

Controller Props

The FormKitController component accepts the following props:

interface ControllerProps<T = any> {
  name: string; // Field name in the form data
  render: (props: {
    value: T;
    onChange: (value: T) => void;
  }) => React.ReactElement;
}

Custom Component Integration

You can integrate any third-party component that accepts value and onChange props:

// Example with a custom Rich Text Editor
<FormKitController
  name="content"
  render={({ value, onChange }) => (
    <RichTextEditor
      value={value}
      onChange={onChange}
      toolbar={["bold", "italic"]}
    />
  )}
/>

Type Safety

The controller is fully typed and supports generic types:

interface EditorValue {
  content: string;
  format: "html" | "markdown";
}

<FormKitController<EditorValue>
  name="editor"
  render={({ value, onChange }) => (
    <Editor
      value={value.content}
      format={value.format}
      onChange={(content) => onChange({ content, format: "html" })}
    />
  )}
/>;

Advanced Usage

Custom Fetch Handling

interface UserForm {
  username: string;
  email: string;
}

function UserRegistration() {
  const handleCustomFetch = async (data: UserForm) => {
    // Example of custom API integration
    const response = await fetch("https://api.example.com/users", {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        Authorization: `Bearer ${localStorage.getItem("token")}`,
      },
      body: JSON.stringify(data),
    });

    if (!response.ok) {
      throw new Error("Registration failed");
    }

    return response.json();
  };

  return (
    <FormKit<UserForm>
      customFetch={handleCustomFetch}
      onSuccess={(response) => console.log("Success:", response)}
      onError={(error) => console.error("Error:", error)}

    >
      <input name="username" type="text" placeholder="Username" />
      <input name="email" type="email" placeholder="Email" />
      <button type="submit">Register</button>
    </FormKit>
  );
}

With Initial Data

interface ProfileForm {
  username: string;
  bio: string;
}

function ProfileEditor() {
  const initialData: ProfileForm = {
    username: "johndoe",
    bio: "Hello world!",
  };

  return (
    <FormKit<ProfileForm> url="/api/profile" action="PATCH" initalData={initialData}>
      <input name="username" type="text" />
      <textarea name="bio" />
    </FormKit>
  );
}

TypeScript Support

FormKit is written in TypeScript and provides full type safety. You can specify the form data type using generics:

interface MyFormData {
  name: string;
  email: string;
  age: number;
}

<FormKit<MyFormData>
  url="/api/submit"
  onSubmit={(data) => {
    // data is typed as MyFormData
    console.log(data.name); // TypeScript knows this exists
  }}
>
  {/* form fields */}
</FormKit>;

Error Handling

FormKit provides comprehensive error handling through the onError prop:

<FormKit
  url="/api/submit"
  onError={(error) => {
    if (error.message === "Network response was not ok") {
      // Handle network errors
    }
    // Handle other errors
  }}
>
  {/* form fields */}
</FormKit>

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.