Remix form class-validator

Simple helper to parse Remix FormData and validate them using class-validator.

Features

• Server-side FormData parsing and validation using class-validator
• Provides typesafe access to parsed parameters and validation errors
• Support for arrays and nested attributes

Usage

Start by defining the DTO class that will hold your parameters, and the respective validations using class-validator:

class PersonDto {
  @IsNotEmpty()
  @MinLength(2)
  name: string;
  @Min(0)
  @Max(150)
  age: number;
}

Declare the route action and use parseRequestParams to parse and validate your parameters into your declared DTO:

const action: ActionFunction = async ({ request }) => {
  const params = await parseRequestParams(request, PersonDto);

  if (params.errors) {
    console.log("Form data is invalid", { errors: params.errors });
  } else {
    console.log("Form data is valid", { data: params.data });
  }

  return json(params);
};

Finally you just need to declare your form and use useActionData to access any errors resulting from validating your DTO.

type ActionData = ParseRequestParamsReturn<PersonDto>;

const SimpleForm = () => {
  const actionData = useActionData<ActionData>();

  return (
    <Form style={{ maxWidth: 400 }} method="post">
      <Input name="name" label="Name:" defaultValue={actionData?.data.name} />
      <InputError errors={actionData?.errors?.name} />
      <Input name="age" label="Age:" defaultValue={actionData?.data.age} />
      <InputError errors={actionData?.errors?.age} />
      <button type="submit" style={{ marginTop: "1rem" }}>
        Submit
      </button>
    </Form>
  );
};

Installation

To install simply run the following command:

$ npm install --save remix-form-class-validator

Because this library uses class-transformer you will need to import the reflect-metadata shim. On your entry.server.tsx file add the following import statement to import reflect-metadata:

// entry.server.tsx
import "reflect-metadata";

Configure Typescript

Because class-validator relies on annotations to perform validations, you should add the following to your tsconfig.json:

{
  // ...
  "compilerOptions": {
    // ...
    "strictPropertyInitialization": false,
    "experimentalDecorators": true
    // ...
  }
  // ...
}

Examples

You can check some example apps on the examples folder.