Core Concepts

Validation

Ensure data integrity with CanxJS's powerful validation system. Use simple inline validation or dedicate FormRequest classes for complex logic.

Basic Validation

The validate helper provides a quick way to validate arbitrary data against a set of rules.

basic-validation.ts

1import { validate } from "canxjs";
2
3app.post("/users", async (req, res) => {
4  const data = await req.body();
5
6  const rules = {
7    name: ["required", "string", "min:3"],
8    email: ["required", "email"],
9    age: ["number", "min:18"],
10    role: ["in:admin,user,editor"]
11  };
12
13  const validation = validate(data, rules);
14
15  if (!validation.valid) {
16    return res.status(422).json({
17      error: "Validation Failed",
18      details: Object.fromEntries(validation.errors)
19    });
20  }
21
22  // Use validated data
23  const user = await User.create(validation.data);
24  return res.json(user);
25});

Form Requests

For more complex scenarios, Form Requests encapsulate validation and authorization logic in a single class, keeping your controllers clean.

src/requests/CreateUserRequest.ts

1// src/requests/CreateUserRequest.ts
2import { FormRequest } from "canxjs";
3
4export class CreateUserRequest extends FormRequest {
5  /**
6   * Determine if the user is authorized to make this request.
7   */
8  authorize(): boolean {
9    // Check permissions, roles, etc.
10    return true; 
11  }
12
13  /**
14   * Get the validation rules that apply to the request.
15   */
16  rules() {
17    return {
18      name: ["required", "string", "min:3"],
19      email: ["required", "email", "unique:users,email"],
20      password: ["required", "string", "min:8", "confirmed"],
21    };
22  }
23
24  /**
25   * Custom error messages (optional)
26   */
27  messages() {
28    return {
29      "email.unique": "This email is already registered.",
30      "password.confirmed": "Passwords do not match."
31    };
32  }
33}

Using in Controllers

Use the @ValidateWith decorator to automatically validate requests before they hit your controller method.

src/controllers/UserController.ts

1// src/controllers/UserController.ts
2import { Controller } from "canxjs/controller";
3import { ValidateWith } from "canxjs";
4import { CreateUserRequest } from "../requests/CreateUserRequest";
5
6export class UserController extends Controller {
7  
8  @ValidateWith(CreateUserRequest)
9  async store(req: CanxRequest, res: CanxResponse) {
10    // Code execution only reaches here if validation passes.
11    
12    // Get validated data safely
13    const data = req.context.get("validated");
14    
15    const user = await User.create(data);
16    return res.status(201).json(user);
17  }
18}

Available Rules

requiredField must be present and not empty

stringMust be a string

numberMust be a number

booleanMust be true or false

emailMust be a valid email format

min:valueMinimum length (string) or value (number)

max:valueMaximum length (string) or value (number)

in:foo,barMust be one of the given values

urlMust be a valid URL

alphaOnly alphabetic characters

alphanumOnly alphanumeric characters

confirmedField must match {field}_confirmation

Next Steps

Now that your data is safe, learn how to store it in the database.