Validation

The client automatically validates request parameters, query strings, and request bodies using Zod schemas.

Automatic Validation

When you make a request, the client automatically validates:

1. Path parameters - Validated against the params schema
2. Query parameters - Validated against the query schema
3. Request body - Validated against the body schema
4. Response data - Validated against the output schema

const result = await client.post("/users", {
  body: {
    name: "Alice",
    email: "invalid-email", // ❌ This will throw ValidationError
  },
});

Validation Errors

If validation fails, the client throws a ValidationError:

import { ValidationError } from "@alt-stack/http-client-fetch";

try {
  await client.get("/users/{id}", {
    params: { id: 123 }, // ❌ Should be string
  });
} catch (error) {
  if (error instanceof ValidationError) {
    console.error("Validation failed:", error.message);
    console.error("Validation errors:", error.validationErrors);
  }
}

The ValidationError includes:

• message: Human-readable error message
• validationErrors: Validation error details from Zod
• endpoint: The endpoint that failed validation
• method: The HTTP method that failed validation

Type Safety

TypeScript ensures you pass the correct types at compile time:

// ✅ TypeScript knows this is correct
await client.get("/users/{id}", {
  params: { id: "123" },
});

// ❌ TypeScript error - id must be string
await client.get("/users/{id}", {
  params: { id: 123 },
});

Response Validation

Response data is automatically validated when received:

const result = await client.get("/users/{id}", {
  params: { id: "123" },
});

if (result.success) {
  // result.body is validated and typed
  console.log(result.body.name); // ✅ Type-safe
}

If the response doesn't match the expected schema, an error is returned in the result.