Instruction file imported from davidystephenson/overpromise (.cursor/rules/20-zod-for-typescript-only.mdc). Copyright stays with the author.

description: ONLY use Zod for values TypeScript supports globs: */

Only define schemas for values that TypeScript can support

• Only use Zod schemas for types that TypeScript recognizes.
• NEVER use .min, .max, .email, .transform, .refine, .default.
• The purpose of using Zod is to make TypeScript safe.
• If you need to validate a non-TypeScript aspect of a value somewhere outside of Zod types files, don't modify any Zod schemas.
• Instead:

  • Use custom conditional logic

  • Use an if statment to check if the value is incorrect in that aspect

  • If it is, throw an error

  • Otherwise, continue with confidence that the aspect is safe.

  • For example:

    // Incorrect
    const passwordSchema = z.string().min(8)
    function handleSubmit (password: string) {
      const safe = passwordSchema.parse(password)
      submit(safe)
    }
    
    // Correct
    const passwordSchema = z.string()
    function handleSubmit (password: string() {
      const parsed = passworSchema.parse(password)
      if (parsed.length < 8) {
        throw new Error('The password must be at least 8 characters')
      }
      submit(safe)
    }