supervillain's Introduction

Supervillain

Converts Go structs to Zod schemas.

Usage:

type Post struct {
    Title string
}
type User struct {
    Name   string
    Nickname *string // pointers become optional
    Age    int
    Height float64
    Tags []string
    Favourites []struct { // nested structs are kept inline
        Name string
    }
    Posts []Post // external structs are emitted as separate exports
}

StructToZodSchema(User{})

Outputs:

export const PostSchema = z.object({
  title: z.string(),
});
export type Post = z.infer<typeof PostSchema>;

export const UserSchema = z.object({
  name: z.string(),
  nickname: z.string().optional(),
  age: z.number(),
  height: z.number(),
  tags: z.string().array(),
  favourites: z
    .object({
      name: z.string(),
    })
    .array(),
  posts: PostSchema.array(),
});
export type User = z.infer<typeof UserSchema>;

Custom Types

You can pass type name mappings to custom conversion functions:

c := supervillain.NewConverter(map[string]supervillain.CustomFn{
    "github.com/shopspring/decimal.Decimal": func(c *supervillain.Converter, t reflect.Type, s, g string, i int) string {
        // Shopspring's decimal type serialises to a string.
        return "z.string()"
    },
})

c.Convert(User{
    Money decimal.Decimal
})

Outputs:

export const UserSchema = z.object({
  Money: z.string(),
})
export type User = z.infer<typeof UserSchema>

There are some custom types with tests in the "custom" directory.

The function signature for custom type handlers is:

func(c *supervillain.Converter, t reflect.Type, typeName, genericTypeName string, indentLevel int) string

You can use the Converter to process nested types. The genericTypeName is the name of the T in Generic[T] and the indent level is for passing to other converter APIs.

Caveats

Does not support self-referential types - should be a simple fix.
Sometimes outputs in the wrong order - it really needs an intermediate DAG to solve this.

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