gut

Convert Golang structs to Typescript interfaces

Handle

• json tags, like omitempty and inline appropriately
• uuid.UUID & time.Time conversion
• type generation for arrays
• setting custom names for the generated typescript interfaces
• types which use generics (see examples/5-generic-struct)

Install

go get github.com/tompston/gut

Example

main.go

example.gen.ts

package main import ( "fmt" "time" "github.com/google/uuid" "github.com/tompston/gut" ) func main() { // define which structs you want to convert ex1 := gut.Convert(User{}) ex2 := gut.Convert(Comments{}) ex3 := gut.Convert(MyRandomStruct{}) // concat all of the interfaces together interfaces := fmt.Sprintln(ex1, ex2, ex3) if err := gut.Generate("./example.gen.ts",interfaces); err != nil { fmt.Println(err) } } type User struct { ID uuid.UUID `json:"user_id"` Username string `json:"username"` CreatedAt time.Time `json:"created_at"` Comments `json:"comments,omitempty"` } type Comments []struct { ID int `json:"comment_id"` Value string `json:"value"` } type MyRandomStruct struct { MyFloat float64 MyInterface interface{} Ex1 map[string]map[string]string IntArray []int }

export type UuidType = string; export type BigIntType = BigInt; export type DateType = Date; export interface User { user_id: UuidType; username: string; created_at: DateType; comments?: { comment_id: number; value: string; }[]; } export type CommentsArray = Comments[]; export interface Comments { comment_id: number; value: string; } export interface MyRandomStruct { MyFloat: number; MyInterface: any; Ex1: { [key: string]: { [key: string]: string } }; IntArray: number[]; }

To format the generated typescript code, you can run deno fmt .

Why?

I wanted to solve the problem of converting golang structs to typescript interfaces, so that the backend and frontend clients could be in-sync, but I found that the current packages which try to do this had bugs and did not have the features I wanted. So I had to write it from scratch (with some help from ChatGPT)

Test

go test . -v -count=1

Features

• Handle cases when the convertable struct is an array

• Handle json ",omitempty" tags

• Handle json ",inline" tags (embeded structs)

  • If a struct has a field with an json ",inline" tag, then the generated typescript interface will have all of the fields from the embeded struct inside of it. (see examples/4-struct-with-inline)

• handle uuid.UUID & time.Time conversion

• Avoid duplicate interface names, by generating only one typescript interface which will hold all of the types that are present in the struct.

• Flexible typescript type system for the converted time.Time, uuid.UUID and int64 / uint64 types.

• optionally generate the type which holds an array of interfaces

• Ability to optionally rename the generated typescript interface to a custom name

• flexibility in exporting the converted go structs from packages

  • Convert() returns a string which holds the generated typescript interface, thus grouping the structs from multiple packages, concatenating them together and then saving them to a single file is quite trivial.

• Keep the package simple.

  • gut exports only 2 funtions
    • Convert() -> converts the struct into a ts string
    • Generate() -> save the converted ts interfaces to a file + define the settings for the types

Disclaimer

• The generated TS code is not formatted. Maybe I'll fix this later. The current way to format can be done by using deno fmt .
• There might be bugs.

Credits

The initial draft of the code was generated by ChatGPT. After some heavy refactoring, this is the end result.

Example 2 - Modify interface names + array types

main.go

example.gen.ts

package main import ( "fmt" "time" "github.com/google/uuid" "github.com/tompston/gut" ) func main() { // Insetad of generating an interface called User, // create one with a custom name ex1 := gut.Convert(User{}, gut.Type{Name: "MyCustomInterface"}) // Generate both the interface for the struct and // also a type which holds an array of interfaces. // + optionally you can also rename it. ex2 := gut.Convert(MyRandomStruct{}, gut.Type{IsArray: true, ArrayTypeName: "ArrayOfMyRandomStructs"}) // concat all of the interfaces together interfaces := fmt.Sprintln(ex1, ex2) if err := gut.Generate("./example.gen.ts", interfaces); err != nil { fmt.Println(err) } } type User struct { ID uuid.UUID `json:"user_id"` Username string `json:"username"` CreatedAt time.Time `json:"created_at"` Comments `json:"comments,omitempty"` } type Comments []struct { ID int `json:"comment_id"` Value string `json:"value"` } type MyRandomStruct struct { MyFloat float64 MyInterface interface{} Ex1 map[string]map[string]string `json:"ex_1"` IntArray []int `json:"int_array"` OptionalStringArray []string `json:"opt_str_array,omitempty"` }

export type UuidType = string; export type BigIntType = BigInt; export type DateType = Date; export interface MyCustomInterface { user_id: UuidType; username: string; created_at: DateType; comments?: { comment_id: number; value: string; }[]; } export type ArrayOfMyRandomStructs = MyRandomStruct[]; export interface MyRandomStruct { MyFloat: number; MyInterface: any; ex_1: { [key: string]: { [key: string]: string } }; int_array: number[]; opt_str_array?: string[]; }

Example 3 - Change the predefined typescript type values

main.go

example.gen.ts

package main import ( "fmt" "time" "github.com/google/uuid" "github.com/tompston/gut" ) func main() { // Insetad of generating an interface called User, // create one with a custom name ex1 := gut.Convert(User{}, gut.Type{Name: "MyCustomInterface"}) if err := gut.Generate( "./example.gen.ts", ex1, gut.Settings{ FirstLine: "// This is a custom comment in the file\n", DateType: "string", UuidType: "string", BigIntType: "number", }); err != nil { fmt.Println(err) } } type User struct { ID uuid.UUID `json:"user_id"` Username string `json:"username"` CreatedAt time.Time `json:"created_at"` }

// This is a custom comment in the file export type UuidType = string; export type BigIntType = number; export type DateType = string; export interface MyCustomInterface { user_id: UuidType; username: string; created_at: DateType; }