typescript-definitions
Exports serde-serializable structs and enums to Typescript definitions.
Motivation
Now that rust 2018 has landed there is no question that people should be using rust to write server applications (what are you thinking!). But currently generating wasm from rust code to run in the browser is too bleeding edge. Since javascript will be dominant on the client for the forseeable future there remains the problem of communicating with your javascript from your rust server.
Fundamental to this is to keep the datatypes on either side of the connection (http/websocket) in sync.
Typescript is an incremental typing system for javascript that is as tricked as rust (almost!) so why not create a typescript definition library based on your rust code?
Please see Credits.
example:
extern crate serde_derive;
extern crate typescript_definitions;
extern crate wasm_bindgen;
use*;
use Serialize;
use TypescriptDefinition;
With wasm-bindgen this will output in your .d.ts
definition file:
export type Enum =
{tag: "V1", fields: { Foo: boolean } }
| {tag: "V2", fields: { Bar: number, Baz: number } }
| {tag: "V3", fields: { Quux: string } }
;
Using typescript-definitions
In your crate create a lib target in Cargo.toml
pointing
to your "interfaces"
[]
= "mywasm" # whatever... you decide
= "src/interface.rs"
= ["cdylib"]
[]
=version="0.1.0"
= "0.2"
= "1"
= "1"
Then you can run
If you don't have these tools then see here:
or use wasm-pack (the typescript library will be in pkg/mywasm.d.ts
)
|
Using type_script_ify
You can ignore WASM totally and derive using TypeScriptify
as long as you have the following Trait
in scope:
// interface.rs
extern crate serde_derive;
extern crate typescript_definitions;
// wasm_bindgen not needed
// use::wasm_bindgen::prelude::*;
use Serialize;
use TypeScriptify;
// *you* have to provide this Trait because, currently, rust proc-macro crates can't
// export any public Traits etc... sorry about that.
Then in main.rs
(say) you can generate your own typescript specification using Struct::type_script_ify()
:
// need to pull in trait
use TypeScriptifyTrait;
Serde Internally or Adjacently tagged Enums
See Serde Docs.
This crate understands #[serde(tag="type")]
and #[serde(tag="tag", content="fields")]
attributes but only for Struct variants.
It doesn't do Untagged or Externally tagged enums but defaults
to #[serde(tag="kind")]
(Internal).
The default for NewTypes and Tuple types is
#[serde(tag="kind", content="fields")]
(Adjacent).
Problems
Currently typescript-descriptions
will not fail (AFAIK) even for
structs and enums with function types Fn(A,B) -> C
(generates C
). These make no sense in the current
context (data types, json serialization) so this might be considered a bug.
Watchout!
This might change if use cases show that an error would be better.
Two of the more common Enums are translated differently from Tagged types
Option<T>
=>T | null
Result<T,E>
=>T | E
instead of {tag:'T', ...} | {tag:'E', ...}
Deeply nested types might not translate correctly since currenly no attention it taken
with precedence of the '|' separator. For example it is possible
that Result<Option<T>,E>
will become T|null|E
instead of (T|null)|E
. But this
flattening seems better for typescript.
If you reference another type in a struct e.g.
then this will "work" (producing export type A = { x: number ,b: B<number> })
) but B will be opaque to
javascript unless B is also #[derive(TypescriptDefinition)]
.
Currently there is no help for this.
Formatting is rubbish and won't pass tslint. This is due to the quote! crate taking control of the output token stream. I don't know what it does with whitespace for example... (is whitespace a token in rust?).
Possibly add token guards ___put_newline_here___
at points where I want a newline and then stripping them out
with a regex after the stream is turned into a string.
We are not as clever as serde in determining the actual type. For example this won't "work":
use Cow as Pig;
gives export type S = { pig : Pig<string> }
instead of export type S = { pig : string }
We can't reasonably obey serde attributes like "flatten" since we would need to find the actual Struct object (from somewhere) and query its fields.
Credits
see http://timryan.org/2019/01/22/exporting-serde-types-to-typescript.html
Forked from wasm-typescript-definition
by @tcr
which was forked from rust-serde-schema
by @srijs.
type_script_ify
idea from typescriptify
by @n3phtys
Probably some others...
License
MIT or Apache-2.0, at your option.