Feat: add default export directory override (#195)

* feat: default export path
* added docs
* document why __private mod is pub
* add default env dir test to ci
* add export_to to crate1 dependency for tests

.github/workflows/test.yml

@@ -14,6 +14,11 @@ jobs:
         run: |
           cargo t 
           tsc bindings/* --noEmit
+      - name: dependencies e2e test with default export env
+        working-directory: e2e/dependencies/consumer
+        run: |
+          TS_RS_EXPORT_DIR=custom-bindings cargo t 
+          tsc custom-bindings/* --noEmit
   e2e-workspace:
     name: Run 'workspace' end-to-end test
     runs-on: ubuntu-latest
@@ -27,6 +32,11 @@ jobs:
         run: |
           cargo t 
           tsc parent/bindings/* --noEmit
+      - name: workspace e2e with default export env
+        working-directory: e2e/workspace
+        run: |
+          TS_RS_EXPORT_DIR=custom-bindings cargo t 
+          tsc parent/custom-bindings/* --noEmit
 
   readme-up-to-date:
     name: Check that README.md is up-to-date

e2e/workspace/crate1/src/lib.rs

@@ -1,6 +1,7 @@
 use ts_rs::TS;
 
 #[derive(TS)]
+#[ts(export_to = "crate1/")]
 pub struct Crate1 {
     pub x: [[[i32; 128]; 128]; 128],
-}
+}

macros/src/lib.rs

@@ -48,12 +48,18 @@ impl DerivedTS {
     }
 
     fn into_impl(self, rust_ty: Ident, generics: Generics) -> TokenStream {
+        let mut get_export_to = quote! {};
         let export_to = match &self.export_to {
             Some(dirname) if dirname.ends_with('/') => {
                 format!("{}{}.ts", dirname, self.name)
             }
             Some(filename) => filename.clone(),
             None => {
+                get_export_to = quote! {
+                    fn get_export_to() -> Option<String> {
+                        ts_rs::__private::get_export_to_path::<Self>()
+                    }
+                };
                 format!("bindings/{}.ts", self.name)
             }
         };
@@ -95,6 +101,8 @@ impl DerivedTS {
         quote! {
             #impl_start {
                 const EXPORT_TO: Option<&'static str> = Some(#export_to);
+                #get_export_to
+
                 #docs
 
                 fn decl() -> String {

ts-rs/src/export.rs

@@ -4,6 +4,7 @@ use std::{
     fmt::Write,
     path::{Component, Path, PathBuf},
     sync::Mutex,
+    sync::OnceLock,
 };
 
 use thiserror::Error;
@@ -128,6 +129,28 @@ pub(crate) fn export_type_to<T: TS + ?Sized + 'static, P: AsRef<Path>>(
     Ok(())
 }
 
+#[doc(hidden)]
+pub mod __private {
+    use super::*;
+
+    const EXPORT_DIR_ENV_VAR: &str = "TS_RS_EXPORT_DIR";
+    fn provided_default_dir() -> Option<&'static str> {
+        static EXPORT_TO: OnceLock<Option<String>> = OnceLock::new();
+        EXPORT_TO.get_or_init(|| std::env::var(EXPORT_DIR_ENV_VAR).ok()).as_deref()
+    }
+
+    /// Returns the path to where `T` should be exported using the `TS_RS_EXPORT_DIR` environment variable.
+    ///
+    /// This should only be used by the TS derive macro; the `get_export_to` trait method should not
+    /// be overridden if the `#[ts(export_to = ..)]` attribute exists.
+    pub fn get_export_to_path<T: TS + ?Sized>() -> Option<String> {
+        provided_default_dir().map_or_else(
+            || T::EXPORT_TO.map(ToString::to_string),
+            |path| Some(format!("{path}/{}.ts", T::name())),
+        )
+    }
+}
+
 /// Returns the generated defintion for `T`.
 pub(crate) fn export_type_to_string<T: TS + ?Sized + 'static>() -> Result<String, ExportError> {
     let mut buffer = String::with_capacity(1024);
@@ -141,7 +164,8 @@ pub(crate) fn export_type_to_string<T: TS + ?Sized + 'static>() -> Result<String
 fn output_path<T: TS + ?Sized>() -> Result<PathBuf, ExportError> {
     let manifest_dir = std::env::var("CARGO_MANIFEST_DIR").map_err(|_| ManifestDirNotSet)?;
     let manifest_dir = Path::new(&manifest_dir);
-    let path = PathBuf::from(T::EXPORT_TO.ok_or(CannotBeExported(std::any::type_name::<T>()))?);
+    let path =
+        PathBuf::from(T::get_export_to().ok_or(CannotBeExported(std::any::type_name::<T>()))?);
     Ok(manifest_dir.join(path))
 }
 
@@ -160,7 +184,8 @@ fn generate_decl<T: TS + ?Sized>(out: &mut String) {
 
 /// Push an import statement for all dependencies of `T`
 fn generate_imports<T: TS + ?Sized + 'static>(out: &mut String) -> Result<(), ExportError> {
-    let path = Path::new(T::EXPORT_TO.ok_or(CannotBeExported(std::any::type_name::<T>()))?);
+    let export_to = T::get_export_to().ok_or(CannotBeExported(std::any::type_name::<T>()))?;
+    let path = Path::new(&export_to);
 
     let deps = T::dependencies();
     let deduplicated_deps = deps
@@ -170,7 +195,7 @@ fn generate_imports<T: TS + ?Sized + 'static>(out: &mut String) -> Result<(), Ex
         .collect::<BTreeMap<_, _>>();
 
     for (_, dep) in deduplicated_deps {
-        let rel_path = import_path(path, Path::new(dep.exported_to));
+        let rel_path = import_path(path, Path::new(&dep.exported_to));
         writeln!(
             out,
             "import type {{ {} }} from {:?};",

ts-rs/src/lib.rs

@@ -171,6 +171,10 @@ pub use ts_rs_macros::TS;
 pub use crate::export::ExportError;
 use crate::typelist::TypeList;
 
+// Used in generated code. Not public API
+#[doc(hidden)]
+pub use crate::export::__private;
+
 #[cfg(feature = "chrono-impl")]
 mod chrono;
 mod export;
@@ -199,10 +203,18 @@ pub mod typelist;
 ///
 /// - `#[ts(export)]`:  
 ///   Generates a test which will export the type, by default to `bindings/<name>.ts` when running
-///   `cargo test`
+///   `cargo test`. The default base directory can be overridden with the `TS_RS_EXPORT_DIR` environment variable.
+///   Adding the variable to a project's [config.toml](https://doc.rust-lang.org/cargo/reference/config.html#env) can
+///   make it easier to manage.
+/// ```toml
+/// # <project-root>/.cargo/config.toml
+/// [env]
+/// TS_RS_EXPORT_DIR = { value = "<OVERRIDE_DIR>", relative = true }
+/// ```
 ///
 /// - `#[ts(export_to = "..")]`:  
 ///   Specifies where the type should be exported to. Defaults to `bindings/<name>.ts`.  
+///   The `export_to` attribute will also override the `TS_RS_EXPORT_DIR` environment variable.  
 ///   If the provided path ends in a trailing `/`, it is interpreted as a directory.   
 ///   Note that you need to add the `export` attribute as well, in order to generate a test which exports the type.
 ///
@@ -271,6 +283,10 @@ pub trait TS {
     const EXPORT_TO: Option<&'static str> = None;
     const DOCS: Option<&'static str> = None;
 
+    fn get_export_to() -> Option<String> {
+        Self::EXPORT_TO.map(ToString::to_string)
+    }
+
     /// Declaration of this type, e.g. `interface User { user_id: number, ... }`.
     /// This function will panic if the type has no declaration.
     fn decl() -> String {
@@ -370,15 +386,15 @@ pub struct Dependency {
     pub ts_name: String,
     /// Path to where the type would be exported. By default a filename is derived from the types
     /// name, which can be customized with `#[ts(export_to = "..")]`.
-    pub exported_to: &'static str,
+    pub exported_to: String,
 }
 
 impl Dependency {
     /// Constructs a [`Dependency`] from the given type `T`.
     /// If `T` is not exportable (meaning `T::EXPORT_TO` is `None`), this function will return
     /// `None`
     pub fn from_ty<T: TS + 'static + ?Sized>() -> Option<Self> {
-        let exported_to = T::EXPORT_TO?;
+        let exported_to = T::get_export_to()?;
         Some(Dependency {
             type_id: TypeId::of::<T>(),
             ts_name: T::name(),