added '[package.metadata.github-api].set-headers' section in Cargo.to…

…ml with an array of http headers necessary to add in lib.rs/`build_request()` (created in build.rs; imported with include!)

Cargo.toml

@@ -14,6 +14,9 @@ categories = ["web-programming::http-client"]
 keywords = ["github", "github-api"]
 rust-version = "1.73.0"
 
+[package.metadata.github-api]
+set-headers = ["X-GitHub-Api-Version: 2022-11-28", ]
+
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 [package.metadata.docs.rs]
 all-features = true
@@ -74,6 +77,9 @@ base64 = "0.22.0"
 pretty_assertions = "1.4.0"
 graphql_client = "0.14.0"
 
+[build-dependencies]
+cargo_metadata = "0.23.0"
+
 [features]
 default = [
     "follow-redirect",

build.rs

@@ -0,0 +1,43 @@
+use cargo_metadata::MetadataCommand;
+use std::env;
+use std::fs;
+use std::path::Path;
+
+fn main() {
+    println!("cargo:rerun-if-changed=Cargo.toml");
+
+    let manifest_dir = env::var("CARGO_MANIFEST_DIR").unwrap(); // Cargo.toml path
+    let manifest_path = Path::new(&manifest_dir).join("Cargo.toml");
+
+    let metadata = MetadataCommand::new()
+        .manifest_path(&manifest_path)
+        .exec()
+        .expect("failed to parse `cargo metadata`");
+
+    let root_package = metadata.root_package().unwrap();
+    let custom_metadata = &root_package.metadata;
+
+    let set_headers_array = custom_metadata["github-api"]["set-headers"]
+        .as_array()
+        .cloned()
+        .unwrap_or(Default::default());
+    let set_headers_array = set_headers_array
+        .iter()
+        .map(|x| x.as_str().unwrap_or_default())
+        .map(|x| {
+            // split either by ":" or by ": "
+            x.split_once(": ")
+                .unwrap_or_else(|| (x.split_once(":")).unwrap_or_default())
+        })
+        .collect::<Vec<(&str, &str)>>();
+    let array_creation_static = format!(
+        "pub const _SET_HEADERS_MAP: [(&str, &str); {}] = {:?};",
+        &set_headers_array.len(),
+        &set_headers_array
+    );
+
+    let out_dir = env::var("OUT_DIR").unwrap(); // build's OUT path
+    let dest_path = Path::new(&out_dir).join("headers_metadata.rs");
+    fs::write(&dest_path, array_creation_static)
+        .expect(format!("failed to write {}", dest_path.display()).as_str());
+}

src/lib.rs

@@ -300,6 +300,15 @@ pub type Result<T, E = error::Error> = std::result::Result<T, E>;
 const GITHUB_BASE_URI: &str = "https://api.github.com";
 const GITHUB_BASE_UPLOAD_URI: &str = "https://uploads.github.com";
 
+/// This `include!` gives us pub const _SET_HEADERS_MAP: [(&str, &str)]
+/// generated from Cargo.toml `[package.metadata.github-api].set-headers` array, like
+/// ```
+/// [package.metadata.github-api]
+///
+/// set-headers = ["X-GitHub-Api-Version: 2022-11-28", ]
+/// ```
+include!(concat!(env!("OUT_DIR"), "/headers_metadata.rs"));
+
 #[cfg(feature = "default-client")]
 static STATIC_INSTANCE: Lazy<arc_swap::ArcSwap<Octocrab>> =
     Lazy::new(|| arc_swap::ArcSwap::from_pointee(Octocrab::default()));
@@ -1569,6 +1578,12 @@ impl Octocrab {
         // In case octocrab needs to support cases where body is strictly streamable, it should use something like reqwest::Body,
         // since it differentiates between retryable bodies, and streams(aka, it implements try_clone(), which is needed for middlewares like retry).
 
+        /// Add headers specified in Cargo.toml
+        /// '[package.metadata.github-api].set-headers' section
+        for kv in _SET_HEADERS_MAP {
+            builder = builder.header(kv.0, kv.1);
+        }
+
         if let Some(body) = body {
             builder = builder.header(http::header::CONTENT_TYPE, "application/json");
             let serialized = serde_json::to_string(body).context(SerdeSnafu)?;