feat(postgrest): set header on a per call basis

Sources/PostgREST/PostgrestBuilder.swift

@@ -49,6 +49,15 @@ public class PostgrestBuilder: @unchecked Sendable {
     )
   }
 
+  /// Set a HTTP header for the request.
+  @discardableResult
+  public func setHeader(name: String, value: String) -> Self {
+    mutableState.withValue {
+      $0.request.headers.update(name: name, value: value)
+    }
+    return self
+  }
+
   /// Executes the request and returns a response of type Void.
   /// - Parameters:
   ///   - options: Options for querying Supabase.

Tests/PostgRESTTests/PostgrestBuilderTests.swift

@@ -0,0 +1,23 @@
+//
+//  PostgrestBuilderTests.swift
+//  Supabase
+//
+//  Created by Guilherme Souza on 20/08/24.
+//
+
+@testable import PostgREST
+import XCTest
+
+final class PostgrestBuilderTests: XCTestCase {
+  let url = URL(string: "http://localhost:54321/rest/v1")!
+
+  func testCustomHeaderOnAPerCallBasis() throws {
+    let postgrest1 = PostgrestClient(url: url, headers: ["apikey": "foo"], logger: nil)
+    let postgrest2 = try postgrest1.rpc("void_func").setHeader(name: "apikey", value: "bar")
+
+    // Original client object isn't affected
+    XCTAssertEqual(postgrest1.from("users").select().mutableState.request.headers["apikey"], "foo")
+    // Derived client object uses new header value
+    XCTAssertEqual(postgrest2.mutableState.request.headers["apikey"], "bar")
+  }
+}