feat(database): add select on query result (#275)

Sources/PostgREST/PostgrestTransformBuilder.swift

@@ -20,6 +20,12 @@ public class PostgrestTransformBuilder: PostgrestBuilder {
     .joined(separator: "")
     mutableState.withValue {
       $0.request.query.append(URLQueryItem(name: "select", value: cleanedColumns))
+
+      if $0.request.headers["Prefer"] != nil {
+        $0.request.headers["Prefer", default: ""] += ","
+      }
+
+      $0.request.headers["Prefer", default: ""] += "return=representation"
     }
     return self
   }

Tests/PostgRESTTests/BuildURLRequestTests.swift

@@ -162,6 +162,11 @@ final class BuildURLRequestTests: XCTestCase {
           .from("objects")
           .select()
       },
+      TestCase(name: "select after an insert") { client in
+        try await client.from("users")
+          .insert(User(email: "[email protected]"))
+          .select("id,email")
+      }
     ]
 
     for testCase in testCases {

Tests/PostgRESTTests/__Snapshots__/BuildURLRequestTests/testBuildRequest.select-after-an-insert.txt

@@ -0,0 +1,8 @@
+curl \
+	--request POST \
+	--header "Accept: application/json" \
+	--header "Content-Type: application/json" \
+	--header "Prefer: return=representation" \
+	--header "X-Client-Info: postgrest-swift/x.y.z" \
+	--data "{\"email\":\"[email protected]\"}" \
+	"https://example.supabase.co/users?select=id,email"