From 3e8b5c44d8f95eebb88bbab85d68f057235c878a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fredrik=20W=C3=A4rnsberg?= <fredrik@warnsberg.se>
Date: Mon, 15 Nov 2021 02:10:15 +0100
Subject: [PATCH] feat: Add @GQLExcluded (#1141)

* feat: Add @GQLExcluded

* PR Comments

* more _ :D
---
 .../caliban/schema/SchemaDerivation.scala     |  1 +
 .../caliban/schema/SchemaDerivation.scala     |  4 +++-
 .../scala/caliban/schema/Annotations.scala    |  5 +++++
 .../scala/caliban/schema/SchemaSpec.scala     | 21 ++++++++++++++++++-
 4 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/core/src/main/scala-2/caliban/schema/SchemaDerivation.scala b/core/src/main/scala-2/caliban/schema/SchemaDerivation.scala
index e865e16de7..da4ef31b99 100644
--- a/core/src/main/scala-2/caliban/schema/SchemaDerivation.scala
+++ b/core/src/main/scala-2/caliban/schema/SchemaDerivation.scala
@@ -64,6 +64,7 @@ trait SchemaDerivation[R] extends LowPriorityDerivedSchema {
           Some(getName(ctx)),
           getDescription(ctx),
           ctx.parameters
+            .filterNot(_.annotations.exists(_ == GQLExcluded()))
             .map(p =>
               __Field(
                 getName(p),
diff --git a/core/src/main/scala-3/caliban/schema/SchemaDerivation.scala b/core/src/main/scala-3/caliban/schema/SchemaDerivation.scala
index 51b1dfdc10..dfc44cbaf1 100644
--- a/core/src/main/scala-3/caliban/schema/SchemaDerivation.scala
+++ b/core/src/main/scala-3/caliban/schema/SchemaDerivation.scala
@@ -143,7 +143,9 @@ trait SchemaDerivation[R] {
               makeObject(
                 Some(getName(annotations, info)),
                 getDescription(annotations),
-                fields.map { case (label, _, schema, _) =>
+                fields.filterNot { case (label, _, _, _) =>
+                  paramAnnotations.getOrElse(label, Nil).exists(_ == GQLExcluded())
+                }.map { case (label, _, schema, _) =>
                   val fieldAnnotations = paramAnnotations.getOrElse(label, Nil)
                   __Field(
                     getName(fieldAnnotations, label),
diff --git a/core/src/main/scala/caliban/schema/Annotations.scala b/core/src/main/scala/caliban/schema/Annotations.scala
index ced4505e82..fd4c05aadc 100644
--- a/core/src/main/scala/caliban/schema/Annotations.scala
+++ b/core/src/main/scala/caliban/schema/Annotations.scala
@@ -16,6 +16,11 @@ object Annotations {
    */
   case class GQLDescription(value: String) extends StaticAnnotation
 
+  /**
+   * Annotation used to exclude a field from a type.
+   */
+  case class GQLExcluded() extends StaticAnnotation
+
   /**
    * Annotation used to customize the name of an input type.
    * This is usually needed to avoid a name clash when a type is used both as an input and an output.
diff --git a/core/src/test/scala/caliban/schema/SchemaSpec.scala b/core/src/test/scala/caliban/schema/SchemaSpec.scala
index a6739e00d1..88245898e4 100644
--- a/core/src/test/scala/caliban/schema/SchemaSpec.scala
+++ b/core/src/test/scala/caliban/schema/SchemaSpec.scala
@@ -1,8 +1,10 @@
 package caliban.schema
 
 import java.util.UUID
+import caliban.GraphQL.graphQL
+import caliban.RootResolver
 import caliban.introspection.adt.{ __DeprecatedArgs, __Type, __TypeKind }
-import caliban.schema.Annotations.{ GQLInterface, GQLUnion, GQLValueType }
+import caliban.schema.Annotations.{ GQLExcluded, GQLInterface, GQLUnion, GQLValueType }
 import zio.blocking.Blocking
 import zio.console.Console
 import zio.query.ZQuery
@@ -162,6 +164,23 @@ object SchemaSpec extends DefaultRunnableSpec {
         assert(introspect[Queries].fields(__DeprecatedArgs()).toList.flatten.headOption.map(_.`type`()))(
           isSome(hasField[__Type, Option[String]]("name", _.name, equalTo(Some("Wrapper"))))
         )
+      },
+      test("GQLExcluded") {
+        case class QueryType(a: String, @GQLExcluded b: String)
+        case class Query(query: QueryType)
+        val gql      = graphQL(RootResolver(Query(QueryType("a", "b"))))
+        val expected = """schema {
+                         |  query: Query
+                         |}
+
+                         |type Query {
+                         |  query: QueryType!
+                         |}
+
+                         |type QueryType {
+                         |  a: String!
+                         |}""".stripMargin
+        assertTrue(gql.render == expected)
       }
     )