Add docs for set support (#1111)

* Add docs for set support

* Update lists.md

* Update lists.md

Co-authored-by: Shane Myrick <[email protected]>

Author: smyrick

examples/server/spring-server/src/main/kotlin/com/expediagroup/graphql/examples/server/spring/hooks/CustomSchemaGeneratorHooks.kt

@@ -32,6 +32,7 @@ import java.math.BigDecimal
 import java.util.UUID
 import kotlin.reflect.KClass
 import kotlin.reflect.KType
+import kotlin.reflect.full.createType
 import kotlin.reflect.full.isSubclassOf
 
 /**
@@ -52,9 +53,10 @@ class CustomSchemaGeneratorHooks(override val wiringFactory: KotlinDirectiveWiri
      * Register Reactor Mono monad type.
      */
     override fun willResolveMonad(type: KType): KType = when (type.classifier) {
-        Mono::class -> type.arguments.firstOrNull()?.type
+        Mono::class -> type.arguments.first().type ?: type
+        Set::class -> List::class.createType(type.arguments)
         else -> type
-    } ?: type
+    }
 
     /**
      * Exclude the Spring bean factory interface

examples/server/spring-server/src/main/kotlin/com/expediagroup/graphql/examples/server/spring/query/SimpleQuery.kt

@@ -83,4 +83,6 @@ class SimpleQuery : Query {
         Selection.ONE -> "You chose the first one"
         Selection.TWO -> "You chose the second one"
     }
+
+    fun setList(): Set<String> = setOf("one", "one", "two")
 }

website/docs/schema-generator/writing-schemas/lists.md

@@ -4,11 +4,10 @@ title: Lists
 ---
 Both `kotlin.Array` and `kotlin.collections.List` are automatically mapped to the GraphQL `List` type (for unsupported
 use cases see below). Type arguments provided to Kotlin collections are used as the type arguments in the GraphQL `List`
-type. Kotlin specialized classes representing arrays of Java primitive types without boxing overhead (e.g. `IntArray`)
+type. Kotlin specialized classes (e.g. `IntArray`) representing arrays of Java primitive types without boxing overhead
 are also supported.
 
 ```kotlin
-
 class SimpleQuery {
     fun generateList(): List<Int> {
         // some logic here that generates list
@@ -22,19 +21,16 @@ class SimpleQuery {
         // some logic here that processes list
     }
 }
-
 ```
 
 The above Kotlin class would produce the following GraphQL schema:
 
 ```graphql
-
 type Query {
     generateList: [Int!]!
     doSomethingWithIntArray(ints: [Int!]!): String!
     doSomethingWithIntList(ints: [Int!]!): String!
 }
-
 ```
 
 ## Primitive Arrays
@@ -52,12 +48,22 @@ the `kotlin.Array` of objects the underlying type is automatically mapped to Gra
 | `kotlin.CharArray`    |
 | `kotlin.BooleanArray` |
 
-&gt; NOTE: Underlying GraphQL types of primitive arrays will be corresponding to the built-in scalar types or extended
+&gt; NOTE: The underlying GraphQL types of primitive arrays will be corresponding to the built-in scalar types or extended
 &gt; scalar types provided by `graphql-java`.
 
 ## Unsupported Collection Types
 
-Currently GraphQL spec only supports `Lists`. Therefore even though Java and Kotlin support number of other collection
+Currently, the GraphQL spec only supports `Lists`. Therefore, even though Java and Kotlin support number of other collection
 types, `graphql-kotlin-schema-generator` only explicitly supports `Lists` and primitive arrays. Other collection types
 such as `Sets` (see [#201](https://github.com/ExpediaGroup/graphql-kotlin/issues/201)) and arbitrary `Map` data
-structures are not supported.
+structures are not supported out of the box. While we do not reccomend using `Map` or `Set` in the schema,
+they are supported with the use of the schema hooks.
+
+```kotlin
+override fun willResolveMonad(type: KType): KType = when (type.classifier) {
+    Set::class -> List::class.createType(type.arguments)
+    else -> type
+}
+```
+
+See [Discussion #1110](https://github.com/ExpediaGroup/graphql-kotlin/discussions/1110) for more details.