Fix deserialization of ID type

Deserialization of ID types caused an exception if the field was
nullable.

Author: hth313

src/FSharp.Data.GraphQL.Client/BaseTypes.fs

@@ -355,14 +355,16 @@ module internal JsonValueHelper =
                     | None -> failwith "Item type is a non null type, but no underlying type exists on the schema definition of the type."
                 | TypeKind.SCALAR ->
                     match schemaField.SchemaTypeRef.Name with
+                    | Some "String" | Some "ID" ->
+                        s |> makeSomeIfNeeded
                     | Some "URI" ->
-                        System.Uri(s) |> makeSomeIfNeeded
+                        s |> System.Uri |> makeSomeIfNeeded
                     | Some "Date" ->
                         match DateTime.TryParse(s, CultureInfo.InvariantCulture, DateTimeStyles.None) with
                         | (true, d) -> makeSomeIfNeeded d
                         | _ -> failwith "A string was received in the query response, and the schema recognizes it as a date and time sring, but the conversion failed."
                     | Some _ ->
-                        makeSomeIfNeeded s
+                        s |> makeSomeIfNeeded
                     | _ -> failwith "A string type was received in the query response item, but the matching schema field is not a string based type."
                 | TypeKind.ENUM when schemaField.SchemaTypeRef.Name.IsSome -> EnumBase(schemaField.SchemaTypeRef.Name.Value, s) |> makeSomeIfNeeded
                 | _ -> failwith "A string type was received in the query response item, but the matching schema field is not a string based type or an enum type."

tests/FSharp.Data.GraphQL.Tests/FSharp.Data.GraphQL.Tests.fsproj

@@ -54,6 +54,7 @@
     <Compile Include="NameValueLookupTests.fs" />
     <Compile Include="SubscriptionTests.fs" />
     <Compile Include="AstExtensionsTests.fs" />
+    <Compile Include="ResponseJsonTests.fs" />
     <Compile Include="Program.fs" />
   </ItemGroup>
 
@@ -65,6 +66,13 @@
   <ItemGroup>
     <ProjectReference Include="..\..\src\FSharp.Data.GraphQL.Shared\FSharp.Data.GraphQL.Shared.fsproj" />
     <ProjectReference Include="..\..\src\FSharp.Data.GraphQL.Server\FSharp.Data.GraphQL.Server.fsproj" />
+    <ProjectReference Include="..\..\src\FSharp.Data.GraphQL.Client.DesignTime\FSharp.Data.GraphQL.Client.DesignTime.fsproj" />
     <ProjectReference Include="..\..\src\FSharp.Data.GraphQL.Server.Middleware\FSharp.Data.GraphQL.Server.Middleware.fsproj" />
   </ItemGroup>
-</Project>
+</Project>
+  <ItemGroup Condition="$(OS) == Unix">
+    <Content Include="xunit.runner.json" CopyToOutputDirectory="PreserveNewest" />
+  </ItemGroup>
+  <Import Project="..\..\netfx.props" />
+  <Import Project="..\..\.paket\Paket.Restore.targets" />
+</Project>

tests/FSharp.Data.GraphQL.Tests/ResponseJsonTests.fs

@@ -0,0 +1,73 @@
+module FSharp.Data.GraphQL.Tests.ResponseJsonTests
+
+open System
+open Xunit
+open Helpers
+open FSharp.Data.GraphQL
+open FSharp.Data.GraphQL.Client
+
+// Local provider should be able to be created from local introspection json file.
+// This schema is adjusted to have some less common type names in order to test them.
+type Provider = GraphQLProvider<"introspection-altered-types.json">
+
+
+[<Fact>]
+let ``Should be able to parse nullable ID``() =
+    let op = Provider.Operation<"""query TestQuery {
+      hero(id:"1000") {
+          id,
+          name,
+          appearsIn,
+          homePlanet,
+          friends {
+            ... on Human {
+              name,
+              id
+            }
+            ... on Droid {
+              name,
+              id
+            }
+          }
+        }
+      }""">
+    let xop = op()
+    let result1 = xop.ParseResult("""{
+       "documentId": 2018203290,
+       "data": {
+         "hero": {
+          "id": "1000",
+          "__typename": "Human",
+          "name": "Luke Skywalker",
+          "appearsIn": [
+            "NewHope",
+            "Empire",
+            "Jedi"
+          ],
+          "homePlanet": "Tatooine",
+          "friends": [
+            {
+              "name": "Han Solo",
+              "id": "1002",
+              "__typename": "Human"
+            },
+            {
+              "name": "Leia Organa",
+              "id": "1003",
+              "__typename": "Human"
+            },
+            {
+              "name": "C-3PO",
+              "id": "2000",
+              "__typename": "Droid"
+            },
+            {
+              "name": "R2-D2",
+              "id": "2001",
+              "__typename": "Droid"
+            }
+          ]
+        }
+       }
+    }""")
+    ()