Address review: add JsonSerializerOptions to context/request, use JsonSerializer.Serialize for variables

Agent-Logs-Url: https://github.com/fsprojects/FSharp.Data.GraphQL/sessions/63700bd7-a033-4fb4-a394-21e09ca3943e

Co-authored-by: xperiandri <2365592+xperiandri@users.noreply.github.com>

Author: Copilot

src/FSharp.Data.GraphQL.Client.DesignTime/ProvidedTypesHelper.fs

@@ -8,6 +8,7 @@ open System.Collections
 open System.Collections.Generic
 open System.Net.Http
 open System.Reflection
+open System.Text.Json
 open System.Text.Json.Serialization
 open FSharp.Core
 open FSharp.Data.GraphQL
@@ -333,7 +334,7 @@ module internal ProvidedOperation =
                     let serverUrl = info.ServerUrl
                     let headerNames = info.HttpHeaders |> Seq.map fst |> Array.ofSeq
                     let headerValues = info.HttpHeaders |> Seq.map snd |> Array.ofSeq
-                    <@@ { ServerUrl = serverUrl; HttpHeaders = Array.zip headerNames headerValues; Connection = new GraphQLClientConnection() } @@>
+                    <@@ { ServerUrl = serverUrl; HttpHeaders = Array.zip headerNames headerValues; Connection = new GraphQLClientConnection(); JsonSerializerOptions = Serialization.defaultSerializerOptions.Value } @@>
                 | None -> <@@ Unchecked.defaultof<GraphQLProviderRuntimeContext> @@>
             // We need to use the combination strategy to generate overloads for variables in the Run/AsyncRun methods.
             // The strategy follows the same principle with ProvidedRecord constructor overloads,
@@ -403,7 +404,8 @@ module internal ProvidedOperation =
                                   HttpHeaders = context.HttpHeaders
                                   OperationName = Option.ofObj operationName
                                   Query = actualQuery
-                                  Variables = %%variables }
+                                  Variables = %%variables
+                                  JsonSerializerOptions = context.JsonSerializerOptions }
                             let response =
                                 if shouldUseMultipartRequest
                                 then Tracer.runAndMeasureExecutionTime "Ran a multipart GraphQL query request" (fun _ -> GraphQLClient.sendMultipartRequest context.Connection request)
@@ -448,7 +450,8 @@ module internal ProvidedOperation =
                                   HttpHeaders = context.HttpHeaders
                                   OperationName = Option.ofObj operationName
                                   Query = actualQuery
-                                  Variables = %%variables }
+                                  Variables = %%variables
+                                  JsonSerializerOptions = context.JsonSerializerOptions }
                             async {
                                 let! ct = Async.CancellationToken
                                 let! response =
@@ -751,7 +754,8 @@ module internal Provider =
                                     | _ -> ProvidedParameter("serverUrl", typeof<string>)
                                 let httpHeaders = ProvidedParameter("httpHeaders", typeof<seq<string * string>>, optionalValue = null)
                                 let connectionFactory = ProvidedParameter("connectionFactory", typeof<unit -> GraphQLClientConnection>, optionalValue = null)
-                                [serverUrl; httpHeaders; connectionFactory]
+                                let jsonSerializerOptions = ProvidedParameter("jsonSerializerOptions", typeof<JsonSerializerOptions>, optionalValue = null)
+                                [serverUrl; httpHeaders; connectionFactory; jsonSerializerOptions]
                             let defaultHttpHeadersExpr =
                                 let names = httpHeaders |> Seq.map fst |> Array.ofSeq
                                 let values = httpHeaders |> Seq.map snd |> Array.ofSeq
@@ -766,7 +770,11 @@ module internal Provider =
                                         match %%args.[2] : unit -> GraphQLClientConnection with
                                         | argHeaders when obj.Equals(argHeaders, null) -> fun () -> new GraphQLClientConnection()
                                         | argHeaders -> argHeaders
-                                    { ServerUrl = %%serverUrl; HttpHeaders = httpHeaders; Connection = connectionFactory() } @@>
+                                    let jsonOptions =
+                                        match %%args.[3] : JsonSerializerOptions with
+                                        | null -> Serialization.defaultSerializerOptions.Value
+                                        | opts -> opts
+                                    { ServerUrl = %%serverUrl; HttpHeaders = httpHeaders; Connection = connectionFactory(); JsonSerializerOptions = jsonOptions } @@>
                             ProvidedMethod("GetContext", methodParameters, typeof<GraphQLProviderRuntimeContext>, invoker, isStatic = true)
                         let operationMethodDef =
                             let staticParams =

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

@@ -636,6 +636,7 @@ module VariableMapping =
         | :? string -> value
         | :? EnumBase as v -> v.GetValue () |> box
         | :? RecordBase as v -> v.ToDictionary () |> box
-        | OptionValue v -> v |> Option.map mapVariableValue |> box
+        | OptionValue None -> null
+        | OptionValue (Some v) -> mapVariableValue v
         | EnumerableValue v -> v |> Array.map mapVariableValue |> box
         | v -> v

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

@@ -7,6 +7,7 @@ open System
 open System.Collections.Generic
 open System.Net.Http
 open System.Text
+open System.Text.Json
 open System.Threading
 open System.Threading.Tasks
 
@@ -26,6 +27,8 @@ type GraphQLRequest = {
     Query : string
     /// Gets variables to be sent with the query.
     Variables : (string * obj)[]
+    /// Gets the JSON serializer options used for serializing request variables.
+    JsonSerializerOptions : JsonSerializerOptions
 }
 
 /// Executes calls to GraphQL servers and return their responses.
@@ -56,7 +59,7 @@ module GraphQLClient =
     /// Sends a request to a GraphQL server asynchronously.
     let sendRequestAsync ct (connection : GraphQLClientConnection) (request : GraphQLRequest) = task {
         let invoker = connection.Invoker
-        let json = Serialization.buildRequestJson request.OperationName request.Query request.Variables
+        let json = Serialization.buildRequestJson request.JsonSerializerOptions request.OperationName request.Query request.Variables
         let content = new StringContent (json, Encoding.UTF8, "application/json")
         return! postAsync ct invoker request.ServerUrl request.HttpHeaders content
     }
@@ -88,6 +91,7 @@ module GraphQLClient =
                     OperationName = None
                     Query = IntrospectionQuery.Definition
                     Variables = [||]
+                    JsonSerializerOptions = Serialization.defaultSerializerOptions.Value
                 }
                 try
                     return! sendRequestAsync ct connection request
@@ -130,7 +134,7 @@ module GraphQLClient =
             |> Array.collect (tryMapFileVariable >> (Option.defaultValue [||]))
 
         let operationContent =
-            let json = Serialization.buildRequestJson request.OperationName request.Query request.Variables
+            let json = Serialization.buildRequestJson request.JsonSerializerOptions request.OperationName request.Query request.Variables
             let content = new StringContent (json)
             content.Headers.Add ("Content-Disposition", "form-data; name=\"operations\"")
             content

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

@@ -4,6 +4,7 @@
 namespace FSharp.Data.GraphQL
 
 open System
+open System.Text.Json
 
 /// Contains information about a GraphQLRuntimeContext.
 type GraphQLRuntimeContextInfo =
@@ -17,6 +18,9 @@ type GraphQLProviderRuntimeContext =
       /// Gets the HTTP headers used for calls to the server that this context refers to.
       HttpHeaders : seq<string * string>
       /// Gets the connection component used to make calls to the server.
-      Connection : GraphQLClientConnection }
+      Connection : GraphQLClientConnection
+      /// Gets the JSON serializer options used for serializing request variables and
+      /// deserializing scalar values. Pass a customized instance to support custom scalar types.
+      JsonSerializerOptions : JsonSerializerOptions }
     interface IDisposable with
         member x.Dispose() = (x.Connection :> IDisposable).Dispose()

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

@@ -6,7 +6,6 @@ namespace FSharp.Data.GraphQL.Client
 open System
 open System.Collections.Generic
 open System.IO
-open System.Reflection
 open System.Text
 open System.Text.Json
 open FSharp.Data.GraphQL
@@ -202,8 +201,24 @@ module private SchemaParser =
 
 module Serialization =
 
-    let private isoDateFormat = "yyyy-MM-dd"
-    let private isoDateTimeFormat = "O"
+    /// The default JSON serializer options used for request serialization when no custom options are provided.
+    let defaultSerializerOptions =
+        lazy (FSharp.Data.GraphQL.Shared.Json.getSerializerOptions Seq.empty)
+
+    /// Converts special types (Uri, Upload, etc.) that System.Text.Json cannot handle natively
+    /// into their JSON-serializable representations. Applied recursively to variable values.
+    /// Also normalizes dictionary keys to camelCase to match GraphQL field naming conventions.
+    let rec private normalizeForSerialization (value : obj) : obj =
+        match value with
+        | null -> null
+        | :? string -> value // Must come before EnumerableValue: string implements IEnumerable
+        | :? Uri as u -> box (u.ToString ())
+        | :? Upload as u -> box u.Name // File variables are written as the form-part name string
+        | :? IDictionary<string, obj> as d ->
+            // Apply FirstCharLower to keys: RecordBase.ToDictionary() uses PascalCase (FirstCharUpper) for property names
+            d |> Seq.map (fun kvp -> kvp.Key.FirstCharLower (), normalizeForSerialization kvp.Value) |> dict |> box
+        | EnumerableValue items -> items |> Array.map normalizeForSerialization |> box
+        | v -> v
 
     /// Converts a JsonElement to an F# object recursively.
     let rec private deserializeElement (element : JsonElement) : obj =
@@ -236,55 +251,11 @@ module Serialization =
             |> Array.map (fun (name, element) -> name, deserializeElement element)
             |> Map.ofArray)
 
-    let private writeValue (writer : Utf8JsonWriter) =
-        let rec write (value : obj) =
-            match value with
-            | null -> writer.WriteNullValue ()
-            | OptionValue None -> writer.WriteNullValue ()
-            | OptionValue (Some v) -> write v
-            | :? bool as b -> writer.WriteBooleanValue b
-            | :? int as n -> writer.WriteNumberValue n
-            | :? float as f -> writer.WriteNumberValue f
-            | :? decimal as d -> writer.WriteNumberValue d
-            | :? int64 as n -> writer.WriteNumberValue n
-            | :? uint64 as n -> writer.WriteNumberValue n
-            | :? int16 as n -> writer.WriteNumberValue (int n)
-            | :? uint16 as n -> writer.WriteNumberValue (uint32 n)
-            | :? byte as n -> writer.WriteNumberValue (uint32 n)
-            | :? sbyte as n -> writer.WriteNumberValue (int n)
-            | :? string as s -> writer.WriteStringValue s
-            | :? Guid as g -> writer.WriteStringValue (g.ToString ())
-            | :? DateTime as d when d.Date = d -> writer.WriteStringValue (d.ToString isoDateFormat)
-            | :? DateTime as d -> writer.WriteStringValue (d.ToString isoDateTimeFormat)
-            | :? DateTimeOffset as d -> writer.WriteStringValue (d.ToString isoDateTimeFormat)
-            | :? Uri as u -> writer.WriteStringValue (u.ToString ())
-            | :? Upload as u -> writer.WriteStringValue u.Name
-            | :? IDictionary<string, obj> as dict ->
-                writer.WriteStartObject ()
-                for kvp in dict do
-                    writer.WritePropertyName (kvp.Key.FirstCharLower ())
-                    write kvp.Value
-                writer.WriteEndObject ()
-            | EnumerableValue items ->
-                writer.WriteStartArray ()
-                Array.iter write items
-                writer.WriteEndArray ()
-            | EnumValue s -> writer.WriteStringValue s
-            | _ ->
-                let props = value.GetType().GetProperties (BindingFlags.Public ||| BindingFlags.Instance)
-                writer.WriteStartObject ()
-                for p in props do
-                    writer.WritePropertyName (p.Name.FirstCharLower ())
-                    write (p.GetValue value)
-                writer.WriteEndObject ()
-        write
-
     /// Builds the JSON body for a standard GraphQL request.
-    let buildRequestJson (operationName : string option) (query : string) (variables : (string * obj) []) =
+    let buildRequestJson (options : JsonSerializerOptions) (operationName : string option) (query : string) (variables : (string * obj) []) =
         Tracer.runAndMeasureExecutionTime "Built GraphQL request JSON" (fun _ ->
             use stream = new MemoryStream ()
             use writer = new Utf8JsonWriter (stream, JsonWriterOptions (Indented = false))
-            let write = writeValue writer
             writer.WriteStartObject ()
             writer.WritePropertyName "operationName"
             match operationName with
@@ -296,11 +267,8 @@ module Serialization =
             if variables = null || variables.Length = 0 then
                 writer.WriteNullValue ()
             else
-                writer.WriteStartObject ()
-                for (name, value) in variables do
-                    writer.WritePropertyName name
-                    write value
-                writer.WriteEndObject ()
+                let dict = variables |> Array.map (fun (k, v) -> k, normalizeForSerialization v) |> dict
+                JsonSerializer.Serialize (writer, dict, options)
             writer.WriteEndObject ()
             writer.Flush ()
             Encoding.UTF8.GetString (stream.ToArray ()))