Deserializing JSON with properties that differ in casing #109768
Description
Description
It appears there is a regression in STJ when one migrates from .NET 8 to .NET 9 when one wants to deserialize JSON where there are two properties that differ in casing (e.g. [JsonPropertyName("a")] and [JsonPropertyName("A")]).
Reproduction Steps
Put the following console app code in Program.cs and run it using dotnet run:
using System.Text.Json;
using System.Text.Json.Serialization;
internal class Program
{
private static void Main(string[] args)
{
JsonSerializerOptions options = new() {
PropertyNameCaseInsensitive = false,
};
var box = JsonSerializer.Deserialize<Box>("""{"a": "Texas", "A": "California"}""", options);
}
}
public class Box
{
[JsonPropertyName("a")]
public string From { get; set; }
[JsonPropertyName("A")]
public string To { get; set; }
[JsonConstructor]
public Box(string from, string to)
{
From = from;
To = to;
}
}Expected behavior
No exception should be thrown as in .NET 8.
Actual behavior
Unhandled exception. System.InvalidOperationException: Members 'A' and 'a' on type 'Box' cannot both bind with parameter 'to' in the deserialization constructor.
at System.Text.Json.ThrowHelper.ThrowInvalidOperationException_MultiplePropertiesBindToConstructorParameters(Type parentType, String parameterName, String firstMatchName, String secondMatchName)
at System.Text.Json.Serialization.Metadata.JsonTypeInfo.ConfigureConstructorParameters()
at System.Text.Json.Serialization.Metadata.JsonTypeInfo.Configure()
at System.Text.Json.Serialization.Metadata.JsonTypeInfo.<EnsureConfigured>g__ConfigureSynchronized|172_0()
at System.Text.Json.JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
at System.Text.Json.JsonSerializerOptions.GetTypeInfoForRootType(Type type, Boolean fallBackToNearestAncestorType)
at System.Text.Json.JsonSerializer.GetTypeInfo[T](JsonSerializerOptions options)
at System.Text.Json.JsonSerializer.Deserialize[TValue](String json, JsonSerializerOptions options)
at Program.Main(String[] args) in /Users/Net9StjBug/Program.cs:line 13
Regression?
Yes. This works well in .NET 8.
Known Workarounds
I couldn't find any.
Configuration
.NET 9 GA
The issue does not appear to be platform specific.
Other information
I'm not sure if this issue is related to #108790 or not. It's the most similar issue I could find.