System.Text.Json source generator fails for covariant properties when [JsonIgnore] is specified #63443
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dotnet-issue-labeler
bot
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area-System.Text.Json
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Tagging subscribers to this area: @dotnet/area-system-text-json Issue DetailsDescriptionI have a class hierarchy where the derived class overrides one of the properties using covariant return type. I want to omit this property from the JSON, so I added [JsonIgnore] attributes to both properties: public class A
{
[JsonIgnore]
public virtual object Id { get; }
}
public class GenericB<T> : A
where T : class
{
[JsonIgnore]
public override T Id { get; }
}When I try to use the Json source generator for the derived type, it fails. I tried without generics, but it also fails. Reproduction StepsAdd the following classes to a .NET 6 project and try to build it: using System.Text.Json.Serialization;
public class A
{
[JsonIgnore]
public virtual object Id { get; }
}
public class B : A
{
[JsonIgnore]
public override string Id { get; }
}
public class GenericB<T> : A
where T : class
{
[JsonIgnore]
public override T Id { get; }
}
[JsonSerializable(typeof(B))]
[JsonSerializable(typeof(GenericB<string>))]
public partial class Context : JsonSerializerContext
{
}Expected behaviorThe project should build without errors. Actual behaviorThe source generator fails with an error: Regression?No response Known WorkaroundsNo response Configuration.NET 6.0.101 Other informationNo response
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Agreed this looks incorrect, any chance you'd be interested in contributing a fix? |
krwq
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bug
and removed
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Yes, I can take a look. |
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The exception is thrown at this line: runtime/src/libraries/System.Text.Json/gen/TypeGenerationSpec.cs Lines 223 to 226 in 5626066 Based on this, I tested a similar case and found that the generator runs into the same problem when there is no covariance involved, only property hiding without overriding: public class IgnoredBase
{
[JsonIgnore]
public string Id { get; set; }
}
public class IgnoredBase_IgnoredDerived : IgnoredBase
{
[JsonIgnore]
public new string Id { get; set; }
}Modifying the Add to TryAdd would solve this issue, but what about other cases when only one of the properties has the [JsonIgnore] attribute? public class IgnoredBase
{
[JsonIgnore]
public string Id { get; set; }
}
public class IgnoredBase_NotIgnoredDerived : IgnoredBase
{
public new string Id { get; set; }
}
public class NotIgnoredBase
{
public string Id { get; set; }
}
public class NotIgnoredBase_IgnoredDerived : NotIgnoredBase
{
[JsonIgnore]
public new string Id { get; set; }
}
NotIgnoredBase a = new NotIgnoredBase_IgnoredDerived();
a.Id = "Test"; // Should be serialized?
var b = new NotIgnoredBase_IgnoredDerived();
b.Id = "Test"; // Should be ignored?
IgnoredBase c = new IgnoredBase_NotIgnoredDerived();
c.Id = "Test"; // Should be ignored?
var d = new IgnoredBase_NotIgnoredDerived();
d.Id = "Test"; // Should be serialized? |
layomia
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the
source-generator
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Slightly related to #59364 which also tracks |
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More relevant, #50078 |
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As per #63823 (comment) we need to look at this problem holistically and write down all scenarios and their expected behavior before we start making any fixes |
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Fixed by #84756 |
ghost
locked as resolved and limited conversation to collaborators
Description
I have a class hierarchy where the derived class overrides one of the properties using covariant return type. I want to omit this property from the JSON, so I added [JsonIgnore] attributes to both properties:
When I try to use the Json source generator for the derived type, it fails. I tried without generics, but it also fails.
Reproduction Steps
Add the following classes to a .NET 6 project and try to build it:
Expected behavior
The project should build without errors.
Actual behavior
The source generator fails with an error:
Regression?
No response
Known Workarounds
No response
Configuration
.NET 6.0.101
Microsoft Windows [Version 10.0.19044.1415]
x64
Other information
No response
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