Hi John,
Thank you for your reply. I am pleased that the solution is as simple as
you describe. The use of nullable types in the generated code is a big
bonus as well. I was not liking having to code against the raw
WellKnownType values!
David Razzetti
On Wednesday, October 25, 2017 at 7:42:41 AM UTC+1, Jon Skeet wrote:
>
> Okay, there are two pieces of good news:
>
> - I've managed to reproduce the issue
> - It's easy for you to fix by changing your proto and how you build
>
> Basically, you're not importing the wrapper types as in the way protoc
> expects.
>
> Instead of importing "wrappers.proto" and using -I on the command line to
> point to google/protobuf, you should import
> "google/protobuf/wrappers.proto" and use -I to point to the directory above
> google (in the protobuf tools package, which is where I assuming you're
> finding wrappers.proto) You can then refer to just "Int32Value" instead of
> ".google.protobuf.Int32Value", although the latter still works too.
>
> At that point, your NullableInt property should be generated as a .NET
> Nullable<int> rather than as an Int32Value, so you need to change your code
> to:
>
> var foo = new Foo { NullableInt = 5 }
>
>
> It should be much easier to work with at that point, aside from anything
> else.
>
> It turns out you're not the first person to run into this:
>
> - https://github.com/google/protobuf/issues/2574
> - https://github.com/google/protobuf/issues/2575
>
> ... but it's still not clear to me whether we *should* try to fully
> support the way you were generating the code before; it's entirely possible
> that other parts of protobuf infrastructure will be confused by this too. I
> can look at fixing this particular part of the C# codegen, but I wouldn't
> like to say it'll be plain sailing for everything else.
>
> Jon
>
>
> On 24 October 2017 at 21:56, Adam Cozzette <[email protected]
> <javascript:>> wrote:
>
>> +Jon Skeet, who is the expert on C# protos
>>
>> On Mon, Oct 16, 2017 at 7:41 AM, <[email protected]
>> <javascript:>> wrote:
>>
>>> Using Google.Protobuf Nuget package version 3.4.1
>>>
>>> In its simplest form, I have a Google protocol-buffers message defined
>>> like this:
>>>
>>> syntax = "proto3";package tests;
>>> option csharp_namespace = "MyTests";
>>> import "wrappers.proto";
>>>
>>> message Foo {
>>> .google.protobuf.Int32Value NullableInt = 1;}
>>>
>>> I compile it to C# code using Google's protoc tool from
>>> Google.Protobuf.Tools version 3.4.0.
>>>
>>> When I instantiate an instance of Foo and serialize it to a string using
>>> the Google.Protobuf.JsonFormatter I get a sensible result, which is "{
>>> "NullableInt": 5 }". When I de-serialize this back into a Foo instance
>>> using Google.Protobuf.JsonParser, the parser throws a
>>> System.InvalidCastException stating "Unable to cast object of type
>>> 'System.Int32' to type 'Google.Protobuf.WellKnownTypes.Int32Value'."
>>>
>>> Why is this exception being thrown? Am I doing something stupid?
>>>
>>> Here is the code that I am running:
>>>
>>> [Test]public void TestRoundTripInt32Value(){
>>> var foramtter = new JsonFormatter(new JsonFormatter.Settings(false));
>>> var foo = new Foo { NullableInt = new Int32Value {Value = 5} };
>>> var str = foramtter.Format(foo);
>>> Console.WriteLine(str);
>>> var parser = new JsonParser(new JsonParser.Settings(100));
>>> var foo2 = parser.Parse<Foo>(str); // <= Throws!
>>> Assert.That(foo2, Is.EqualTo(foo));}
>>>
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>>
>>
>
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