Not sure what your reaction will be if you receive an instance of a DTO from some method call where all properties/fields are default values like 0 or null, like the one below which i encountered today:

{
Applicant: null,ApplicantId: 0,AuditTime: null,AuthenticationId: 0,BackPhotoIdUrl: null,BrandName: null,Capital: null,CompanyFullName: null,CompanyId: 0,CompanyName: null,Corporation: null,CreatedTime: '0001-01-01T00:00:00+08:00',EstablishTime: null,IdCardNumber: null,LicenseNo: null,LicenseUrl: null,Mobile: null,Operator: null,PhotoIdUrl: null,Remark: null,Status: 0,StatusDisplayString: '未知', //this is the default value of an enum
}

I developed this c# extension is to help mitigate a particular problem while using protobuf-net.Grpc. The detailed problem is described in this issue: protobuf-net/protobuf-net.Grpc#36. In a word, it is basically because prototobuf does not have a concept of null. Grpc client will receive an object with default property values even if Grpc Server returns null.

Originally, I have a set of services which are invoked directly. Recently I am migrating them to RPC services using protobuf-net.Grpc. We used to return null to indicate something really is not there but now we get empty non-null objects like the one above which breaks a lot of existing code.

This extension will help you convert a non-null objects with all public properties/fields equal to their default values back to null. Of course you have to explicity call the extension method, but it is much easier than checking all props/fields manually yourself.

voidMain(){Func<object,string,string>p=(o,tag)=>JsonConvert.SerializeObject(o).Dump(tag);varp1=newPerson();varp2=newPerson{Name="Yuan Jian"};p(p1.NullifyIfAllDefault(),"p1");// nullp(p2.NullifyIfAllDefault(),"p2");// {"Age":0,"Name":"Yuan Jian","Spouse":null}objecto1=p1,o2=p2;p(o1.NullifyIfAllDefault(),"o1");// nullp(o2.NullifyIfAllDefault(),"o2");// {"Age":0,"Name":"Yuan Jian","Spouse":null}}publicclassPerson{publicintAge{get;set;}publicstringName{get;set;}publicPersonSpouse{get;set;}}