What is the correct way to make a custom .NET Exception serializable? -

-

more specifically, when exception contains custom objects may or may not serializable.

take example:

public class myexception : exception {     private readonly string resourcename;     private readonly ilist<string> validationerrors;      public myexception(string resourcename, ilist<string> validationerrors)     {         this.resourcename = resourcename;         this.validationerrors = validationerrors;     }      public string resourcename     {         { return this.resourcename; }     }      public ilist<string> validationerrors     {         { return this.validationerrors; }     } }

if exception serialized , de-serialized, 2 custom properties (resourcename , validationerrors) not preserved. properties return null.

is there common code pattern implementing serialization custom exception?

base implementation, without custom properties

serializableexceptionwithoutcustomproperties.cs:

namespace serializableexceptions {     using system;     using system.runtime.serialization;      [serializable]     // important: attribute not inherited exception, , must specified      // otherwise serialization fail serializationexception stating     // "type x in assembly y not marked serializable."     public class serializableexceptionwithoutcustomproperties : exception     {         public serializableexceptionwithoutcustomproperties()         {         }          public serializableexceptionwithoutcustomproperties(string message)              : base(message)         {         }          public serializableexceptionwithoutcustomproperties(string message, exception innerexception)              : base(message, innerexception)         {         }          // without constructor, deserialization fail         protected serializableexceptionwithoutcustomproperties(serializationinfo info, streamingcontext context)              : base(info, context)         {         }     } }

full implementation, custom properties

complete implementation of custom serializable exception (myserializableexception), , derived sealed exception (myderivedserializableexception).

the main points implementation summarized here:

  1. you must decorate each derived class [serializable] attribute — attribute not inherited base class, , if not specified, serialization fail serializationexception stating "type x in assembly y not marked serializable."
  2. you must implement custom serialization. [serializable] attribute alone not enough — exception implements iserializable means derived classes must implement custom serialization. involves 2 steps:
    1. provide serialization constructor. constructor should private if class sealed, otherwise should protected allow access derived classes.
    2. override getobjectdata() , make sure call through base.getobjectdata(info, context) @ end, in order let base class save own state.

serializableexceptionwithcustomproperties.cs:

namespace serializableexceptions {     using system;     using system.collections.generic;     using system.runtime.serialization;     using system.security.permissions;      [serializable]     // important: attribute not inherited exception, , must specified      // otherwise serialization fail serializationexception stating     // "type x in assembly y not marked serializable."     public class serializableexceptionwithcustomproperties : exception     {         private readonly string resourcename;         private readonly ilist<string> validationerrors;          public serializableexceptionwithcustomproperties()         {         }          public serializableexceptionwithcustomproperties(string message)              : base(message)         {         }          public serializableexceptionwithcustomproperties(string message, exception innerexception)             : base(message, innerexception)         {         }          public serializableexceptionwithcustomproperties(string message, string resourcename, ilist<string> validationerrors)             : base(message)         {             this.resourcename = resourcename;             this.validationerrors = validationerrors;         }          public serializableexceptionwithcustomproperties(string message, string resourcename, ilist<string> validationerrors, exception innerexception)             : base(message, innerexception)         {             this.resourcename = resourcename;             this.validationerrors = validationerrors;         }          [securitypermissionattribute(securityaction.demand, serializationformatter = true)]         // constructor should protected unsealed classes, private sealed classes.         // (the serializer invokes constructor through reflection, can private)         protected serializableexceptionwithcustomproperties(serializationinfo info, streamingcontext context)             : base(info, context)         {             this.resourcename = info.getstring("resourcename");             this.validationerrors = (ilist<string>)info.getvalue("validationerrors", typeof(ilist<string>));         }          public string resourcename         {             { return this.resourcename; }         }          public ilist<string> validationerrors         {             { return this.validationerrors; }         }          [securitypermissionattribute(securityaction.demand, serializationformatter = true)]         public override void getobjectdata(serializationinfo info, streamingcontext context)         {             if (info == null)             {                 throw new argumentnullexception("info");             }              info.addvalue("resourcename", this.resourcename);              // note: if "list<t>" isn't serializable may need work out             //       method of adding list, show...             info.addvalue("validationerrors", this.validationerrors, typeof(ilist<string>));              // must call through base class let save own state             base.getobjectdata(info, context);         }     } }

derivedserializableexceptionwithadditionalcustomproperties.cs:

namespace serializableexceptions {     using system;     using system.collections.generic;     using system.runtime.serialization;     using system.security.permissions;      [serializable]     public sealed class derivedserializableexceptionwithadditionalcustomproperty : serializableexceptionwithcustomproperties     {         private readonly string username;          public derivedserializableexceptionwithadditionalcustomproperty()         {         }          public derivedserializableexceptionwithadditionalcustomproperty(string message)             : base(message)         {         }          public derivedserializableexceptionwithadditionalcustomproperty(string message, exception innerexception)              : base(message, innerexception)         {         }          public derivedserializableexceptionwithadditionalcustomproperty(string message, string username, string resourcename, ilist<string> validationerrors)              : base(message, resourcename, validationerrors)         {             this.username = username;         }          public derivedserializableexceptionwithadditionalcustomproperty(string message, string username, string resourcename, ilist<string> validationerrors, exception innerexception)              : base(message, resourcename, validationerrors, innerexception)         {             this.username = username;         }          [securitypermissionattribute(securityaction.demand, serializationformatter = true)]         // serialization constructor private, class sealed         private derivedserializableexceptionwithadditionalcustomproperty(serializationinfo info, streamingcontext context)             : base(info, context)         {             this.username = info.getstring("username");         }          public string username         {             { return this.username; }         }          public override void getobjectdata(serializationinfo info, streamingcontext context)         {             if (info == null)             {                 throw new argumentnullexception("info");             }             info.addvalue("username", this.username);             base.getobjectdata(info, context);         }     } }

unit tests

mstest unit tests 3 exception types defined above.

unittests.cs:

namespace serializableexceptions {     using system;     using system.collections.generic;     using system.io;     using system.runtime.serialization.formatters.binary;     using microsoft.visualstudio.testtools.unittesting;      [testclass]     public class unittests     {         private const string message = "the widget has unavoidably blooped out.";         private const string resourcename = "resource-a";         private const string validationerror1 = "you forgot set whizz bang flag.";         private const string validationerror2 = "wally cannot operate in 0 gravity.";         private readonly list<string> validationerrors = new list<string>();         private const string username = "barry";          public unittests()         {             validationerrors.add(validationerror1);             validationerrors.add(validationerror2);         }          [testmethod]         public void testserializableexceptionwithoutcustomproperties()         {             exception ex =                 new serializableexceptionwithoutcustomproperties(                     "message", new exception("inner exception."));              // save full tostring() value, including exception message , stack trace.             string exceptiontostring = ex.tostring();              // round-trip exception: serialize , de-serialize binaryformatter             binaryformatter bf = new binaryformatter();             using (memorystream ms = new memorystream())             {                 // "save" object state                 bf.serialize(ms, ex);                  // re-use same stream de-serialization                 ms.seek(0, 0);                  // replace original exception de-serialized 1                 ex = (serializableexceptionwithoutcustomproperties)bf.deserialize(ms);             }              // double-check exception message , stack trace (owned base exception) preserved             assert.areequal(exceptiontostring, ex.tostring(), "ex.tostring()");         }          [testmethod]         public void testserializableexceptionwithcustomproperties()         {             serializableexceptionwithcustomproperties ex =                  new serializableexceptionwithcustomproperties(message, resourcename, validationerrors);              // sanity check: make sure custom properties set before serialization             assert.areequal(message, ex.message, "message");             assert.areequal(resourcename, ex.resourcename, "ex.resourcename");             assert.areequal(2, ex.validationerrors.count, "ex.validationerrors.count");             assert.areequal(validationerror1, ex.validationerrors[0], "ex.validationerrors[0]");             assert.areequal(validationerror2, ex.validationerrors[1], "ex.validationerrors[1]");              // save full tostring() value, including exception message , stack trace.             string exceptiontostring = ex.tostring();              // round-trip exception: serialize , de-serialize binaryformatter             binaryformatter bf = new binaryformatter();             using (memorystream ms = new memorystream())             {                 // "save" object state                 bf.serialize(ms, ex);                  // re-use same stream de-serialization                 ms.seek(0, 0);                  // replace original exception de-serialized 1                 ex = (serializableexceptionwithcustomproperties)bf.deserialize(ms);             }              // make sure custom properties preserved after serialization             assert.areequal(message, ex.message, "message");             assert.areequal(resourcename, ex.resourcename, "ex.resourcename");             assert.areequal(2, ex.validationerrors.count, "ex.validationerrors.count");             assert.areequal(validationerror1, ex.validationerrors[0], "ex.validationerrors[0]");             assert.areequal(validationerror2, ex.validationerrors[1], "ex.validationerrors[1]");              // double-check exception message , stack trace (owned base exception) preserved             assert.areequal(exceptiontostring, ex.tostring(), "ex.tostring()");         }          [testmethod]         public void testderivedserializableexceptionwithadditionalcustomproperty()         {             derivedserializableexceptionwithadditionalcustomproperty ex =                  new derivedserializableexceptionwithadditionalcustomproperty(message, username, resourcename, validationerrors);              // sanity check: make sure custom properties set before serialization             assert.areequal(message, ex.message, "message");             assert.areequal(resourcename, ex.resourcename, "ex.resourcename");             assert.areequal(2, ex.validationerrors.count, "ex.validationerrors.count");             assert.areequal(validationerror1, ex.validationerrors[0], "ex.validationerrors[0]");             assert.areequal(validationerror2, ex.validationerrors[1], "ex.validationerrors[1]");             assert.areequal(username, ex.username);              // save full tostring() value, including exception message , stack trace.             string exceptiontostring = ex.tostring();              // round-trip exception: serialize , de-serialize binaryformatter             binaryformatter bf = new binaryformatter();             using (memorystream ms = new memorystream())             {                 // "save" object state                 bf.serialize(ms, ex);                  // re-use same stream de-serialization                 ms.seek(0, 0);                  // replace original exception de-serialized 1                 ex = (derivedserializableexceptionwithadditionalcustomproperty)bf.deserialize(ms);             }              // make sure custom properties preserved after serialization             assert.areequal(message, ex.message, "message");             assert.areequal(resourcename, ex.resourcename, "ex.resourcename");             assert.areequal(2, ex.validationerrors.count, "ex.validationerrors.count");             assert.areequal(validationerror1, ex.validationerrors[0], "ex.validationerrors[0]");             assert.areequal(validationerror2, ex.validationerrors[1], "ex.validationerrors[1]");             assert.areequal(username, ex.username);              // double-check exception message , stack trace (owned base exception) preserved             assert.areequal(exceptiontostring, ex.tostring(), "ex.tostring()");         }     } }

Comments

Post a Comment

Popular posts from this blog

java - Custom OutputStreamAppender not run: LOGBACK: No context given for <MYAPPENDER> -

-
i wish write custom appender on basis of outputstreamappender . wrote following class package tests; import java.io.ioexception; import java.io.outputstream; import ch.qos.logback.core.outputstreamappender; public class myappender<e> extends outputstreamappender<e> { public myappender() { system.out.println("myappender created"); setoutputstream(new outputstream() { @override public void write(int b) throws ioexception { throw new unsupportedoperationexception(); } }); } } then wrote following runner: package tests; import org.slf4j.loggerfactory; import ch.qos.logback.classic.logger; public class runner { private static final logger log = (logger) loggerfactory.getlogger(runner.class); public static void main(string[] args) { //log.addappender(new myappender<iloggingevent>()); log.info("hello world"); } } finall...
Read more

java - UML - How would you draw a try catch in a sequence diagram? -

-
Image
is there standard way of drawing try catch sequence diagrams? i've made attempt based on this feel end result doesn't feel right. code diagram based around: public static void save () { try { filehandle filehandle = gdx.files.external(file); filehandle.writestring(boolean.tostring(constantshandler.soundenabled)+"\n", false); (int = 0; < 5; i++) { filehandle.writestring(integer.tostring(constantshandler.highscores[i])+"\n", true); } } catch (throwable e) { } } my attempt note: know still need add loop. that's ok. fragments meant show conditional control flow in sequence diagram. superstructures puts limitations on use of fragments (see pp. 467 of ss2.1.1). should use critical region try part above. , option catch . however, keep telling can take quite freedom in using uml. it's language , such changes in life time. long reader ge...
Read more

c++ - No viable overloaded operator for references a map -

-
i trying use map can make tag names reference number. when try , use it, in code error (6 in total every time reference map): src/main.cpp:25:45: error: no viable overloaded operator[] type 'std::map<std::string, std::string>' const char* idcs = node.child_value(tagmap[3]); this code: #include "pugi/pugixml.hpp" #include <iostream> #include <string> #include <map> int main() { pugi::xml_document doca, docb; std::map<std::string, pugi::xml_node> mapa, mapb; std::map<std::string, std::string> tagmap {{"1", "data"}, {"2", "entry"}, {"3", "id"}, {"4", "content"}}; if (!doca.load_file("a.xml") || !docb.load_file("b.xml")) { std::cout << "can't find input files"; return 1; } (auto& node: doca.child(tagmap[1]).children(tagmap[2])) { co...
Read more