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How to handle this exception?In the following C# code, I tried to get the values for each property in an object: public void WriteObjectValue(object obj) { Type objectType = obj.GetType(); PropertyInfo[] properties = objectType.GetProperties(); foreach (PropertyInfo property in properties) { System.Object propertyValue = property.GetValue(obj, null); Console.WriteLine(propertyValue.ToString()); } } This worked fine, except in the following situation: If the passed object obj was defined like the follows Public class IntObjClass { int? deptId; int? sectionId; public int DeptId {set {deptId = value;}} public int SectioinId {set {sectionId = value;}} } and only sectionId was assigned a value, say 100, while deptId was left null. At this situation, the foreach loop will throw an exception at System.Object propertyValue = property.GetValue(), complaining deptId was null. Is there a way to get around this? (I don't want to use try{} catch {} to handle this exception) Thanks a lot for your help. Hello,
Have you tried this? if (propertyValue == null) { Console.WriteLine("<null>"); } else { Console.WriteLine(propertyValue.ToString()); } Best regards, Henning Krause Show quote "Andrew" <And***@discussions.microsoft.com> wrote in message news:28BFF904-952F-4194-8987-7C7D6D5DD246@microsoft.com... > Hello, friends, > > In the following C# code, I tried to get the values for each property in > an > object: > > public void WriteObjectValue(object obj) > { > Type objectType = obj.GetType(); > PropertyInfo[] properties = objectType.GetProperties(); > > foreach (PropertyInfo property in properties) > { > System.Object propertyValue = property.GetValue(obj, > null); > Console.WriteLine(propertyValue.ToString()); > } > } > > This worked fine, except in the following situation: > > If the passed object obj was defined like the follows > > Public class IntObjClass > { > int? deptId; > int? sectionId; > > public int DeptId {set {deptId = value;}} > public int SectioinId {set {sectionId = value;}} > > } > > and only sectionId was assigned a value, say 100, while deptId was left > null. > > At this situation, the foreach loop will throw an exception at > System.Object propertyValue = property.GetValue(), > complaining deptId was null. > > Is there a way to get around this? (I don't want to use try{} catch {} to > handle this exception) > > Thanks a lot for your help. It was the
propertyValue = property.GetValue(obj, null); throw the exception (Nullable object must have a value) before I had a chance to check if properValue was null or not. Any other ideas? Thanks. Show quote "Henning Krause [MVP - Exchange]" wrote: > Hello, > > Have you tried this? > > if (propertyValue == null) { > Console.WriteLine("<null>"); > } > else > { > Console.WriteLine(propertyValue.ToString()); > } > > Best regards, > Henning Krause > > "Andrew" <And***@discussions.microsoft.com> wrote in message > news:28BFF904-952F-4194-8987-7C7D6D5DD246@microsoft.com... > > Hello, friends, > > > > In the following C# code, I tried to get the values for each property in > > an > > object: > > > > public void WriteObjectValue(object obj) > > { > > Type objectType = obj.GetType(); > > PropertyInfo[] properties = objectType.GetProperties(); > > > > foreach (PropertyInfo property in properties) > > { > > System.Object propertyValue = property.GetValue(obj, > > null); > > Console.WriteLine(propertyValue.ToString()); > > } > > } > > > > This worked fine, except in the following situation: > > > > If the passed object obj was defined like the follows > > > > Public class IntObjClass > > { > > int? deptId; > > int? sectionId; > > > > public int DeptId {set {deptId = value;}} > > public int SectioinId {set {sectionId = value;}} > > > > } > > > > and only sectionId was assigned a value, say 100, while deptId was left > > null. > > > > At this situation, the foreach loop will throw an exception at > > System.Object propertyValue = property.GetValue(), > > complaining deptId was null. > > > > Is there a way to get around this? (I don't want to use try{} catch {} to > > handle this exception) > > > > Thanks a lot for your help. > > more like
if (property == null) { } else { } should work VJ Show quote "Andrew" <And***@discussions.microsoft.com> wrote in message news:200E4804-4C1E-4D2E-93F1-216840BFD36C@microsoft.com... > It was the > > propertyValue = property.GetValue(obj, null); > > throw the exception (Nullable object must have a value) before I had a > chance to check if properValue was null or not. > > Any other ideas? Thanks. > > "Henning Krause [MVP - Exchange]" wrote: > >> Hello, >> >> Have you tried this? >> >> if (propertyValue == null) { >> Console.WriteLine("<null>"); >> } >> else >> { >> Console.WriteLine(propertyValue.ToString()); >> } >> >> Best regards, >> Henning Krause >> >> "Andrew" <And***@discussions.microsoft.com> wrote in message >> news:28BFF904-952F-4194-8987-7C7D6D5DD246@microsoft.com... >> > Hello, friends, >> > >> > In the following C# code, I tried to get the values for each property >> > in >> > an >> > object: >> > >> > public void WriteObjectValue(object obj) >> > { >> > Type objectType = obj.GetType(); >> > PropertyInfo[] properties = objectType.GetProperties(); >> > >> > foreach (PropertyInfo property in properties) >> > { >> > System.Object propertyValue = property.GetValue(obj, >> > null); >> > Console.WriteLine(propertyValue.ToString()); >> > } >> > } >> > >> > This worked fine, except in the following situation: >> > >> > If the passed object obj was defined like the follows >> > >> > Public class IntObjClass >> > { >> > int? deptId; >> > int? sectionId; >> > >> > public int DeptId {set {deptId = value;}} >> > public int SectioinId {set {sectionId = value;}} >> > >> > } >> > >> > and only sectionId was assigned a value, say 100, while deptId was left >> > null. >> > >> > At this situation, the foreach loop will throw an exception at >> > System.Object propertyValue = property.GetValue(), >> > complaining deptId was null. >> > >> > Is there a way to get around this? (I don't want to use try{} catch {} >> > to >> > handle this exception) >> > >> > Thanks a lot for your help. >> >> property is not null. It is a valid instantiated object.
Show quote "VJ" wrote: > more like > > if (property == null) { > > } > else > { > > } > > should work > > VJ > > "Andrew" <And***@discussions.microsoft.com> wrote in message > news:200E4804-4C1E-4D2E-93F1-216840BFD36C@microsoft.com... > > It was the > > > > propertyValue = property.GetValue(obj, null); > > > > throw the exception (Nullable object must have a value) before I had a > > chance to check if properValue was null or not. > > > > Any other ideas? Thanks. > > > > "Henning Krause [MVP - Exchange]" wrote: > > > >> Hello, > >> > >> Have you tried this? > >> > >> if (propertyValue == null) { > >> Console.WriteLine("<null>"); > >> } > >> else > >> { > >> Console.WriteLine(propertyValue.ToString()); > >> } > >> > >> Best regards, > >> Henning Krause > >> > >> "Andrew" <And***@discussions.microsoft.com> wrote in message > >> news:28BFF904-952F-4194-8987-7C7D6D5DD246@microsoft.com... > >> > Hello, friends, > >> > > >> > In the following C# code, I tried to get the values for each property > >> > in > >> > an > >> > object: > >> > > >> > public void WriteObjectValue(object obj) > >> > { > >> > Type objectType = obj.GetType(); > >> > PropertyInfo[] properties = objectType.GetProperties(); > >> > > >> > foreach (PropertyInfo property in properties) > >> > { > >> > System.Object propertyValue = property.GetValue(obj, > >> > null); > >> > Console.WriteLine(propertyValue.ToString()); > >> > } > >> > } > >> > > >> > This worked fine, except in the following situation: > >> > > >> > If the passed object obj was defined like the follows > >> > > >> > Public class IntObjClass > >> > { > >> > int? deptId; > >> > int? sectionId; > >> > > >> > public int DeptId {set {deptId = value;}} > >> > public int SectioinId {set {sectionId = value;}} > >> > > >> > } > >> > > >> > and only sectionId was assigned a value, say 100, while deptId was left > >> > null. > >> > > >> > At this situation, the foreach loop will throw an exception at > >> > System.Object propertyValue = property.GetValue(), > >> > complaining deptId was null. > >> > > >> > Is there a way to get around this? (I don't want to use try{} catch {} > >> > to > >> > handle this exception) > >> > > >> > Thanks a lot for your help. > >> > >> > > > Ok Andrew, I think I know the problem.. sorry about confusion. You cannot do
getValue on a property with Set only attributes. It wont work. How you will know a property is read or write is like below property.CanRead or property.CanWrite HTH VJ Show quote "Andrew" <And***@discussions.microsoft.com> wrote in message news:7BC599C5-02D5-484A-B7F0-F5B6FF624692@microsoft.com... > property is not null. It is a valid instantiated object. > > "VJ" wrote: > >> more like >> >> if (property == null) { >> >> } >> else >> { >> >> } >> >> should work >> >> VJ >> >> "Andrew" <And***@discussions.microsoft.com> wrote in message >> news:200E4804-4C1E-4D2E-93F1-216840BFD36C@microsoft.com... >> > It was the >> > >> > propertyValue = property.GetValue(obj, null); >> > >> > throw the exception (Nullable object must have a value) before I had a >> > chance to check if properValue was null or not. >> > >> > Any other ideas? Thanks. >> > >> > "Henning Krause [MVP - Exchange]" wrote: >> > >> >> Hello, >> >> >> >> Have you tried this? >> >> >> >> if (propertyValue == null) { >> >> Console.WriteLine("<null>"); >> >> } >> >> else >> >> { >> >> Console.WriteLine(propertyValue.ToString()); >> >> } >> >> >> >> Best regards, >> >> Henning Krause >> >> >> >> "Andrew" <And***@discussions.microsoft.com> wrote in message >> >> news:28BFF904-952F-4194-8987-7C7D6D5DD246@microsoft.com... >> >> > Hello, friends, >> >> > >> >> > In the following C# code, I tried to get the values for each >> >> > property >> >> > in >> >> > an >> >> > object: >> >> > >> >> > public void WriteObjectValue(object obj) >> >> > { >> >> > Type objectType = obj.GetType(); >> >> > PropertyInfo[] properties = objectType.GetProperties(); >> >> > >> >> > foreach (PropertyInfo property in properties) >> >> > { >> >> > System.Object propertyValue = property.GetValue(obj, >> >> > null); >> >> > Console.WriteLine(propertyValue.ToString()); >> >> > } >> >> > } >> >> > >> >> > This worked fine, except in the following situation: >> >> > >> >> > If the passed object obj was defined like the follows >> >> > >> >> > Public class IntObjClass >> >> > { >> >> > int? deptId; >> >> > int? sectionId; >> >> > >> >> > public int DeptId {set {deptId = value;}} >> >> > public int SectioinId {set {sectionId = value;}} >> >> > >> >> > } >> >> > >> >> > and only sectionId was assigned a value, say 100, while deptId was >> >> > left >> >> > null. >> >> > >> >> > At this situation, the foreach loop will throw an exception at >> >> > System.Object propertyValue = property.GetValue(), >> >> > complaining deptId was null. >> >> > >> >> > Is there a way to get around this? (I don't want to use try{} catch >> >> > {} >> >> > to >> >> > handle this exception) >> >> > >> >> > Thanks a lot for your help. >> >> >> >> >> >> >> sorry, it actually had {get {return ****;}} definitions....
so, ReadOnly was not the reason Show quote "VJ" wrote: > Ok Andrew, I think I know the problem.. sorry about confusion. You cannot do > getValue on a property with Set only attributes. It wont work. How you will > know a property is read or write is like below > > property.CanRead > or > property.CanWrite > > HTH > VJ > > "Andrew" <And***@discussions.microsoft.com> wrote in message > news:7BC599C5-02D5-484A-B7F0-F5B6FF624692@microsoft.com... > > property is not null. It is a valid instantiated object. > > > > "VJ" wrote: > > > >> more like > >> > >> if (property == null) { > >> > >> } > >> else > >> { > >> > >> } > >> > >> should work > >> > >> VJ > >> > >> "Andrew" <And***@discussions.microsoft.com> wrote in message > >> news:200E4804-4C1E-4D2E-93F1-216840BFD36C@microsoft.com... > >> > It was the > >> > > >> > propertyValue = property.GetValue(obj, null); > >> > > >> > throw the exception (Nullable object must have a value) before I had a > >> > chance to check if properValue was null or not. > >> > > >> > Any other ideas? Thanks. > >> > > >> > "Henning Krause [MVP - Exchange]" wrote: > >> > > >> >> Hello, > >> >> > >> >> Have you tried this? > >> >> > >> >> if (propertyValue == null) { > >> >> Console.WriteLine("<null>"); > >> >> } > >> >> else > >> >> { > >> >> Console.WriteLine(propertyValue.ToString()); > >> >> } > >> >> > >> >> Best regards, > >> >> Henning Krause > >> >> > >> >> "Andrew" <And***@discussions.microsoft.com> wrote in message > >> >> news:28BFF904-952F-4194-8987-7C7D6D5DD246@microsoft.com... > >> >> > Hello, friends, > >> >> > > >> >> > In the following C# code, I tried to get the values for each > >> >> > property > >> >> > in > >> >> > an > >> >> > object: > >> >> > > >> >> > public void WriteObjectValue(object obj) > >> >> > { > >> >> > Type objectType = obj.GetType(); > >> >> > PropertyInfo[] properties = objectType.GetProperties(); > >> >> > > >> >> > foreach (PropertyInfo property in properties) > >> >> > { > >> >> > System.Object propertyValue = property.GetValue(obj, > >> >> > null); > >> >> > Console.WriteLine(propertyValue.ToString()); > >> >> > } > >> >> > } > >> >> > > >> >> > This worked fine, except in the following situation: > >> >> > > >> >> > If the passed object obj was defined like the follows > >> >> > > >> >> > Public class IntObjClass > >> >> > { > >> >> > int? deptId; > >> >> > int? sectionId; > >> >> > > >> >> > public int DeptId {set {deptId = value;}} > >> >> > public int SectioinId {set {sectionId = value;}} > >> >> > > >> >> > } > >> >> > > >> >> > and only sectionId was assigned a value, say 100, while deptId was > >> >> > left > >> >> > null. > >> >> > > >> >> > At this situation, the foreach loop will throw an exception at > >> >> > System.Object propertyValue = property.GetValue(), > >> >> > complaining deptId was null. > >> >> > > >> >> > Is there a way to get around this? (I don't want to use try{} catch > >> >> > {} > >> >> > to > >> >> > handle this exception) > >> >> > > >> >> > Thanks a lot for your help. > >> >> > >> >> > >> > >> > >> > > > Andrew <And***@discussions.microsoft.com> wrote:
> sorry, it actually had {get {return ****;}} definitions.... In that case, it's rather hard for us to know what's wrong.> > so, ReadOnly was not the reason Could you post a short but complete program which demonstrates the problem? See http://www.pobox.com/~skeet/csharp/complete.html for details of what I mean by that. -- Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet If replying to the group, please do not mail me too  |
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