I'm a little inexperienced with the DataContract paradigm, and I'm running into a deserialization problem. I have a field that's a string, but it contains xml and it's not being deserialized correctly. I have a feeling that it's because the DCS is treating it as input to the serializer and not as an opaque string object.
Is there some way to mark a DataMember in code to say "This thing is a string, don't treat its contents as xml" similar to XmlIgnore?
Thanks!
Well, the equivalent to [XmlIgnore] is just not putting a [DataMember] on your property/field - if you're decorating everything with [DataMember] otherwise.
But I don't see how you could tell the DataContractSerializer to treat the property as an opaque string and nothing else.
You could try to have a separate property which adds <![CDATA[ before and ]]> after your content string, and serialize that property instead of your raw XML property (by decorating that new property with the [DataMember] attribute).
Something like this:
public string XmlContent { get; set; }
[DataMember]
public string XmlContentSafe
{
get { return "<![CDATA[" + XmlContent + "]]>"; }
}
Maybe that way you can trick the DCS ? (never tried it myself - just guessing....)
Turns out the easiest way to do this was just to cast the xml field coming from sql server to a varchar(max) when retrieving it from the database.
CAST(CONVERT(XML,[RawXml],0) AS VARCHAR(MAX)) AS RawXml
In this case, the serializer seems to be ignoring it as desired.
Thanks for the help though!
There is an easy way to do, just declare the property with raw XML as XmlElement
[DataMember]
public XmlElement RawXML { private get; set; }
Related
One of my WCF endpoints has this method:
GetData(DataTable dt)
I tried to create a class on the client that inherits from the DataTable class
public class ExtendedDataTable : DataTable{
//...implementation
}
and pass it along with the endpoint call:
GetData(new ExtendedDataTable());
Then I got the SerializationException. Accordingly to the error, it suggests that I use either DataContractResolver or the KnownType attribute.
I don't want to use the KnownType, because I shouldn't have to update the endpoint every time someone decides to inherit my DataContract. I can't write any DataContractResolver, because I didn't extend the exact structure of the DataTable class. Is it possible to to extend a DataContract from the client?
If so, what's the best practice?
Thanks!
I don't recommend using the Datatable, which makes it easy for WCF to have problems with client and server serialization, such as the need to specify a table name. It is best to use a custom data type, we can use the inheritance type with the KnownType attribute.
https://learn.microsoft.com/en-us/dotnet/framework/wcf/feature-details/data-contract-known-types
On my side, I can't use the inherited Datatable, while I could use an arbitrary custom class by using Knowntype attribute.
Please refer to my code segments.
[DataContract]
[KnownType(typeof(Product))]
public class MyData
{
[DataMember]
public ProductBase Product { get; set; }
}
[DataContract]
public class ProductBase
{
[DataMember]
public int ID { get; set; }
}
[DataContract]
public class Product : ProductBase
{
[DataMember]
public string Name { get; set; }
}
You can try to inherit DataTable and explicitly use DataContract attribute to declare it's name as "DataTable".
But I'm not sure about purpose of this replacement. Server side will see only what is related to original data contract. Even when new properties gets serialized, deserializatin will only work for server side properties. Unless some custom deserialization will be provided.
In all scenarios, using DataTable is not good idea at all as Abraham Qian already pointed out.
I have a question about the [DataContract] attribute.
I have written my code like below: here I am not using [DataContract] attribute for my test class.
class test
{
[Datamember]
public string Strproperty
{
get;
set;
}
[Datamemer]
public string Strproperty2
{
get;
set;
}
}
class checktotal:Iservice
{
public string testmethod(test obj)
{
return obj.Strproperty+Strproperty2;
}
}
For that I am sending data from client I am getting the values correctly.
Here is it necessary to use [DataContract] attribute for that test class?
If I removed [Datamember] for test class property is getting error while sending from client. But I am not getting any errors even if I am not using the [DataContract] attribute.
Please give me a brief explanation with example so that I can understand when to give that attribute and when do not give that attribute.
Thanks,
Satya Pratap.
The DataContractSerializer can deal with classes that do not have the DataContract attribute if they provide a default constructor. See the MSDN documentation for more details.
As of .NET 3.5 Service Pack 1, you can omit (not use) the [DataContract] and [DataMember] attributes. If you do that, then the DataContractSerializer in WCF will behave just like the XML serializer - it will serialize all public properties only.
I prefer to use [DataContract] and [DataMember] explicitly anyway - it gives me the opportunity to specify options (like the data contract's XML namespace, the order of the [DataMember]) and it lets me e.g. also exclude certain properties from serialization.
As soon as you start using [DataMember] on one property, then only those properties decorated with a [DataMember] will be looked at for the WCF serialization.
Is it possible to hide a class' data member from client applications but still serialize with XmlSerializer?
The context is that I'm getting an address in pieces but need to concatenate many of those pieces into a single string before serializing the object to XML and passing it along to something else.
The address class is in turn part of a larger class so simply inheriting and adding this bit is more complicated were it not nested and my need isn't great enough to warrant writing a custom serializer.
Sample:
[DataContract]
public class Address
{
[DataMember()]
public string City
[DataMember()]
public string State
[DataMember()]
public string StreetDirection
[DataMember()]
public string StreetName
[DataMember()]
public string StreetNumber
[DataMember()]
public string StreetSuffix
[DataMember()]
public string Unit
[DataMember()]
public string Zip
[IgnoreDataMember()]
[Serializable]
public string AddressLine1
}
Basically, I want to have a placeholder (AddressLine1) where I can put the concatenation of StreetXXX properties before passing along (and it's already if the receiver sees the individual pieces).
Edit - add example
Input would be something like:
<Address>
<StreetNumber>123</StreetNumber>
<StreetDirection>S.</StreetDirection>
<StreetName>Main</StreetName>
<StreetSuffix>St.</StreetSuffix>
<Unit>207</Unit>
<City>Denver</City>
<State>CO</State>
<Zip>80123</Zip>
</Address>
But I'd want to wind up serializing to:
<Address>
<StreetNumber>123</StreetNumber>
<StreetDirection>S.</StreetDirection>
<StreetName>Main</StreetName>
<StreetSuffix>St.</StreetSuffix>
<Unit>207</Unit>
<City>Denver</City>
<State>CO</State>
<Zip>80123</Zip>
<AddressLine1>123 S. Main St.</AddressLine1>
</Address>
Thanks,
John
Your question is a bit confusing because you mention the XmlSerializer but you show a DataContract class. Is the data being deserialized (read) and serialized (written) with the same serializer? If so, is it the DataContractSerializer or the XmlSerializer? Or are you trying to read with the DataContractSerializer and write with the XmlSerializer? Anyway, assuming the simple case, that you both read and write using the DataContractSerializer, all you need to do is to make AddressLine1 into a property with a getter and setter and mark it with [DataMember(IsRequired=false)]. Then, in the AddressLine1 property getter, put your address concatenation code, and in the property setter just do nothing. This way, on deserialization, AddressLine1 will just be ignored (even if it's not present at all in the XML it won't cause an error), but on serialization it will be correctly written out.
I would have thought that you would not need to serialize the AddressLine1 property at all and simply have it as a helper read-only property.
[IgnoreDataMember()]
public string AddressLine1
{
get
{
return StreetNumber + " " + StreetDirection + " " + StreetName + " " + StreetSuffice;
}
}
As the value can be constructed whenever it is needed there is no point in serializing and transferring it in addition to the street set of properties. Of course, you could make the implemention more efficient by caching the value and only recreating it when one of the street properties actually changes.
The sample apps include a Suspension Manager class that stores session state in a Dictionary, but never attempt to store anything except a string in it.
Whenever I store anything else but a string, then trigger the serialization, I get the following error
Type 'System.RuntimeType' with data contract name 'RuntimeType:http://schemas.datacontract.org/2004/07/System' is not expected. Consider using a DataContractResolver or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.
Do I have to do something else to be able to store other types in SessionState?
You will need to do two things:
Firstly, ensure the type you are (de)serializing is decorated with the DataContract attribute from System.Runtime.Serialization and ensure it's members are decorated appropriately. For example in c#:
[DataContract]
public struct Product
{
[DataMember]
public Guid Id { get; set; }
[DataMember]
public DateTime ManufactureDate { get; set; }
[DataMember]
public decimal Cost { get; set; }
}
Secondly you will need to call SessionManager's AddKnownType<T>() (with T being the type you need) before attempting to (de)serialize it.
looking at the SessionManager code it is only string types, guess you will have to 'roll your own'
http://code.msdn.microsoft.com/windowsapps/ApplicationData-sample-fb043eb2/sourcecode?fileId=43552&pathId=6033729
Can I have a data contract of this shape??
[DataContract]
public class YearlyStatistic{
[DataMember]
public string Year{get;set;}
[DataMember]
public string StatisticName {get;set;}
[DataMember]
public List<MonthlyStatistic> MonthlyStats {get;set}
};
I am assuming here that class MonthlyStatistic will also need to be a DataContract. Can you do this in a web service?
To use the same model for web services, mark your class as Serializable use the XmlRoot and XmlElement in the System.Xml.Serialization namespace. Here is a sample using your example:
[Serializable]
[XmlRoot("YearlyStatistic")]
public class YearlyStatistic
{
[XmlElement("Year")]
public string Year { get; set; }
[XmlElement("StatisticName")]
public string StatisticName { get; set; }
[XmlElement("MonthlyStats")]
public List<MonthlyStatistic> MonthlyStats { get; set; }
}
You will have to do the same thing for your complex object properties of the parent object.
Yep, thats standard WCF serialization right there. Are you trying to say the MonthlyStats collection has a property called WeeklyStats, or that each individual MonthlyStatistic has a WeeklyStat collection? If its the former, that doesnt work in WCF natively. You will have to do some fiddling in order to get it to work. If its the latter, its perfectly fine.
Yes, you can send the data contract you mentioned above back and forth from a WCF service. Like you said, MonthlyStatistic and all its members will have to be defined as data contracts themselves or be built in types (like strings).
You can even send and receive more complex types like when you have a base class but want to send or receive an object of a derived class (you would do that using the KnownType attribute). While receiving (de-serialization), from Javascript, there's a trick using which you have to specify the type for WCF. If you are interested, feel free to ask.