If I create a class in C#, how can I serialize/deserialize it to a file? Is this somethat that can be done using built in functionality or is it custom code?
XmlSerializer; note that the exact xml names can be controlled through various attributes, but all you really need is:
a public type
with a default constructor
and public read/write members (ideally properties)
Example:
using System;
using System.Xml;
using System.Xml.Serialization;
public class Person {
public string Name { get; set; }
}
static class Program {
static void Main() {
Person person = new Person { Name = "Fred"};
XmlSerializer ser = new XmlSerializer(typeof(Person));
// write
using (XmlWriter xw = XmlWriter.Create("file.xml")) {
ser.Serialize(xw, person);
}
// read
using (XmlReader xr = XmlReader.Create("file.xml")) {
Person clone = (Person) ser.Deserialize(xr);
Console.WriteLine(clone.Name);
}
}
}
You need to use class XmlSerializer. Main methods are Serialize and Deserialize. They accept streams, text readers\writers and other classes.
Code sample:
public class Program
{
public class MyClass
{
public string Name { get; set; }
}
static void Main(string[] args)
{
var myObj = new MyClass { Name = "My name" };
var fileName = "data.xml";
var serializer = new XmlSerializer(typeof(MyClass));
using (var output = new XmlTextWriter(fileName, Encoding.UTF8))
serializer.Serialize(output, myObj);
using (var input = new StreamReader(fileName))
{
var deserialized = (MyClass)serializer.Deserialize(input);
Console.WriteLine(deserialized.Name);
}
Console.WriteLine("Press ENTER to finish");
Console.ReadLine();
}
}
Related
I try to save an object to an XML Document.
I always get an inner Exception Error.
I think it has to do something with boxing and unboxing but i cannot help myself.
So here we go:
The Method for XML Saving
public class Saveclass
//
public static void Save(string filename, List<Class> classlist)
{
StreamWriter writer = new StreamWriter(filename, false, Encoding.UTF8);
XmlSerializer serializer = new XmlSerializer(typeof(class));
serializer.Serialize(writer,classlist);//Here i get the error at classlist
writer.Close();
}
And here the SaveFile Dialog
private void SaveButton(object sender, EventArgs e)
{
SaveFileDialog dialog = new SaveFileDialog();
dialog.Filter = "XML Data|*.xml";
if (dialog.ShowDialog() == DialogResult.OK)
{
List<class> classlist = null;
foreach (ListViewItem item in this.listViewWinforms.Items)
{
classlist = new List<class>();
}
Saveclass.Save(dialog.FileName, classlist)
}
}
In the Basic i have a Listview with Items inside and want to save these Items in my listview to an XML Document
Error is
System.InvalidOperationException: 'Trying to generate an XML Document
InvalidCastException: The object of the Type "System.Collections.Generic.List`1[Namespace.Class]" cannot cast into"Namespace.Class"
There is a type mismatch.
You are defining your serializer as:
new XmlSerializer(typeof(class));
Which is configured to serialize objects of type class.
However, you are then trying to serialize the classlist object, which is not a class but a List<Class>.
Try defining your serializer as:
new XmlSerializer(typeof(List<Class>));
By the way, naming your class class is very confusing. You should try to name your classes more descriptively.
I think you need to change just one line:
Just use typeof(List) instead of typeof(class))
XmlSerializer serializer = new XmlSerializer(typeof(List<Class>));
Here is a small example
using System;
using System.Collections.Generic;
using System.Text;
using System.Xml.Serialization;
using System.IO;
namespace ConsoleApplication1
{
public class Program
{
public static void Main(string[] args)
{
List<Car> myList = new List<Car>();
myList.Add(new Car(){ Name = "Beetle", Brand = "VW", Price = 5999.9M });
myList.Add(new Car(){ Name = "Corolla", Brand = "Toyota", Price = 49999.9M });
Saveclass.Save("carlist.xml",myList);
}
}
public static class Saveclass
{
public static void Save(string filename, List<Car> classlist)
{
StreamWriter writer = new StreamWriter(filename, false, Encoding.UTF8);
XmlSerializer serializer = new XmlSerializer(typeof(List<Car>));
serializer.Serialize(writer,classlist);
writer.Close();
}
}
public class Car
{
public string Name {get;set;}
public string Brand {get; set;}
public decimal Price {get; set;}
}
}
You can test here
I've got a simple .Net framework C# console app that serializes a a class that is of a derived type, where a property is also of a derived type.
The derived classes have names that are the same as the base class, but are in a different namespace to prevent them from clashing. It seems though that the reflection the XmlSerializer uses does not work with this too well. Maybe there is some way of wrangling the attributes that I can still end up with the base class using pretty names (as it will be a DLL interface when used) and the XML also using pretty names (as it will be human editable)... pretty names for the derived classes are not required (though would be a bonus).
The XML would hopefully look like:
<?xml version="1.0" encoding="utf-8"?>
<Person xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<Details>
<Detail>
<Description>bald</Description>
</Detail>
<Detail>
<Description>red tie</Description>
</Detail>
</Details>
</Person>
But the closest I can get without exceptions is where the <Detail> elements are
<Detail xsi:type="DerivedDetail"> ... </Detail>
Having to add this xs:type attribute is not the best for human-editable XML.
This is achieved with the below C# code. If I remove the marked XmlType attribute then the element should serialize without the xsi:type attribute, but instead I get an exception:
InvalidOperationException: Types 'Test.Detail' and 'Test.Xml.Detail' both use the XML type name, 'Detail', from namespace ''. Use XML attributes to specify a unique XML name and/or namespace for the type.
I tried marking the derived Xml.Detail class as an anonymous XML type but then the exception reads:
InvalidOperationException: Cannot include anonymous type 'Test.Xml.Detail'.
I have read many similar questions but have not encountered anything that solves this just yet.
In this code below Person is an abstract class that has a property that is an array of the abstract type Detail. These types are derived by Xml.Person and Xml.Detail respectively. The program creates a test Xml.Person object and attempts to serialize it:
using System;
using System.Text;
using System.IO;
using System.Xml;
using System.Xml.Serialization;
namespace Test
{
class Program
{
static void Main(string[] args)
{
// Create test details array
var TestDetails = new Xml.Detail[]
{
new Xml.Detail
{
Description = "bald"
},
new Xml.Detail
{
Description = "red tie"
}
};
// create test person object that holds details array
var TestBar = new Xml.Person()
{
Details = TestDetails
};
// serialize the person object
var s = new Xml.Serializer();
var TestOutput = s.Serialize(TestBar);
Console.WriteLine(TestOutput);
}
}
// base classes
public abstract class Person
{
public abstract Detail[] Details { get; set; }
}
public abstract class Detail
{
public abstract string Description { get; set; }
}
namespace Xml
{
// derived classes
[Serializable]
[XmlType(AnonymousType = true)]
[XmlRoot(IsNullable = false)]
public class Person : Test.Person
{
[XmlArrayItem("Detail", typeof(Detail))]
[XmlArray(IsNullable = false)]
public override Test.Detail[] Details { get; set; }
}
// This attribute makes serialization work but also adds the xsi:type attribute
[XmlType("DerivedDetail")]
[Serializable]
public class Detail : Test.Detail
{
public override string Description { get; set; }
}
// class that does serializing work
public class Serializer
{
private static XmlSerializer PersonSerializer =
new XmlSerializer(typeof(Person), new Type[] { typeof(Detail) });
public string Serialize(Test.Person person)
{
string Output = null;
var Stream = new MemoryStream();
var Encoding = new UTF8Encoding(false, true);
using (var Writer = new XmlTextWriter(Stream, Encoding))
{
Writer.Formatting = Formatting.Indented;
PersonSerializer.Serialize(Writer, person);
Output = Encoding.GetString(Stream.ToArray());
}
Stream.Dispose();
return Output;
}
}
}
}
Not sure why you're using base classes instead of interfaces when you don't have any member fields. Regardless, I assumed you wanted Xml.Person to be a concrete instantiation of abstract Person or any classes derived from abstract Person without decorating abstract Person with XML attributes. I accomplished this by forcing abstract Person to become a concrete instantiation of Xml.Person before serializing it. Please replace XmlSerializationProject with Test.
using System;
using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Serialization;
namespace XmlSerializationProject
{
class Program
{
static void Main(string[] args)
{
// Create test details array
var TestDetails = new Xml.Detail[]
{
new Xml.Detail
{
Description = "bald"
},
new Xml.Detail
{
Description = "red tie"
}
};
// create test person object that holds details array
var TestBar = new Xml.Person()
{
Details = TestDetails
};
// serialize the person object
var s = new Xml.Serializer();
var TestOutput = s.Serialize(TestBar);
Console.WriteLine(TestOutput);
Console.ReadKey();
}
}
// base classes
public abstract class Person
{
public abstract Detail[] Details { get; set; }
}
public abstract class Detail
{
public abstract string Description { get; set; }
}
namespace Xml
{
[Serializable]
[XmlType(AnonymousType = true)]
[XmlRoot(IsNullable = false)]
public class Person : XmlSerializationProject.Person
{
public Person()
{ }
public Person(XmlSerializationProject.Person person)
{
// Deep copy
if (person.Details == null) return;
this.Details = new Detail[person.Details.Length];
for (int i = 0; i < person.Details.Length; i++)
{
this.Details[i] = new Detail { Description = person.Details[i].Description };
}
}
[XmlArray(ElementName = "Details")]
[XmlArrayItem("Detail", typeof(Detail))]
[XmlArrayItem("ODetail", typeof(XmlSerializationProject.Detail))]
public override XmlSerializationProject.Detail[] Details
{
get;
set;
}
}
[Serializable]
public class Detail : XmlSerializationProject.Detail
{
public override string Description { get; set; }
}
// class that does serializing work
public class Serializer
{
private static readonly XmlSerializer PersonSerializer;
private static Serializer()
{
var xmlAttributeOverrides = new XmlAttributeOverrides();
// Change original "Detail" class's element name to "AbstractDetail"
var xmlAttributesOriginalDetail = new XmlAttributes();
xmlAttributesOriginalDetail.XmlType = new XmlTypeAttribute() { TypeName = "AbstractDetail" };
xmlAttributeOverrides.Add(typeof(XmlSerializationProject.Detail), xmlAttributesOriginalDetail);
// Ignore Person.Details array
var xmlAttributesOriginalDetailsArray = new XmlAttributes();
xmlAttributesOriginalDetailsArray.XmlIgnore = true;
xmlAttributeOverrides.Add(typeof(XmlSerializationProject.Person), "Details", xmlAttributesOriginalDetailsArray);
PersonSerializer = new XmlSerializer(
typeof(Person), xmlAttributeOverrides, new Type[] { typeof(Detail) }, new XmlRootAttribute(), "default");
}
public string Serialize(XmlSerializationProject.Person person)
{
return Serialize(new Person(person));
}
public string Serialize(Person person)
{
string Output = null;
var Stream = new MemoryStream();
var Encoding = new UTF8Encoding(false, true);
using (var Writer = new XmlTextWriter(Stream, Encoding))
{
Writer.Formatting = Formatting.Indented;
PersonSerializer.Serialize(Writer, person);
Output = Encoding.GetString(Stream.ToArray());
}
Stream.Dispose();
return Output;
}
}
}
}
I'm trying to deserialize a bunch of data that was serialized by an old version of the code. When the data was serialized the classes had a different structure from the current class structure. To keep this data working in my new code, I hade to add the old classes structure to the code just for import this serialized data. I'm calling this classes as 'class'_oldVersions. To deserialize, I'm using this code:
className_oldVersions temp_className = new className_oldVersions();
XmlSerializer testSerializer = new XmlSerializer(typeof(className_oldVersions),
new XmlRootAttribute { ElementName = "className" });
temp_className = (ObservedData_OldVersions)testSerializer.Deserialize(ms_MemoryStream);
This code works fine, and I can deserialize the data using a diffent class name from the original. My problem is when I try to use this same procedure to deserialize an observable collection.
I created a code that reproduce my problem. In this code I serialize an observable collection of class OptimizationVariables and I would like to deserialize to an observable collection of class OptimizationVariablies_NewClass that has similar structure from the original one.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading.Tasks;
using System.Xml.Serialization;
using System.Collections.ObjectModel;
public class OptimizationVariables
{
public string VariableName { get; set; }
}
public class OptimizationVariables_NewClass
{
public string VariableName { get; set; }
}
public class ModelsCollection
{
private ModelsCollection()
{
}
private ObservableCollection<OptimizationVariables> m_optimizationVariables =
new ObservableCollection<OptimizationVariables>();
public ObservableCollection<OptimizationVariables> OptimizationVariables
{
get { return m_optimizationVariables; }
set { m_optimizationVariables = value; }
}
private ObservableCollection<OptimizationVariables_NewClass> m_optimizationVariables_NewClass =
new ObservableCollection<OptimizationVariables_NewClass>();
public ObservableCollection<OptimizationVariables_NewClass> OptimizationVariables_NewClass
{
get { return m_optimizationVariables_NewClass; }
set { m_optimizationVariables_NewClass = value; }
}
}
class Program
{
static void Main(string[] args)
{
//Here I serialize an ObservableCollection of 2 OptimizationVariables instances
Serialize();
//Here I deserialize for the same class and works fine
Deserialize();
//Here I try to deserialize to a new class with same structure, but different name. I a have an error.
Deserialize2NewClass();
}
static void Serialize()
{
MemoryStream ms;
ObservableCollection<OptimizationVariables> OptimizationVariables2Serialize = new ObservableCollection<OptimizationVariables>();
OptimizationVariables opt_var1 = new OptimizationVariables();
opt_var1.VariableName = "Variable Name 1";
OptimizationVariables2Serialize.Add(opt_var1);
OptimizationVariables opt_var2 = new OptimizationVariables();
opt_var1.VariableName = "Variable Name 2";
OptimizationVariables2Serialize.Add(opt_var1);
ms = new MemoryStream();
XmlSerializer serializer = new XmlSerializer(typeof(ObservableCollection<OptimizationVariables>));
serializer.Serialize(ms, OptimizationVariables2Serialize);
TextWriter sw = new StreamWriter("XML_File_x64.bin");
sw.WriteLine(Convert.ToBase64String(ms.ToArray()));
sw.Close();
}
static void Deserialize()
{
byte[] memoryData;
MemoryStream ms;
TextReader sw = new StreamReader("XML_File_x64.bin");
memoryData = Convert.FromBase64String(sw.ReadLine());
ms = new MemoryStream(memoryData);
ObservableCollection<OptimizationVariables> OptimizationVariablesDeserialized = new ObservableCollection<OptimizationVariables>();
XmlSerializer deserializer = new XmlSerializer(typeof(ObservableCollection<OptimizationVariables>));
OptimizationVariablesDeserialized = (ObservableCollection<OptimizationVariables>)deserializer.Deserialize(ms);
Console.Write(OptimizationVariablesDeserialized.Count());
sw.Close();
}
static void Deserialize2NewClass()
{
byte[] memoryData;
MemoryStream ms;
TextReader sw = new StreamReader("XML_File_x64.bin");
memoryData = Convert.FromBase64String(sw.ReadLine());
ms = new MemoryStream(memoryData);
ObservableCollection<OptimizationVariables_NewClass> OptimizationVariablesDeserialized = new ObservableCollection<OptimizationVariables_NewClass>();
XmlSerializer deserializer = new XmlSerializer(typeof(ObservableCollection<OptimizationVariables_NewClass>));
OptimizationVariablesDeserialized = (ObservableCollection<OptimizationVariables_NewClass>)deserializer.Deserialize(ms);
Console.Write(OptimizationVariablesDeserialized.Count());
sw.Close();
}
}
The problem in your code is that the class OptimizationVariables name is saved in the xml data when serializing. but for deserialization it expects a OptimizationVariables_NewClass name which is not within the xml file.
consider the fact that not only the variable names, but also the class names will be used when serializing a class or struct...
So, just changed your code to make it save the data in readable xml file, then replacing "OptimizationVariables" with "OptimizationVariables_NewClass" solved the error:
using System;
using System.Linq;
using System.IO;
using System.Xml.Serialization;
using System.Collections.ObjectModel;
public class OptimizationVariables
{
public string VariableName { get; set; }
}
public class OptimizationVariables_NewClass
{
public string VariableName { get; set; }
}
public class ModelsCollection
{
private ModelsCollection()
{
}
private ObservableCollection<OptimizationVariables> m_optimizationVariables =
new ObservableCollection<OptimizationVariables>();
public ObservableCollection<OptimizationVariables> OptimizationVariables
{
get { return m_optimizationVariables; }
set { m_optimizationVariables = value; }
}
private ObservableCollection<OptimizationVariables_NewClass> m_optimizationVariables_NewClass =
new ObservableCollection<OptimizationVariables_NewClass>();
public ObservableCollection<OptimizationVariables_NewClass> OptimizationVariables_NewClass
{
get { return m_optimizationVariables_NewClass; }
set { m_optimizationVariables_NewClass = value; }
}
}
class Program
{
static void Main(string[] args)
{
Serialize();
Deserialize();
Deserialize2NewClass();
}
static void Serialize()
{
ObservableCollection<OptimizationVariables> OptimizationVariables2Serialize = new ObservableCollection<OptimizationVariables>();
OptimizationVariables opt_var1 = new OptimizationVariables();
opt_var1.VariableName = "Variable Name 1";
OptimizationVariables2Serialize.Add(opt_var1);
OptimizationVariables opt_var2 = new OptimizationVariables();
opt_var1.VariableName = "Variable Name 2";
OptimizationVariables2Serialize.Add(opt_var1);
TextWriter writer = new StreamWriter("XML_File.xml");
XmlSerializer serializer = new XmlSerializer(typeof(ObservableCollection<OptimizationVariables>));
serializer.Serialize(writer, OptimizationVariables2Serialize);
writer.Close();
}
static void Deserialize()
{
TextReader sw = new StreamReader("XML_File.xml");
ObservableCollection<OptimizationVariables> OptimizationVariablesDeserialized = new ObservableCollection<OptimizationVariables>();
XmlSerializer deserializer = new XmlSerializer(typeof(ObservableCollection<OptimizationVariables>));
OptimizationVariablesDeserialized = (ObservableCollection<OptimizationVariables>)deserializer.Deserialize(sw);
Console.Write(OptimizationVariablesDeserialized.Count());
sw.Close();
}
static void Deserialize2NewClass()
{
TextReader sw = new StreamReader("XML_File.xml");
var str = sw.ReadToEnd();
sw.Close();
str = str.Replace("OptimizationVariables", "OptimizationVariables_NewClass");
var stream = new StringReader(str);
ObservableCollection<OptimizationVariables_NewClass> OptimizationVariablesDeserialized = new ObservableCollection<OptimizationVariables_NewClass>();
XmlSerializer deserializer = new XmlSerializer(typeof(ObservableCollection<OptimizationVariables_NewClass>));
OptimizationVariablesDeserialized = (ObservableCollection<OptimizationVariables_NewClass>)deserializer.Deserialize(stream);
Console.Write(OptimizationVariablesDeserialized.Count());
}
}
now it works fine!
I got some issues with the XmlSerializer in .NET.
Here I have a small example I built up just right now. (also available # gist https://gist.github.com/2d84be9041a3f9c06237)
using System.IO;
using System.Xml.Serialization;
namespace XmlSerializingSample
{
internal class Program
{
private static void Main(string[] args)
{
var specialType = new SpecialType()
{
Id = 1,
Name = "test"
};
var serializer = new XmlSerializer(typeof (SpecialType));
var des = new XmlSerializer(typeof (BaseType));
using (var memeStream = new MemoryStream())
{
serializer.Serialize(memeStream, specialType);
memeStream.Flush();
memeStream.Seek(0, SeekOrigin.Begin);
var instance = des.Deserialize(memeStream); // Here it throws the exception
}
}
}
[XmlInclude(typeof(SpecialType))]
[XmlType("baseType")]
public class BaseType
{
public long Id { get; set; }
}
[XmlRoot("special")]
public class SpecialType : BaseType
{
public string Name { get; set; }
}
}
In line 24 of the code I get an InvalidOperationException stating "{"<special xmlns=''> wurde nicht erwartet."}" [yes, it's german]
All Posts I found stated, after adding XmlIncludeAttribute on the base type being deserialized, this should work. Did I forget sth.?
Regards,
MacX
The problem is that your Serializer is serializing the SpecialType with a root element as so:
<special ...>
<Id>...
But then you try to Deserialize it using var des = new XmlSerializer(typeof (BaseType)); it knows about both types but it doesn't know how to handle the root element in the xml.
If you want this to work, you need to also set the root element of the base type to serialize as special. In other words, you would need to do this:
[XmlInclude(typeof(SpecialType))]
[XmlType("baseType")]
[XmlRoot("special")]
public class BaseType
{
public long Id { get; set; }
}
That way, the deserializer knows how to handle special as the root element.
I don't think there are other simple alternatives to make this work out of the box.
Update
This is another alternative using the XmlAttributeOverrides class.
LinqPad code:
void Main()
{
var specialType = new SpecialType()
{
Id = 1,
Name = "test"
};
var serializer = new XmlSerializer(typeof (SpecialType));
XmlAttributeOverrides attrOverrides = new XmlAttributeOverrides();
XmlAttributes attrs = new XmlAttributes();
// Create an XmlRootAttribute to override.
XmlRootAttribute attr = new XmlRootAttribute();
attr.ElementName = "special";
// Add the XmlRootAttribute to the collection of objects.
attrs.XmlRoot=attr;
attrOverrides.Add(typeof(BaseType), attrs);
var des = new XmlSerializer(typeof (BaseType), attrOverrides);
using (var memeStream= new MemoryStream())
{
serializer.Serialize(memeStream, specialType);
memeStream.Flush();
memeStream.Seek(0, SeekOrigin.Begin);
var instance = des.Deserialize(memeStream);
}
}
[XmlInclude(typeof(SpecialType))]
[XmlType("baseType")]
public class BaseType
{
public long Id { get; set; }
}
[XmlRoot("special")]
public class SpecialType : BaseType
{
public string Name { get; set; }
}
How do I serialize an XML-serializable object to an XML fragment (no XML declaration nor namespace references in the root element)?
Here is a hack-ish way to do it without having to load the entire output string into an XmlDocument:
using System;
using System.Text;
using System.Xml;
using System.Xml.Serialization;
public class Example
{
public String Name { get; set; }
static void Main()
{
Example example = new Example { Name = "Foo" };
XmlSerializer serializer = new XmlSerializer(typeof(Example));
XmlSerializerNamespaces emptyNamespace = new XmlSerializerNamespaces();
emptyNamespace.Add(String.Empty, String.Empty);
StringBuilder output = new StringBuilder();
XmlWriter writer = XmlWriter.Create(output,
new XmlWriterSettings { OmitXmlDeclaration = true });
serializer.Serialize(writer, example, emptyNamespace);
Console.WriteLine(output.ToString());
}
}
You should be able to just serialize like you usually do, and then use the Root property from the resulting document.
You may need to clear the attributes of the element first.
By the way this is awesome.
I implemented this code to make it easy to work with xml fragments as classes quickly and then you can just replace the node when finished. This makes the transition between code and xml ultra-easy.
First create some extension methods.
public static class SerializableFragmentExtensions
{
public static XElement ToElement(this ISerializableFragment iSerializableFragment)
{
var serializer = new XmlSerializer(iSerializableFragment.GetType());
var emptyNamespace = new XmlSerializerNamespaces();
emptyNamespace.Add(String.Empty, String.Empty);
var output = new StringBuilder();
var writer = XmlWriter.Create(output,
new XmlWriterSettings { OmitXmlDeclaration = true });
serializer.Serialize(writer, iSerializableFragment, emptyNamespace);
return XElement.Parse(output.ToString(), LoadOptions.None);
}
public static T ToObject<T>(this XElement xElement)
{
var serializer = new XmlSerializer(typeof (T));
var reader = xElement.CreateReader();
var obj = (T) serializer.Deserialize(reader);
return obj;
}
}
Next Implement the required interface (marker interface--I know you are not supposed to but I think this is the perfect reason to it.)
public interface ISerializableFragment
{
}
Now all you have to do is decorate any Serializable class, you want to convert to an XElement Fragment, with the interface.
[Serializable]
public class SomeSerializableClass : ISerializableFragment
{
[XmlAttribute]
public string SomeData { get; set; }
}
Finally test the code.
static void Main(string[] args)
{
var someSerializableClassObj = new SomeSerializableClass() {SomeData = "Testing"};
var element = someSerializableClass.ToElement();
var backToSomeSerializableClassObj = element.ToObject<SomeSerializableClass>();
}
Thanks again for this amazingly useful code.