I would like to know what is the fastest and most lightweight technique to convert a fairly large class to XML. The class will have lists and arrays in it. I need to convert all this data to XML
Here is what my application does:
it will get all the information from the database using linq to enties. Then store the data in a class. Then I want to convert this class to XML. When the data is in XML I will send the XML to the browser along with the xsl stylesheet to be displayed to the user. What is the fastest way to do this.
The XmlSerializer actually creates an assembly (with an XmlSerializationWriter) that is custom made to serialize your class. You can look at the generated code by following these steps.
You only pay the price the first time it encounters a new type.
So I think that you should really go with the XmlSerializer, not only for performance, but for maintainability.
You can use a mixin-like serializer class:
public interface MXmlSerializable { }
public static class XmlSerializable {
public static string ToXml(this MXmlSerializable self) {
if (self == null) throw new ArgumentNullException();
var serializer = new XmlSerializer(self.GetType());
using (var writer = new StringWriter()) {
serializer.Serialize(writer, self);
return writer.GetStringBuilder().ToString();
}
}
}
public class Customer : MXmlSerializable {
public string Name { get; set; }
public bool Preferred { get; set; }
}
// ....
var customer = new Customer {
Name = "Guybrush Threepwood",
Preferred = true };
var xml = customer.ToXml();
The fastest way is to write the code for it yourself. That will remove any overhead, like the need to use reflection to read the properties of the object, as you can access the properties directly.
Add a method to the class that returns it's data as XML, either by returning an XDocument, the XML already formatted as a string, or you can pass an XmlWriter to the method.
By "fastest" do you mean you want the approach which will be fastest to develop? Or do you want the approach which will have the fastest execution speed?
If it's the former, I recommend just using .NET's XmlSerializer class: http://msdn.microsoft.com/en-us/library/system.xml.serialization.xmlserializer.aspx
Serializing a class to XML output is as simple as:
XmlSerializer serializer = new XmlSerializer(myObject.GetType());
serializer.Serialize(Response.OutputStream, myObject);
And there are various attributes you can decorate your class with to control things like whether individual properties are serialized as elements or attributes, etc.
There's a good FAQ at http://www.devolutions.net/articles/serialization.aspx also
You could use XML serialization, for example:
Foo foo = new Foo();
XmlSerializer serializer = new XmlSerializer(typeof(Foo));
TextWriter writer = new StringWriter();
serializer.Serialize(writer, foo);
string xml = writer.ToString();
The fastest method would depend on the class, because it would be hand-written to take advantage of knowledge of the specifics of that class in ways a more general approach couldn't do.
I'd probably use XmlTextWriter rather than straight to TextWriter though. While the latter would allow for some further savings, these would be minimal compared to the better structure of XmlTextWriter, and you've already sacrificed a good bit in terms of structure and ease of maintenance as it is.
You can always slot in your super-optimised implementation of XmlWriter afterwards ;)
It sounds like a rather convoluted set-up, when you could just display the class's information on a webpage using ASP.NET MVC. Why take the extra two steps of converting it to XML, send it to the browser, and use an XSL stylesheet to display it to the user? It doesn't make sense.
I wrote a program that serialized one simple object graph to XML in different ways:
1. Using XmlSerializer
2. Using hardcoded xml serializer
30,000 documents:
XmlSerializer took : 0.9 sec
Hardcoded serializer took: 0.45 sec
I relied on XmlWriter in both cases and that adds some overhead.
Note that you can instruct Visual Studio to generate the XmlSerializer assembly during compile time in order to reduce the serialization for that first instance (otherwise an assembly is generated in runtime).
Related
EDIT 2
I am updating the question again to more simply explain what I need.
I need to take any EntityObject in my application, convert it to XML, which can be reconverted back to AN object later that can be queried or used in a DataSource. I cannot reconvert to the original EntityObject because the structure of that object may have changed. Is this doable?
Original Question below
Let's assume for a second that I am required by someone higher up than me (because I am) to take an EntityObject and convert it to a DataTable. The example I was sent on how to do it is from 2006 and uses a custom class (which my boss thought was built into .Net) and it doesn't work anyway.
Is there a way to do this without writing my own custom class? Something as simple as "new DataTable(myEntityObject)" would be amazing. I'm guessing no though.
EDIT
I have changed the question because I was given the criteria wrong. Mainly we want our EntityObject to be XML so it can be stored in a database and reconstructed later. Can that be done via Serialization?
To answer your updated question:
Use the XmlSerializer
public XElement XmlSerialize(object o)
{
XmlSerializer serializer = new XmlSerializer(o.GetType());
using (StringWriter sw = new StringWriter())
{
serializer.Serialize(sw, o);
return XElement.Parse(sw.ToString());
}
}
No there is no such built-in method / class. You must write your own conversion.
You need to write a converter class for that, something like this:
public DataRow ToDataRow<T>(T entity)
public DataTable ToDataTable<T>(IEnumerable<T> entities)
I am implementing the Builder Pattern in order to generate a set of objects. These objects then have to be serialized to XML and deserialized from XML.
I know how to perform the serialization and deserialization however I am unsure how to integrate it into the design pattern.
For example suppose my code uses the builder to create products foo and bar. My first thought is to put a serialize function on each one because each product knows what to serialize.
My next thought was to put the deserialization in the Director or the ConcreteBuilder.
What I don't like about this is that the serialization and deserialization functions will be in different places - one in the file for the declaration of the foo and bar objects and the other in the files for something else. I am worried that they might end up becoming out of sync with each other as I work on the product classes.
My final thought was for the Director or ConcreteBuilder to perform the serialization and deserialization. What I don't like about that is the products then have to know which builder was used or know who the Director is.
To clarify - there are two situations where a product can be created:
User clicks on a button in the user interface
User loads a XML project
Can you not simply have a static serialize/deserialize class and create a generic method that can take any type of object? Isn't the pattern simply for building the objects? You can then serialize as you wish?
Something like:
public static string Serialize<T>(T data)
{
XmlSerializer xmlSerializer = new XmlSerializer(typeof(T));
StringWriter sw = new StringWriter();
xmlSerializer.Serialize(sw, data);
return sw.ToString();
}
My current solution is to have the Product perform the serialization and the ConcreteBuilder perform the deserialization, then put both the Product and it's ConcreteBuilder declarations into the same source file.
Although the task is spread across two classes it is at least kept together in one file.
Any better solutions are appreciated.
I'm developing a system to pick up XML attachments from emails, via Exchange Web Services, and enter them into a DB, via a custom DAL object that I've created.
I've manage to extract the XML attachment and have it ready as a stream... they question is how to parse this stream and populate a DAL object.
I can create an XMLTextReader and iterate through each element. I don't see any problems with this other than that I suspect there is a much slicker way. The reader seems to treat the opening tag, the content of the tag and the closing tag as different elements (using reader.NodeType). I expected myValue to be considered one element rather than three. Like I said, I can get round this problem, but I'm sure there must be a better way.
I came across the idea of using an XML Serializer (completely new to me) but a quick look suggested that these can't handle ArrayLists and List (I'm using List).
Again, I'm new to LINQ, but LINQ-to-XML has also been mentioned, but examples I've seen seem rather complex - though that my simply be my lack of familiarity.
Basically, I don't want a cludged system, but I don't want to use any complicated technique with a learning curve, just because it's 'cool'.
What is the simplest and most effective way of translating this XML/Stream in to my DAL objects?
XML Sample:
<?xml version="1.0" encoding="UTF-8"?>
<enquiry>
<enquiryno>100001</enquiryno>
<companyname>myco</companyname>
<typeofbusiness>dunno</typeofbusiness>
<companyregno>ABC123</companyregno>
<postcode>12345</postcode>
<contactemail>me#example.com</contactemail>
<firstname>My</firstname>
<lastname>Name</lastname>
<vehicles>
<vehicle>
<vehiclereg>54321</vehiclereg>
<vehicletype>Car</vehicletype>
<vehiclemake>Ford</vehiclemake>
<cabtype>n/a</cabtype>
<powerbhp>130</powerbhp>
<registrationdate>01/01/2003</registrationdate>
</vehicle>
</vehicles>
</enquiry>
Update 1:
I'm trying to deserialize, based on Graham's example. I think I've set up the DAL for serialization, including specifying [XmlElement("whatever")] for each property. And I've tried to deserialize using the following:
SalesEnquiry enquiry = null;
XmlSerializer serializer = new XmlSerializer(typeof(SalesEnquiry));
enquiry = (SalesEnquiry)serializer.Deserialize(stream);
However, I get an exception:'There is an error in XML document (2, 2)'. The innerexception states {"<enquiry xmlns=''> was not expected."}
Conclusion (updated):
My previous problem was the fact that the element in the XML file (Enquiry) != the name of the class (SalesEnquiry). Rather than an [XmlElement] attribute for the class, we need an [XmlRoot] attribute instead. For completeness, if you want a property in your class to be ignored during serialization, you use the [XmlIgnore] attribute.
I've successfully serialized my object, and have now successfully taken the incoming XML and de-serialized it into a SalesEnquiry object.
This approach is far easier than manually parsing the XML. OK, there has been a steep learning curve, but it was worth it.
Thanks!
If your XML uses a schema (i.e. you're always going to know what elements appear, and where they appear in the tree), you could use XmlSerializer to create your objects. You'd just need some attributes on your classes to tell the serializer what XML elements or attributes they correspond to. Then you just load up your XML, create a new XmlSerializer with the type of the .NET object you want to create, and call the Deserialize method.
For example, you have a class like this:
[Serializable]
public class Person
{
[XmlElement("PersonName")]
public string Name { get; set; }
[XmlElement("PersonAge")]
public int Age { get; set; }
[XmlArrayItem("Child")]
public List<string> Children { get; set; }
}
And input XML like this (saved in a file for this example):
<?xml version="1.0"?>
<Person>
<PersonName>Bob</PersonName>
<PersonAge>35</PersonAge>
<Children>
<Child>Chris</Child>
<Child>Alice</Child>
</Children>
</Person>
Then you create a Person instance like this:
Person person = null;
XmlSerializer serializer = new XmlSerializer(typeof(Person));
using (FileStream fs = new FileStream(GetFileName(), FileMode.Open))
{
person = (Person)serializer.Deserialize(fs);
}
Update:
Based on your last update, I would guess that either you need to specify an XmlRoot attribute on the class that's acting as your root element (i.e. SalesEnquiry), or the XmlSerializer might be a bit confused that you're referencing an empty namespace in your XML (xmlns='' doesn't seem right).
XmlSerializer does support arrays & lists... as long as the contained type is serializable.
I have found Xsd2Code very helpful for this kind of thing: http://xsd2code.codeplex.com/
Basically, all you need to do is write an xsd file (an XML schema file) and specify a few command line switches. Xsd2Code will automatically generate a C# class file that contains all the classes and properties plus everything needed to handle the serialization. It's not a perfect solution as it doesn't support all aspects of XSD, but if your XML files are relatively simple collections of elements and attributes, it should be a nice short-cut for you.
There's another similar project on Codeplex called Linq to XSD (http://linqtoxsd.codeplex.com/), which was designed to enforce the entire XSD specification, but last time I checked, it was no longer being supported and not really ready for prime time. Thought it was worth a mention, though.
If I am dealing with several standard xml formats what would be the best practice way of encapsulating them in C# 3.5? I'd like to end up with something similar to the System.ServiceModel.Syndication namespace.
A class that encapsulates the ADF 1.0 XML standard would be one example. It has the main XML root node, 6 child elements, 4 of which are required IIRC, several required and optional elements and attributes further down the tree. I'd like the class to create, at a minimum, the XML for all the required pieces all the way up to a full XML representation. (Make sense).
With LINQ 4 XML and extension classes, etc, etc, there has to be some ideas on quickly generating a class structure for use. Yes? No? :)
Am not sure if I gave enough details to get one correct answer but am willing to entertain ideas right now.
TIA
XML serialization seems a good approach. You could even use xsd.exe to generate the classes automatically...
EDIT
Note that the class names generated by the tool are usually not very convenient, so you might want to rename them. You might also want to change arrays of T to List<T>, so that you can easily add items where needed.
Assuming the class for the root element is named ADF, you can load an ADF document as follows :
ADF adf = null;
XmlSerializer xs = new XmlSerializer(typeof(ADF));
using (XmlReader reader = XmlReader.Create(fileName))
{
adf = (ADF)xs.Deserialize(reader);
}
And to save it :
ADF adf = ...; // create or modify your document
...
XmlSerializer xs = new XmlSerializer(typeof(ADF));
using (XmlWriter writer = XmlWriter.Create(fileName))
{
xs.Serialize(writer, adf);
}
Why not just follow the pattern of the SyndicationFeed object in the Syndication namespace? Create a class that takes in a Uri to the xml document or just takes in the document fragment.
Then parse the document based on your standards (this parsing can be done using LinqToXml if you wanted to, though regEx might be faster if you are comfortable with them). Throw exceptions or track errors appropriately when the document doesn't pass the specification rules.
If the document passes the parse step then break the pieces of the document out into public getter properties of your object. Then return the fully hydrated object back to the consumer for use
Seems pretty straight forward to me. Is that what you are after or are you looking for something more than this?
can anyone suggest the best way to serialize data (a class actually) to a DB?
I am using SQL server 2008 but i presume i need to serialize the class to a string / or other data type before storing in the database?
I presume that this field needs to be text or binary??
Does SQL server 2008 (or .net 3.5) support serializing directly tothe database ??
Any help really appreciated
You can xml serialize the class into an xml field. We use this all the time for exception logging in an ETL.
Using the XmlSerializer you may want a helper method somewhere which serializes the class to a string...
public static string SerializeToXml<T>(T value)
{
StringWriter writer = new StringWriter(CultureInfo.InvariantCulture);
XmlSerializer serializer = new XmlSerializer(typeof(T));
serializer.Serialize(writer, value);
return writer.ToString();
}
Then just put the string into the db like any other.
The best way to store data in a database is in columns (per property), so that it is queryable and indexable. ORM tools will help with this.
However, it is also possible to serialize a class as a CLOB/BLOB (varchar(max)/varbinary(max) etc).
It this is what you want, avoid anything implementation-specific or version-intolerant; so in particular, don't use BinaryFormatter. Anything contract-based should work; XmlSerializer, DataContractSerializer, etc. Or for fast binary, protobuf-net might be worth a look.
But I stress; columns would be better.
Without generics (better sollution)
public static string SerializeToXml(object value)
{
StringWriter writer = new StringWriter(CultureInfo.InvariantCulture);
XmlSerializer serializer = new XmlSerializer(value.GetType());
serializer.Serialize(writer, value);
return writer.ToString();
}
I've serialized objects as XML and thrown those into the database just fine. Since we knew the max amount of text we used the varchar(max) datatype instead of getting into TEXT or Binary formats.
This was a OLTP web application and one thing we found was that using a column with an xml datatype invoked some significant cpu usage as the xml was validated on every insert. In our case the xml was never queried for anything so not having the xml query capabilities worked out ok for us.
There are couple of options:
Runtime serialization, serializable objects are marked with the
Serializable attribute, in which case the IFormatter class does all the work of
serialization. A serializable object can ISerializable, but then you will
need to implement the GetObjectData( ) method. The problem with runtime serialization is that program reading the xml data needs to have
the knowledge of the CLR types.
Xml serialization: Unline runtime serialization, you will get good interoperability in this case.
The XmlSerializer type contains the methods Serialize( ) and Deserialize( ), thus
any object can be serialized to XML and saved into the database and when you retreive it back, you
can deserialize it easily.
To read data from the database, you can use the SqlCommand class
method that executes SQL queries, namely ExecuteXmlReader( ).
ExecuteXmlReader( ) returns an instance of XmlReader and that will read your xml data.
Check out Linq-to-SQL (questions on SO, resource on MSDN) or other O-R Mapping options.