I currently load an XML file into a list objects using code like this
XDocument xmlDoc = XDocument.Load(path);
List<ImportDefinition> importDefinitions = xmlDoc.Descendants("Root").Select(xElem => (ImportDefinition)xElem).ToList();
return importDefinitions;
This list of objects contains nested objects and each one has an operator for parsing the XML into the correct form like this
public static explicit operator Rules(XElement xElem)
{
try
{
return new Rules()
{
FileNameRegEx = (string)xElem.Element("FileNameRegEx"),
FileExtension = (string)xElem.Element("FileExtension")
};
}
catch (Exception ex)
{
return null;
}
This works fine for loading the XML. I now want to save this list of objects back to XML after some edits have been made.
I was hoping something like this would work
XElement xml = new XElement("Root",
from p in ObjectList
select new XElement("File",RootObject
));
}
xml.Save("C:\\temp\\newimport.xml");
However this just seems to output this
<?xml version="1.0" encoding="utf-8"?>
<Root>
<File>MyNamespace.RootObject</File>
<File>MyNamespace.RootObject</File>
</Root>
It looks like its not using the custom operators it uses when loading the files to work out the format to save in. Whats the best way to save this data back to XML to the same format it was in when I read it?
Well for one thing you've only shown us the operator for parsing from an XElement... but even so, you're obviously explicitly calling that in your LINQ expression. If you want the equivalent when building XML, you'll need to be explicit there too:
XElement xml = new XElement("Root",
from p in ObjectList
select new XElement("File", (XElement) p));
Personally I'd use methods instead of operators - ToXElement() and FromXElement() - I think it's clearer that way. ToXElement would be an instance method; FromXElement would be a static method. This is a pattern I've used many times, and it's always worked fine.
Related
Is it possible to add literal XML data within a C# code file? I'm currently using a multiline string literal but it gets messy as you can see. Any better way of doing this?
string XML = #"<?xml version=""1.0"" encoding=""utf-8""?>
<customUI xmlns=""http://schemas.example.com/customui"">
<toolbar id=""save"">
</toolbar>
</customUI>";
XML literals are a feature of VB.NET, not C#.
What you have posted is as close as you can get in C#.
You may want to consider replacing the embedded double quotes with single quotes though (as both types are valid XML).
For larger amounts of XML you may want to consider the answer from Marc - using an XML file (loaded once and stored in memory), so you can take advantage of the XML editor.
If the XML is big enough to get in the way, consider using a flat .xml file instead, either loaded from disk, or embedded as a resource. As long as you only load it once (perhaps in a static constructor) this will make no difference to performance. It will be considerably easier to maintain, as it will use the IDE's XML file editor. And it won't get in the way of your code.
With reference to my comment, I couldn't recall where I saw this, but I finally found the XmlBuilder link.
In retrospect, it seems Linq to XML would be your best bet. It's cleaner, faster and more maintainable than concatenating XML strings:
XNamespace ns = "http://schemas.example.com/customui";
XDocument doc = new XDocument(
new XDeclaration("1.0", "utf-8", "yes"),
new XElement(ns + "customUI",
new XElement(ns + "taskbar",
new XAttribute("id", "save"))
)
);
var stringWriter = new StringWriter();
doc.Save(stringWriter); //Write to StringWriter, preserving the declaration (<?xml version="1.0" encoding="utf-16" standalone="yes"?>)
var xmlString = stringWriter.ToString(); //Save as string
doc.Save(#"d:\out.xml"); //Save to file
As a peculiar, and very case-specific solution, if you happen to be working in an ASP.NET environment using the Razor engine, in a CSHTML file you can:
Func<MyType, HelperResult> xml = #<root>
<item>#(item.PropertyA)</item>
<item>#(item.PropertyB)</item>
<item>#(item.PropertyC)</item>
</root>;
With the addition of an extension method:
public static XDocument ToXDocument<T>(this Func<T, HelperResult> source, T item)
{
return XDocument.Parse(source(item).ToHtmlString());
}
You can then:
XDocument document = xml.ToXDocument(new MyType() {
PropertyA = "foo",
PropertyB = "bar",
PropertyC = "qux",
});
Again, peculiar? Yes. Case-specific? Yes. But it works, and gives great Intellisense. (mind you, it also will give a bunch of validity warnings, depending on the document validation version)
The closest we could have in C# would be through LINQ, something like that:
var xml = XDocument.Load(
new StringReader(#"<Books>
<Book author='Dan Brown'>The Da Vinci Code</Book>
<Book author='Dan Brown'>The Lost Symbol</Book>
</Books>"));
var query = from book in xml.Elements("Books").Elements("Book")
where book.Attribute("author").Value == "Dan Brown"
select book.Value;
foreach (var item in query) Console.WriteLine(item);
I am trying to parse XML document like this:
<root>
<first>1</first>
<second>2</second>
</root>
To structure like this:
class SomeClass
{
...
public string First;
public string Second;
}
but as far as I understood, I can create new object only in select statement, which only can be applied to collection and root element is not a collection.
Of course, I can select fields separately like:
new SomeClass(doc.Element("first").Value, doc.Element("second").Value);
But I'm really interested if is it possible to do it in one LINQ statement (using doc variable only once and creating object inside the LINQ statement)?
In other words: is it possible to create an object not in Select() method?
The root element may not be a collection, but when you parse the xml, your doc variable is a collection of elements, including root element. So you can still use Select:
string xml = #"<root><first>1</first><second>2</second></root>";
var doc = XDocument.Parse(xml);
var collectionOfSomeClass = doc.Elements()
.Select(x => new SomeClass
{ First = x.Element("first").Value,
Second = x.Element("second").Value
});
To start, I am constrained to .NET 2.0 so LINQ is not an option for me (though I would be curious to see a LINQ solution as fodder for pushing to move to .NET 3.5 for the project if it is easy).
I have an XSD that is turned into a set of C# classes via xsd.exe at build time. At runtime, an XML file is loaded and deserialized into the C# classes (validation occurs at this time). I need to then turn that in-memory configuration object (including the default values that were populated during import of the XML file) into a dictionary of key value pairs.
I would like the dictionary key to be a dot separated path to the value. Attribute values and element text would be considered values, everything else along the way a key into that.
As an example, imagine the following XML file:
<rootNode>
<foo enabled="true"/>
<bar enabled="false" myAttribute="5.6">
<baz>Some Text</baz>
<baz>Some other text.</baz>
</bar>
</rootNode>
would turn into a dictionary with keys like:
"rootNode.foo.enabled" = (Boolean)true
"rootNode.bar.enabled" = (Boolean)false
"rootNode.bar.myAttribute" = (Float)5.6
"rootNode.bar.baz" = List<String> { "Some Text", "Some other text." }
Things of note are that rootNode is left off not because it is special but because it had no text or attributes. Also, the dictionary is a dictionary of objects which are typed appropriately (this is already done in deserialization, which is one of the reasons I would like to work with the C# object rather than the XML directly).
Interestingly, the objects created by xsd.exe are already really close to the form I want. The class names are things like rootNodeFoo with a float field on it called myAttribute.
One of the things I have considered but am not sure how to go about are using reflection to iterate over the object tree and using the names of the classes of each object to figure out the name of the node (I may have to tweak the casing a bit). The problem with this is that it feels like the wrong solution since I already have access to a deserializer that should be able to do all of that for me and much faster.
Another option would be using XSLT to serialize the data directly to a format that is how I want. The problem here is that my XSLT knowledge is limited and I believe (correct me if I am wrong) I will lose typing on the way (everything will be a string) so I will have to essentially deserialize once again by hand to get the types back out (and this time without XSD validation that I get when I use the .NET deserializer).
In case it matters, the calls I am using to get the configuration object populated from an XML file is something like this:
var rootNode = new XmlRootAttribute();
rootNode.ElementName = "rootNode";
rootNode.Namespace = "urn:myNamespace";
var serializer = new XmlSerializer(typeof(rootNode), rootNode);
using (var reader = new StringReader(xmlString))
{
var deserializedObject = (rootNode)serializer.Deserialize(reader);
}
First observation: using the object graph is not the best place to start to generate a dot representation. You're talking about nodes which have names and are in a well-defined hierarchy and you want to produce some kind of dot notation from it; the xml DOM seems to be the best place to do this.
There are a few problems with the way you describe the problem.
The first is in the strategy when it comes to handling multiple elements of the same name. You've dodged the problem in your example by making that dictionary value actually a list, but suppose your xml looked like this:
<rootNode>
<foo enabled="true">
<bar enabled="false" myAttribute="5.6" />
<bar enabled="true" myAttribute="3.4" />
</foo>
</rootNode>
Besides foo.enabled = (Boolean)true which should be fairly obvious, what dictionary keys do you propose for the two myAttribute leaves? Or would you have a single entry, foo.bar.myAttribute = List<float> {5.6, 3.4}? So, problem #1, there's no unambiguous way to deal with multiple similarly-named non-leaf nodes.
The second problem is in selecting a data type to do the final conversion at leaf nodes (i.e. attribute or element values). If you're writing to a Dictionary<string, object>, you will probably want to select a type based on the Schema simple type of the element/attribute being read. I don't know how to do that, but suggest looking up the various uses of the System.Convert class.
Assuming for the moment that problem #1 won't surface, and that you're ok with a Dictionary<string, string> implementation, here's some code to get you started:
static void Main(string[] args)
{
var xml = #"
<rootNode>
<foo enabled=""true"">
<bar enabled=""false"" myAttribute=""5.6"" />
<baz>Text!</baz>
</foo>
</rootNode>
";
var document = new XmlDocument();
document.LoadXml(xml);
var retVal = new Dictionary<string, string>();
Go(retVal, document.DocumentElement, new List<string>());
}
private static void Go(Dictionary<string, string> theDict, XmlElement start, List<string> keyTokens)
{
// Process simple content
var textNode = start.ChildNodes.OfType<XmlText>().SingleOrDefault();
if (textNode != null)
{
theDict[string.Join(".", keyTokens.ToArray())] = textNode.Value;
}
// Process attributes
foreach (XmlAttribute att in start.Attributes)
{
theDict[string.Join(".", keyTokens.ToArray()) + "." + att.Name] = att.Value;
}
// Process child nodes
foreach (var childNode in start.ChildNodes.OfType<XmlElement>())
{
Go(theDict, childNode, new List<string>(keyTokens) { childNode.Name }); // shorthand for .Add
}
}
And here's the result:
One approach would be to implement a customer formatter and slot it into the standard serialization pattern, create a class that implements IFormatter i.e. MyDotFormatter
http://msdn.microsoft.com/en-us/library/system.runtime.serialization.iformatter.aspx
then implement as below
Stream stream = File.Open(filename, FileMode.Create);
MyDotFormatter dotFormatter = new MyDotFormatter();
Console.WriteLine("Writing Object Information");
try
{
dotFormatter.Serialize(stream, objectToSerialize);
}
catch (SerializationException ex)
{
Console.WriteLine("Exception for Serialization data : " + ex.Message);
throw;
}
finally
{
stream.Close();
Console.WriteLine("successfully wrote object information");
}
I've got an XML file which I use to create objects, change the objects, then save the objects back into the XML file.
What do I have to change in the following code so that it extracts a node from the XML based on the id, replaces that node with the new one, and saves it back into the XML?
The following gives me 'System.Xml.Linq.XElement' does not contain a constructor that takes '0' arguments':
//GET ALL SMARTFORMS AS XML
XDocument xmlDoc = null;
try
{
xmlDoc = XDocument.Load(FullXmlDataStorePathAndFileName);
}
catch (Exception ex)
{
HandleXmlFileNotFound(ex);
}
//EXTRACT THE NODE THAT NEEDS TO BE REPLACED
XElement oldElementToOverwrite = xmlDoc.Descendants("smartForm")
.Where(sf => (int)sf.Element("id") == 2)
.Select(sf => new XElement());
//CREATE THE NODE THAT WILL REPLACE IT
XElement newElementToSave = new XElement("smartForm",
new XElement("id", this.Id),
new XElement("idCode", this.IdCode),
new XElement("title", this.Title)
);
//OVERWRITE OLD WITH NEW
oldElementToOverwrite.ReplaceWith(newElementToSave);
//SAVE XML BACK TO FILE
xmlDoc.Save(FullXmlDataStorePathAndFileName);
XML file:
<?xml version="1.0" encoding="utf-8" ?>
<root>
<smartForm>
<id>1</id>
<whenCreated>2008-12-31</whenCreated>
<itemOwner>system</itemOwner>
<publishStatus>published</publishStatus>
<correctionOfId>0</correctionOfId>
<idCode>customerSpecial</idCode>
<title>Edit Customer Special</title>
<description>This form has a special setup.</description>
<labelWidth>200</labelWidth>
</smartForm>
<smartForm>
<id>2</id>
<whenCreated>2008-12-31</whenCreated>
<itemOwner>system</itemOwner>
<publishStatus>published</publishStatus>
<correctionOfId>0</correctionOfId>
<idCode>customersMain</idCode>
<title>Edit Customer</title>
<description>This form allows you to edit a customer.</description>
<labelWidth>100</labelWidth>
</smartForm>
<smartForm>
<id>3</id>
<whenCreated>2008-12-31</whenCreated>
<itemOwner>system</itemOwner>
<publishStatus>published</publishStatus>
<correctionOfId>0</correctionOfId>
<idCode>customersNameOnly</idCode>
<title>Edit Customer Name</title>
<description>This form allows you to edit a customer's name only.</description>
<labelWidth>100</labelWidth>
</smartForm>
</root>
Well, the error has nothing to do with saving, or even with replacement - it has to do with you trying to create an XElement without specifying the name. Why are you trying to use Select at all? My guess is you just want to use Single:
XElement oldElementToOverwrite = xmlDoc.Descendants("smartForm")
.Where(sf => (int)sf.Element("id") == 2)
.Single();
(As Noldorin notes, you can give Single a predicate to avoid using Where at all. Personally I quite like to split the two operations up, but they'll be semantically equivalent.)
That will return the single element in the sequence, or throw an exception if there are 0 elements or more than one. Alternatives are to use SingleOrDefault, First, or FirstOrDefault:
SingleOrDefault if it's legal to have 0 or 1
First if it's legal to have 1 or more
FirstOrDefault if it's legal to have 0 or more
If you're using an "OrDefault" one, the result will be null if there are no matches.
I think the problem is simply your use of the Select call in the statement assigning oldElementToOverwrite. You actually seem to want the Single extension method.
XElement oldElementToOverwrite = xmlDoc.Descendants("smartForm")
.Single(sf => (int)sf.Element("id") == 2)
I want to convert an XML document containing many elements within a node (around 150) into another XML document with a slightly different schema but mostly with the same element names. Now do I have to manually map each element/node between the 2 documents. For that I will have to hardcode 150 lines of mapping and element names. Something like this:
XElement newOrder = new XElement("Order");
newOrder.Add(new XElement("OrderId", (string)oldOrder.Element("OrderId")),
newOrder.Add(new XElement("OrderName", (string)oldOrder.Element("OrderName")),
...............
...............
...............and so on
The newOrder document may contain additional nodes which will be set to null if nothing is found for them in the oldOrder. So do I have any other choice than to hardcode 150 element names like orderId, orderName and so on... Or is there some better more maintainable way?
Use an XSLT transform instead. You can use the built-in .NET XslCompiledTransform to do the transformation. Saves you from having to type out stacks of code. If you don't already know XSL/XSLT, then learning it is something that'll bank you CV :)
Good luck!
Use an XSLT transformation to translate your old xml document into the new format.
XElement.Add has an overload that takes object[].
List<string> elementNames = GetElementNames();
newOrder.Add(
elementNames
.Select(name => GetElement(name, oldOrder))
.Where(element => element != null)
.ToArray()
);
//
public XElement GetElement(string name, XElement source)
{
XElement result = null;
XElement original = source.Elements(name).FirstOrDefault();
if (original != null)
{
result = new XElement(name, (string)original)
}
return result;
}