C# - XML deserialization - ignore elements with attribue

Question

I need to deserialize some xml to c# objects. This is my class:

[XmlRoot("root")]
[Serializable]
public class MyRoot
{        
    [XmlElement("category")]
    public List<Category> Categories { get; set; }
}

I'm deserializing like this:

root = (MyRoot)new XmlSerializer(typeof(MyRoot)).Deserialize(new StringReader(client.DownloadString(XmlUrl)));

But I want to ignore some Category elements with specified "id" attribute values. Is there some way I can do this?

Simply post-process deserialized object (go through list, check id and remove). If you can't do that, then please explain why. — Sinatr, Mar 08 '16 at 14:35
Is this a one way street or do you need to deserialize the XML later on? — user1859022, Mar 08 '16 at 14:45

score 2 · Answer 1 · answered Mar 08 '16 at 14:40

Another approach is to have a property named something like ImportCategories with the [XmlElement("category")] attribute and then have Categories as a property that returns a filtered list from ImportCategories using LINQ.

Then your code would do the deserialisaion and then use root.Categories.

Dan Field · Accepted Answer · 2016-03-08T14:51:03.457

2

Implementing IXmlSerializable is one way to go, but perhaps an easier path would be simply modifying the XML (using LINQ or XSLT?) ahead of time:

HashSet<string> badIds = new HashSet<string>();
badIds.Add("1");
badIds.Add("excludeme");
XDocument xd = XDocument.Load(new StringReader(client.DownloadString(XmlUrl)));
var badCategories = xd.Root.Descendants("category").Where(x => badIds.Contains((string)x.Attribute("id")));
if (badCategories != null && badCategories.Any())
  badCategories.Remove();
MyRoot root = (MyRoot)new XmlSerializer(typeof(MyRoot)).Deserialize(xd.Root.CreateReader());

You could do something similar on your resulting collection, but it's entirely possible you don't serialize the id, and may not want to/need to otherwise.

edited Mar 08 '16 at 14:51

answered Mar 08 '16 at 14:41

Dan Field

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Thanks! I was just wondering, if there is some c# attribute to do this – petros Mar 08 '16 at 14:45
Nope. Not without custom `IXmlSerializable` – Dan Field Mar 08 '16 at 14:48

score 1 · Answer 3 · answered Mar 08 '16 at 14:37

To do this the Microsoft way, you would need to implement an IXmlSerializable interface for the class that you want to serialize:

https://msdn.microsoft.com/en-us/library/system.xml.serialization.ixmlserializable(v=vs.110).aspx

It's going to require some hand-coding on your part - you basically have to implement the WriteXml and ReadXml methods, and you get a XmlWriter and a XmlReader interface respectively, to do what you need to do.

Just remember to keep your classes pretty atomic, so that you don't end up custom-serializing for the entire object graph (ugh).

C# - XML deserialization - ignore elements with attribue

3 Answers3