C# XmlSerializer conditionally serialialize List<T> items

Question

i need to serialize and deserialize XML with C# XmlSerializer (or is there something better?).

[XmlElement]
public virtual List<Map> Maps { get; set; }

public class Map
{
    [XmlAttribute("item")]
    public string Item { get; set; }

    [XmlAttribute("uri")]
    public string Uri { get; set; }
}

Maps = new List<Map>{
    new Map { Item="", Uri="" },
    new Map { Item="something", Uri="foo" },
    new Map { Item="", Uri="foo" },
}

The serializer should throw out every item with string.IsNullOrEmpty(map.Item) so that the resulting Xml only holds the map with "something". How can I achieve this without a big hassle?:

<Maps> <Map item="something" uri="foo" /> </Maps>

Answer 1

好吧，您可以尝试创建XmlWriter，该过滤器过滤掉所有带有xsi：nil属性或包含空字符串的元素，并将所有其他调用传递给基础标准XmlWriter，以“清理”序列化的XML。

Answer 2

As far as I've understood, you want to filter your XML before you serialize it.

I suggest you use LINQ for this:

var filteredMaps = Maps.Where(map => !string.IsNullOrWhiteSpace(map.Item)).ToList();

Notice the .ToList() call at the end of the line. This is important, as your XmlSerializer is of type List<Map> I suppose. Put this line before you serialize your object and the result should look like this:

<?xml version="1.0" encoding="utf-8"?>
<ArrayOfMap xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Map item="something" uri="foo" />
</ArrayOfMap>

Don't forget the using System.Linq;