Add a new Field to a SharePoint List with XML

Question

i had create a list programmatically on Feature_activated. Now i want to add a new Field to my list with an XML File on UpgradeActions from the Feature. I know the solution for add a Field with C#.

regards

gidion

Answer 1

I implemented similar behavior some time ago, I used xml file with following structure:

<?xml version="1.0" encoding="utf-8" ?>
<Fields ListUrl="Lists/Test">
 <Add>
  <Field ID="{1174073D-CD08-4A8A-A70E-5199200E04AC}" 
         Name="TestField"  
         Required="TRUE" 
         Indexed="TRUE" 
         MaxLength="255" 
         Type="Text" 
         DisplayName="TestField" />
 </Add>
</Fields>

To deserialize xml file I used following class:

[Serializable]
[XmlRoot("Fields")]
public class FieldsConfiguration
{
    [XmlAttribute]
    public string ListUrl { get; set; }

    [XmlArrayItem(typeof(Field))]
    public List<Field> Add { get; set; }
}

public class Field
{
    [XmlAttribute]
    public string ID { get; set; }

    [XmlAttribute]
    public string Name { get; set; }

    [XmlAttribute]
    public string Type { get; set; }

    [XmlAttribute]
    public string List { get; set; }
 }

I added xml file to feature definition. To get xml file name in my feature receiver I used code:

string fileName = Path.Combine(properties.Definition.RootDirectory, "FileName.xml");

Method that applies changes to list:

    /// <summary>
    /// Method adds fields to list from xml file.
    /// </summary>
    /// <param name="config">Deserialized xml file</param>
    /// <param name="doc">XmlDocument of xml file</param>
    /// <param name="web">Current web</param>
    /// <param name="list">Current list</param>
    protected void AddFieldsFromFile(FieldsConfiguration config, XmlDocument doc, SPWeb web, SPList list)
    {
        foreach (var field in config.Add)
        {
            //check if field is already exist
            if (list.Fields.ContainsField(field.Name))
                continue;
            //get field schema from xml
            var fieldSchema = doc.SelectSingleNode(string.Format("/Fields/Add/Field[@Name='{0}']", field.Name));
            if (fieldSchema == null || fieldSchema.Attributes == null)
                continue;
            //hack for Lookup fields
            if(!string.IsNullOrEmpty(field.List))
            {
                var lookupList = web.GetListNoThrow(field.List);
                if (lookupList == null)
                    continue;

                fieldSchema.Attributes["List"].Value = lookupList.ID.ToString();
            }
            list.Fields.AddFieldAsXml(fieldSchema.OuterXml, false, SPAddFieldOptions.AddFieldInternalNameHint);
            list.Update();
        }
    }

Provided code supports all field types except Taxonomy fields.