Sharepoint Lookup Field values

Oh I hope this post will be interesting for most of the users who wants to develop their own webparts.

Lets consider you require to display the values of lookup field for your webpart form in a dropdown.

You can use it in your dropdown datasource:
where field is SPField and list is SPList

DropDownList ddl = new DropDownList();
ddl.ID = field.Id;
ddl.DataSource = DataSource(field, list);

Here it goes :


public ICollection DataSource(SPField Colfield, SPList lookupList)
{
string lookupField;
int num = 0;
SPFieldLookup lookup = (SPFieldLookup)Colfield;
lookupList = lookupList.ParentWeb.Lists[new Guid(lookup.LookupList)];
if (lookup != null)
{
lookupField = lookup.LookupField;
if (string.IsNullOrEmpty(lookupField))
{
lookupField = "Title";
}
}
else
{
return null;
}
DataTable table = new DataTable();
table.Columns.Add(new DataColumn("ValueField", typeof(int)));
table.Columns.Add(new DataColumn("TextField", typeof(string)));
if (!lookup.Required && !lookup.AllowMultipleValues)
{
DataRow row = table.NewRow();
row[0] = 0;
row[1] = SPResource.GetString("LookupFieldNoneOption", new object[0]);
table.Rows.Add(row);
num++;
}
if (lookupList != null)
{
try
{
SPField field = lookupList.Fields.GetField(lookupField);
SPQuery query = new SPQuery();
StringBuilder builder = new StringBuilder("builder.Append(lookupField);
builder.Append("\"/>builder.Append(lookupField);
builder.Append("\"/>");
query.ViewXml = builder.ToString();
SPListItemCollection items = lookupList.GetItems(query);
for (int i = 0; i < items.Count; i++)
{
string fieldValueAsText = field.GetFieldValueAsText(items[i][lookupField]);
if (!string.IsNullOrEmpty(fieldValueAsText))
{
DataRow row2 = table.NewRow();
row2[0] = items[i].ID;
row2[1] = fieldValueAsText;
table.Rows.Add(row2);
num++;
}
}
return new DataView(table);
}
catch (ArgumentException)
{
return null;
}
}
return null;
}

Don't forget to put your comments if it helps you