Include all non-system fields for listItems from client-side

Question

Usually for retrieve information from list without system fields we've use code like this:

clientContext.Load(logWorkItems,
  items => items.Include(
   item => item["Hours_x0020_spent"],
   item => item["Issue"],
   item => item["Date"]));

but now I have a lot of lists and I think its not good to write for each list it's own included fields one by one. Maybe it would be better to write flexible code for any list, but each of my ideas is't work.

Before loading collection of list items I'm loading list by title:

var list = context.Web.Lists.GetByTitle(listTitle);
context.Load(list);
context.ExecuteQuery();

May be there is a way to use collection list.Fields for retrieving all field titles to some List<string>, exclude from this list all of the system fields titles, and after that do some magic and include each non-system title to context.Load method?

Thank you in advance

Answer 1

I've solved this problem by creating an array of expressions that I will include:

public static Expression<Func<ListItem, object>>[] ExcludeSystemFieldsExpressions(FieldCollection fields)
{
    var expressionsList = new List<Expression<Func<ListItem, object>>>();

    foreach (var item in fields)
    {
        var internalName = item.InternalName;
        if(!systemFieldsTitles.Contains(internalName))
            expressionsList.Add(x => x[internalName]);
    }
    return expressionsList.ToArray();
}

and whole code that will retrieve all fields without system fields:

var list = context.Web.Lists.GetByTitle(listTitle);
var fields = list.Fields;
context.Load(list);
context.Load(fields);
context.ExecuteQuery();

var listItems = list.GetItems(new CamlQuery { ViewXml = camlQuery });
var expressions = ExcludeSystemFieldsExpressions(fields);
context.Load(listItems, items => items.Include(expressions));
context.ExecuteQuery();

As Danny Engelman mentioned before this process doesn't affect perfomance, but when you will get your collection there won't be any of system fields, so it will be easier to manage this list for other developers and manipulate only data that we need, excluding other one.

P.S. systemFieldsTitles it's a List<string> that includes internal names of system fields, I've published source code of this list here: https://gist.github.com/reslea/564552907fca514ce61d

Answer 2

var systemFieldsIds = typeof(SPBuiltInFieldId).GetFields().Select(it => (Guid)it.GetValue(null)).ToArray();
var non_system_fields = list.Fields.Cast<SPField>().Where(it => systemFieldsIds.Contains(it.Id) == false).ToArray();