How to get all fields of a list using JS Client Object Model

Question

Is it possible to retrieve all fields of a list (or default view) through the JavaScript Client Object Model and filter the fields on type (e.g. I only want the Choice fields).

    var clientContext = new SP.ClientContext.get_current();
    var web = clientContext.get_web();
    var list = web.get_lists().getByTitle(listName);
    var defaultview = list.getView('00000000-0000-0000-0000-000000000000');
    this.listFields = defaultview.get_viewFields();
    clientContext.executeQueryAsync(Function.createDelegate(this, 
        this.onListFieldsQuerySucceeded), Function.createDelegate(this, 
        this.onListFieldsQueryFailed));

    function onListFieldsQuerySucceeded() {
        var fieldEnumerator = listFields.getEnumerator();
        while (fieldEnumerator.moveNext()) {
            var oField = fieldEnumerator.get_current();
            ...
        }
    }

Right now I'm getting following exception on listFields.getEnumerator()

Microsoft JScript runtime error: The collection has not been initialized. It has not been requested or the request has not been executed. It may need to be explicitly requested.

Same problem if I get the fields on the list directly.

Answer 1

You missed this line: clientContext.load(this.listFields); right after this.listFields = defaultview.get_viewFields(); , because your code not actually loads fields.

Complete code with field type checking looks like this one:

var clientContext = new SP.ClientContext.get_current();
    var web = clientContext.get_web();
    var list = web.get_lists().getByTitle(listName);
    this.listFields = list.get_fields();
    clientContext.load(this.listFields);
    clientContext.executeQueryAsync(Function.createDelegate(this, 
        this.onListFieldsQuerySucceeded), Function.createDelegate(this, 
        this.onListFieldsQueryFailed));

    function onListFieldsQuerySucceeded() {
        var fieldEnumerator = listFields.getEnumerator();
        while (fieldEnumerator.moveNext()) {
            var oField = fieldEnumerator.get_current();
            var fType = oField.get_fieldTypeKind();
            if(fType === SP.FieldType.choice) {
               .....
            }
        }
    }  

To verify field type you can use get_fieldTypeKind() or typeAsString() methods.