Error when trying to get single item from element.all in Protractor - protractor

Question

I have the following test code (a simplified example):
e = element(by.id('element-id'));
it('description', function(){
e.all(by.tagName('my-directive')).then(function(items){
expect(items.count()).toEqual(3); //error
expect(items.length).toEqual(3); //ok
expect(items.get(0).getAttribute('my-attr')).toEqual('1'); //error
});
});
This is the HTML:
<div id="element-id">
<my-directive my-attr="1"></my-directive>
<my-directive my-attr="0"></my-directive>
<my-directive my-attr="0"></my-directive>
</div>
When I run this test I get the following error:
TypeError: undefined is not a function
I stripped it down and found out that the error is from the get() function and the count() function. I have read about the functions in the Protractor API and used them the same way as the example on the site, so I don't understand why it does not work for me.
Does anyone know what I'm doing wrong?
I have also tried this (included 'element'):
e.element.all(by.tagName('my-directive')).then(function(items){...})
But that gave an error event without the get() function.

Answer 1

items in this case is just an ordinary array. You get
TypeError: undefined is not a function
because there isn't any function on the Array.prototype called count.
count() and get() can only be called on ElementFinderArrays, which is a Protractor specific object: http://angular.github.io/protractor/#/api?view=ElementArrayFinder
If you want to get the length and one of the elements' attribute, this will work:
e.all(by.tagName('my-directive')).then(function(items){
expect(items.length).toEqual(3);
expect(items[0].getAttribute('my-attr')).toEqual('1');
});
or like this:
expect(e.all(by.tagName('my-directive')).count()).toEqual(3);
expect(e.all(by.tagName('my-directive')).get(0).getAttribute('my-attr')).toEqual(1);