For what reasons can a query in mongodb like db.presets.find({}, {"name":1}) not work?

Question

MongoDB

Good afternoon.
On my PC, I created a selection from the mongo base, which should select the names of all fields in the presets collection.
Everything works correctly on the PC, but when uploaded to 2 different servers, nothing works =(
Through trial / error / tests, I came to the conclusion that the line does not work:

presets_names1 = db.presets.find({}, {"name":1})
args['presets_names1'] = presets_names1

Since in the django template, this code does not output anything:

{% for pres1 in presets_names1 %}
<label class="radio">
<input class="pres1" type="radio" name="group1" value="{{ pres1.name }}">{{ pres1.name }}
</label>
{% endfor %}

The fact is that other requests from this collection work and are displayed in the template..

pres = presets_col.find_one({'name':preset})
preset_username = pres['login']

There may be a mistake in a small detail, but I have been unable to find it for more than 5 hours. So the question arose, maybe someone came across, for what reasons the query db.presets.find({}, {"name":1}) might not work?
Again, everything works on my PC. on the PC and two servers have the same bases. Versions of mongodb 3. Django: 1.8.1 on the PC and one server, and the second 1.7.7.
I will be grateful for any help. =)

Answer 1

db.presets.find - returns an iterator, i.e. the data can be "read" once, perhaps you "subtracted" it before the template. Try turning it into an array right away (for small lists):

presets_names1 = list(db.presets.find({}, {"name":1}))