[Answer]-Django pagination error with views & template

OK I managed to get it to work by changing my Views.py:

def entry(request, projects_id=1, entries_id=1):
    current_entry = Entries.objects.get(project_id=projects_id, entry_unique=entries_id)
    current_entry_unique = current_entry.entry_unique
    entry_previous = current_entry_unique
    entry_previous -= 1
    if Entries.objects.filter(project_id=projects_id, entry_unique=entry_previous).exists():
        prev_entry = Entries.objects.get(project_id=projects_id, entry_unique=entry_previous)
    else:
        prev_entry = None
    entry_next = current_entry.entry_unique
    entry_next += 1
    if Entries.objects.filter(project_id=projects_id, entry_unique=entry_next).exists():
        next_entry = Entries.objects.get(project_id=projects_id, entry_unique=entry_next)
    else:
        next_entry = None
    return render_to_response('entry.html',
                                {'projects': Projects.objects.get(id=projects_id),
                                'entry': Entries.objects.get(project_id=projects_id, entry_unique=entries_id),
                                'prev_entry': prev_entry,
                                'next_entry': next_entry }
                                )

And then my entry.html looks like this:

{% if prev_entry %}
<a href="/projects/get/{{projects.id}}/entries/get/{{entry.entry_unique|add:"-1"}}"><img src="/static/assets/img/arrow_left.png" width="40"></a>
{% endif %}
{% if next_entry %}
<a href="/projects/get/{{projects.id}}/entries/get/{{entry.entry_unique|add:"1"}}"><img src="/static/assets/img/arrow_right.png" width="40"></a>
{% endif %}

It may not be pretty but it is doing what I want it to do. There may be ways to get it to work more nicely, though.

Without Paginator:

def entry(request, projects_id, entries_id):

    entries_in_project = Entries.objects.filter(project_id=projects_id)
    entry = get_object_or_404(entries_in_project, entry_unique=entries_id)
    try:
        prev_entry_id = entries_in_project.filter(entry_unique__lt=entries_id)
            .order_by('-entry_unique').values('entry_unique')[:1][0]['entry_unique']
    except IndexError:
        prev_entry_id = None
    try:
        next_entry_id = entries_in_project.filter(entry_unique__gt=entries_id)
            .order_by('entry_unique').values('entry_unique')[:1][0]['entry_unique']
    except IndexError:
        next_entry_id = None

    return render_to_response('entry.html',{
        'projects': Projects.objects.get(id=projects_id), 'entry': entry,
        'next_entry_id': next_entry_id, 'prev_entry_id': prev_entry_id,
    })

A Better Way:

All of this could be replaced with built-in functionality:

https://docs.djangoproject.com/en/dev/ref/models/options/#order-with-respect-to

class Entries(models.Model):
    project_id = models.ForeignKey(Projects)
    entry_pubdate = models.DateTimeField('date published')

    class Meta:
        order_with_respect_to = 'project_id'

def entry(request, projects_id, entries_id):

    entry = get_object_or_404(Entries,project_id=projects_id, id=entries_id)

    next_entry = entry.get_next_in_order()
    prev_entry = entry.get_previous_in_order()

    return render_to_response('entry.html',{
        'projects': Projects.objects.get(id=projects_id), 'entry': entry,
        'next_entry': next_entry, 'prev_entry': prev_entry,
    })

In entry.html:

{% if next_entry %}<a href="{{ next_entry.get_absolute_url }}">Next</a>{% endif %}
{% if prev_entry %}<a href="{{ prev_entry.get_absolute_url }}">Previous</a>{% endif %}