Django, query objects BEFORE certain id

Question

I have encountered one interesting problem

Lets say I have objects in my database likt this:

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Lets consider numbers as ids of these objects

If I want to get two objects after 5, I need to use this query:

MyObject.objects.filter(id__gt=5).order_by("id")[:2]

This will return to me this result:

[6, 7]

Which is right result.

Now I want to get two objects before object 5. I do this query:

MyObject.objects.filter(id__lt=5).order_by("id")[:2]

However, this returns to me this:

[1, 2] instead of [3, 4]

So I need to query objects starting from object of id=5

I know that there is ranged query, but it does not suit when working only with ids.

Is it possible to query objects before certain id starting from this object itself?

======== UPDATE ========

There is a catch, sometimes objects are also filtered by another condition and this means that id's are not correlated by their indexes:

[34, 45, 46, 66, 100, 105, 211]

How it is possible to get two objects, for example, just before 66?

Did you use 2 underscores at id_lt? Or just 1 as in your example? Because I believe it's id__lt as far I've searched. — King Reload
– King Reload, Commented Mar 15, 2018 at 14:25
@KingReload it should be id__lt but still his order is ascending — iklinac
– iklinac, Commented Mar 15, 2018 at 14:33

iklinac · Accepted Answer · 2018-03-15 14:31:12Z

3

By doing descending order

MyObject.objects.filter(id__lt=5).order_by("-id")[:2]

You will get 2 number nearest to 5

If you expect never to delete data then you can use range(between)

MyObject.objects.filter(id__range=(4, 3))

answered Mar 15, 2018 at 14:24

iklinac

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Comments

anjaneyulubatta505 · Accepted Answer · 2018-03-15 16:10:33Z

2

we can get it by using slicing & descending ordering

 obj_id = 5
 MyObject.objects.filter(id__lt=obj_id).order_by("-id")[1:3]

answered Mar 15, 2018 at 14:25

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