High ORM Question 161 of 228

When should you use only(), defer(), and values()?

Python & Django · Speak this in 60–90 seconds · Faridabad & Delhi NCR

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ViewBusiness logic

Model + TemplateData + HTML

only() loads a subset of columns

Why interviewers care about ORM:

They are checking judgment

on ORM.

A good answer names

the situation, the default choice, and one exception - that reads as experience.

Stay structured

Name the idea, why it exists, then one short example.

Close cleanly

End with when you use it and one common pitfall.

Before you speak the answer, walk the interviewer through these steps:

1
only() loads a subset
of columns
2
defer() delays the rest
until attribute access, which can surprise you with extra queries.
3
values()/values_list() return dicts or
tuples and skip model instantiation, which is faster for read-only APIs.
4
Do not mix deferred
models with code that touches skipped fields in a loop.
5
Common mistake
What juniors usually get wrong.
6
Close
When you pick this over the alternative.

Here's a short line you can speak, broken into clear beats:

Say this line

“values()/values_list() return dicts or tuples and skip model instantiation, whic”

Break into beats

valuesvalueslistreturndictsor

Speaking order

2987408337471632900

Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.

only() loads a subset of columns defer() delays the rest until attribute access, which can surprise you with extra queries.