High DRF Question 175 of 228

In what order does DRF run serializer validation?

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

PICTURE THIS: DJANGO MVT

URLRoute request

ViewBusiness logic

Model + TemplateData + HTML

Simple meaning

to_internal_value runs field-level to_internal_value, then field validators, then validate_<field>, then serializer.validate.

WHY — DRF instead of guessing?

Why interviewers care about DRF:

DRF questions separate people

who only read docs from people who shipped.

Keep it short, concrete,

and tied to Python work.

Stay structured

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

Close cleanly

End with when you use it and one common pitfall.

STEPS — What happens step by step?

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

1
to_internal_value runs field-level to_internal_value,
then field validators, then validate_<field>, then serializer.validate.
2
UniqueValidator and UniqueTogetherValidator run
as serializer-level validators.
3
Overriding create() does not
replace this pipeline
4
invalid data never reaches
save() if is_valid() is used correctly.
5
Common mistake
What juniors usually get wrong.
6
Close
When you pick this over the alternative.

EXAMPLE — See it in action

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

Say this line

“UniqueValidator and UniqueTogetherValidator run as serializer-level validators.”

Break into beats

UniqueValidatorandUniqueTogetherValidatorrunasserializer

Speaking order

2987408337471632900

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

Key takeaway

to_internal_value runs field-level to_internal_value, then field validators, then validate_<field>, then serializer.validate. UniqueValidator and UniqueTogetherValidator run as serializer-level validators.