[Answered ]-Does acccessing nested FK relation's field value downgrade performance?

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You can inspect the query by printing:

print(queryset.query)

In that case Django will print the query that it will make. In this case, the query will look like:

SELECT query.campaign_name, price_sheet.id, query.campaign_status,
       query.lead_id, lead.legal_name, lead.brand_name,
       lead.working_capital, lead.payment_terms
FROM price_sheet
LEFT OUTER JOIN query ON query.id = price_sheet.query_id
LEFT OUTER JOIN lead ON lead.id = query.lead_id
WHERE price_sheet.id = pricesheet_id

Django will thus make JOINs on the models referenced by the query and by the lead of the query. Using .select_related(…) [Django-doc] to force a JOIN is not necessary in this case.

Usually it is better not to work with .values(…) [Django-doc] when you want to convert data to a JSON blob, since it erodes the logical layer that the model(s) provide. For a field with choices for example, you can no longer (easily) access the display name, etc.

👤willeM_ Van Onsem

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