Field lookups (exact, contains, gt, lt) in Django - Step-by-Step Execution

Concept Flow - Field lookups (exact, contains, gt, lt)

Start Query

↓

Choose Field Lookup

↓

Apply Filter Condition

↓

Database Filters Rows

↓

Return Filtered Results

↓

End

This flow shows how Django applies field lookups to filter database records step-by-step.

Execution Sample

Django

Book.objects.filter(title__exact='Django')
Book.objects.filter(title__contains='Django')
Book.objects.filter(pages__gt=100)
Book.objects.filter(pages__lt=50)

These queries filter books by exact title, title containing text, pages greater than, and pages less than values.

Execution Table

Step	Query	Lookup Type	Condition Evaluated	Rows Matched	Result
1	title__exact='Django'	exact	title == 'Django'	2	Returns 2 books with title exactly 'Django'
2	title__contains='Django'	contains	'Django' in title	3	Returns 3 books with 'Django' in title
3	pages__gt=100	gt	pages > 100	4	Returns 4 books with pages greater than 100
4	pages__lt=50	lt	pages < 50	1	Returns 1 book with pages less than 50
5	End	-	-	-	No more queries

💡 All queries processed and filtered results returned.

Variable Tracker

Variable	Start	After Query 1	After Query 2	After Query 3	After Query 4	Final
filtered_books	[]	[Book1, Book2]	[Book1, Book2, Book3]	[Book4, Book5, Book6, Book7]	[Book8]	Final filtered sets per query

Key Moments - 3 Insights

Why does 'title__exact' only match exact titles and not partial words?

Because 'exact' lookup checks for complete equality as shown in execution_table row 1, it does not match substrings.

How does 'contains' differ from 'exact' in filtering?

'contains' checks if the substring exists anywhere in the field, as seen in execution_table row 2, so it matches more results.

What happens if you use 'gt' or 'lt' on a non-numeric field?

Django will raise an error because 'gt' and 'lt' expect comparable numeric or date fields, not strings.

Visual Quiz - 3 Questions

Look at the execution table, how many books matched the 'pages__gt=100' query?

A 2

B 3

C 4

D 1

💡 Hint

Check the 'Rows Matched' column in row 3 of the execution_table.

At which step does the query check if the title contains 'Django'?

A Step 2

B Step 1

C Step 3

D Step 4

💡 Hint

Look for 'contains' in the 'Lookup Type' column in the execution_table.

If you change 'pages__lt=50' to 'pages__lt=150', what happens to matched rows?

A Fewer rows will match

B More rows will match

C Same number of rows match

D Query will fail

💡 Hint

Refer to how 'lt' compares values in the execution_table and variable_tracker.

Concept Snapshot

Django field lookups filter querysets by conditions.
Use __exact for exact match.
Use __contains for substring match.
Use __gt and __lt for greater or less than comparisons.
Filters return matching database rows.
Syntax: Model.objects.filter(field__lookup=value).

Full Transcript

This visual execution trace shows how Django field lookups work step-by-step. Starting a query, Django applies the chosen lookup like exact, contains, gt, or lt to filter database rows. For example, title__exact='Django' matches only titles exactly equal to 'Django'. Title__contains='Django' matches any title containing that word. Pages__gt=100 matches books with more than 100 pages. Pages__lt=50 matches books with fewer than 50 pages. The execution table tracks each query step, condition checked, rows matched, and results returned. The variable tracker shows how filtered results change after each query. Key moments clarify common confusions like exact vs contains behavior and numeric comparisons. The quiz tests understanding by referencing the execution table and variable states. This helps beginners see how Django filters data visually and clearly.