Folder structure patterns in FastAPI - Step-by-Step Execution

Concept Flow - Folder structure patterns

Start Project

↓

Create main.py

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Add folders: app/, tests/

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Inside app/: create subfolders

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app/api/ -> routes

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app/models/ -> data models

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app/schemas/ -> data validation

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app/core/ -> config, security

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app/db/ -> database connection

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tests/ -> test files

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Run FastAPI server

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Project organized and ready

This flow shows how a FastAPI project is organized step-by-step into folders for routes, models, schemas, core logic, database, and tests.

Execution Sample

FastAPI

app/
  api/
    v1.py
  models/
    user.py
  schemas/
    user.py
  core/
    config.py
  db/
    session.py
main.py

This folder structure organizes FastAPI code by responsibility: api for routes, models for data models, schemas for validation, core for config, db for database, and main.py to start the app.

Execution Table

Step	Action	Folder/File Created	Purpose	Notes
1	Create project root	project_root/	Base folder	Starting point
2	Create main app folder	app/	Holds app code	Main source folder
3	Create api folder	app/api/	Store route files	Organizes endpoints
4	Create models folder	app/models/	Define data models	Database models here
5	Create schemas folder	app/schemas/	Define data validation	Pydantic schemas
6	Create core folder	app/core/	Config and security	Settings and auth
7	Create db folder	app/db/	Database connection	Session and engine
8	Create tests folder	tests/	Test files	Separate from app code
9	Create main.py	main.py	Start FastAPI app	Entry point
10	Run server	N/A	Start app	App ready to serve requests
11	Exit	N/A	Setup complete	Project structured

💡 All folders and files created to organize FastAPI project logically.

Variable Tracker

Folder/File	Start	After Step 3	After Step 6	After Step 9	Final
project_root/	Not exist	Exists	Exists	Exists	Exists
app/	Not exist	Exists	Exists	Exists	Exists
app/api/	Not exist	Exists	Exists	Exists	Exists
app/models/	Not exist	Not exist	Exists	Exists	Exists
app/schemas/	Not exist	Not exist	Exists	Exists	Exists
app/core/	Not exist	Not exist	Exists	Exists	Exists
app/db/	Not exist	Not exist	Not exist	Exists	Exists
tests/	Not exist	Not exist	Not exist	Exists	Exists
main.py	Not exist	Not exist	Not exist	Exists	Exists

Key Moments - 3 Insights

Why do we separate 'models' and 'schemas' folders?

Models define how data is stored (database), schemas define how data is validated and sent over the network. See steps 4 and 5 in execution_table.

Why is 'tests' folder outside 'app' folder?

Tests are kept separate to avoid mixing test code with production code. This separation helps clarity and deployment. See step 8.

What is the role of 'main.py'?

'main.py' is the entry point that starts the FastAPI server. It imports routes and runs the app. See step 9.

Visual Quiz - 3 Questions

Look at the execution_table, at which step is the 'schemas' folder created?

A Step 3

B Step 5

C Step 7

D Step 9

💡 Hint

Check the 'Folder/File Created' column for 'app/schemas/' in execution_table rows.

According to variable_tracker, which folder appears last in the project structure?

A tests/

B app/db/

C app/api/

D app/core/

💡 Hint

Look at the final column in variable_tracker to see which folders exist at the end.

If we skip creating 'app/core/', what impact does it have on the project?

A No impact, core is optional

B Routes will not work

C Config and security code will have no dedicated place

D Database connection will fail

💡 Hint

Refer to step 6 in execution_table describing 'app/core/' purpose.

Concept Snapshot

FastAPI folder structure:
- app/: main code
- app/api/: routes
- app/models/: database models
- app/schemas/: data validation
- app/core/: config and security
- app/db/: database connection
- tests/: test files
- main.py: app entry point
Organize by responsibility for clarity and maintainability.

Full Transcript

This visual execution shows how to organize a FastAPI project by creating folders step-by-step. We start with the project root, then add the app folder. Inside app, we create api for routes, models for database models, schemas for data validation, core for configuration and security, and db for database connection. Separately, we create a tests folder for test code. Finally, main.py is created as the entry point to start the FastAPI server. This structure helps keep code organized and easy to maintain.