django-arch-check 0.4.2

A CLI tool to detect architectural problems in Django projects.

django-arch-check

A command-line architectural health checker for Django projects.

It scans source code statically and flags structural issues before they become entrenched technical debt:

• Fat models
• God apps
• Circular imports
• Missing service layer boundaries
• Celery tasks without retry
• Direct SQL usage
• N+1 query risks

Analyzing: /home/user/myproject

── Fat Models ──────────────────────────────
  [CRITICAL]  core/models.py → UserProfile (34 methods)

  Found 1 fat model(s).

── God Apps ────────────────────────────────
  [WARNING]   core/ owns 41% of total project code (860 / 2,102 lines)

  Found 1 god app(s).

── Circular Imports ────────────────────────
  No circular imports found.

── Missing Service Layer ────────────────────
  [WARNING]   orders/views.py → create_order() makes direct ORM calls

  Found 1 missing service layer issue(s).

── Celery Tasks Without Retry ──────────────
  [CRITICAL]  payments/tasks.py → send_invoice_email() — high-stakes task, no retry configured

  Found 1 Celery task(s) without retry.

---

Why

Django projects often drift toward the same architectural problems:

• Models absorb business logic until they become hard to reason about
• One app quietly turns into the center of the codebase
• View functions talk directly to the ORM and blur boundaries
• Celery tasks lose work because retries were never configured
• Circular imports pile up as module boundaries erode

These issues are easy to normalize and hard to see in code review. django-arch-check makes them visible early, in local development and in CI.

---

Installation

pip install django-arch-check

Requirements:

• Python 3.11+
• No Django runtime setup required

The tool is static-only: it reads source files, parses ASTs, and never imports your project code.

---

Quick Start

# Analyze a project and print findings to the terminal
django-arch-check analyze /path/to/project

# Generate a self-contained HTML report
django-arch-check analyze --format html /path/to/project

# Tune thresholds
django-arch-check analyze \
  --fat-model-threshold 20 \
  --god-app-threshold 40 \
  /path/to/project

---

Ignore Detectors

Use --ignore to skip one or more detectors entirely.

django-arch-check analyze --ignore fat_models /path/to/project
django-arch-check analyze --ignore fat_models --ignore god_apps /path/to/project

Valid detector names:

• fat_models
• god_apps
• circular_imports
• missing_service_layer
• celery_tasks
• direct_sql
• n_plus_one

If an invalid detector name is passed, the CLI exits with a clear error:

Error: Unknown detector 'fat_modelz'. Valid detectors are: fat_models, god_apps, circular_imports, missing_service_layer, celery_tasks, direct_sql, n_plus_one

In HTML reports, skipped detectors are shown as:

⊘ Skipped (--ignore flag)

---

Ignore Paths

Use --ignore-path to skip files whose relative path contains a given substring.

django-arch-check analyze --ignore-path legacy/ /path/to/project
django-arch-check analyze --ignore-path legacy/ --ignore-path archive/ /path/to/project

This is applied across all detectors. If a file path contains the ignored string, that file is not analyzed.

Examples:

• --ignore-path legacy/ skips files under paths like legacy/models.py
• --ignore-path archive/ skips files under paths like apps/orders/archive/tasks.py

Path ignores are substring-based, not glob-based.

---

CLI Options

Current django-arch-check analyze --help output:

Usage: main analyze [OPTIONS] PROJECT_PATH

  Analyze a Django project at PROJECT_PATH for architectural issues.

Options:
  --fat-model-threshold N  Flag models with >= N non-dunder methods.  [default:
                           15]
  --god-app-threshold PCT  Flag apps owning >= PCT% of total project LOC.
                           [default: 30]
  --ignore DETECTOR        Ignore a detector by name. Repeatable.
  --ignore-path PATH       Skip files whose path contains PATH. Repeatable.
  --format [text|html]     Output format: text (stdout) or html (arch-
                           report.html).  [default: text]
  --help                   Show this message and exit.

Exit Codes

Code	Meaning
0	No critical findings
1	At least one critical finding, or a CLI usage error

This makes the tool suitable for CI gating.

---

Detectors

Fat Models

Flags Django model classes with too many non-dunder methods.

• Warning: method_count >= threshold
• Critical: method_count >= threshold * 2
• Default threshold: 15
• Default critical boundary: 30

Notes:

• Counts def and async def
• Ignores dunder methods like __str__
• Scans Python files across the project

God Apps

Flags Django apps that own too much of the total project LOC.

• Warning: percentage >= threshold
• Critical: percentage >= threshold + 20
• Default threshold: 30%
• Default critical boundary: 50%

Notes:

• LOC excludes blank lines and standalone comment lines
• Requires at least 2 Django apps before it reports findings
• Uses models.py or apps.py to identify app directories

Circular Imports

Flags cycles in the intra-project import graph.

• Critical: any detected cycle

Notes:

• Only top-level imports are analyzed
• Function-level imports are intentionally ignored
• Reports both short and multi-node cycles

Missing Service Layer

Flags views that contain too many direct ORM calls and likely need service-layer extraction.

• Warning: 2 or more direct Model.objects.* calls in a single view function or method
• Critical: 4 or more direct Model.objects.* calls in a single view function or method

Notes:

• Scans views.py files only
• Supports function-based views and class-based view methods
• Uses ORM call count, not raw line count

Celery Tasks Without Retry

Flags Celery tasks that lack retry configuration.

• Critical: task name contains payment, email, invoice, or notification, and has no retry config
• Warning: any other task with no retry config

Retry config is considered present when the decorator includes any of:

• max_retries
• autoretry_for
• retry_backoff

Notes:

• Detects both @shared_task and @app.task
• Skips migration files

Direct SQL

Flags raw SQL patterns that bypass Django's ORM.

Detected patterns:

• cursor.execute(
• connection.cursor()
• .raw(
• .extra(select=

Severity:

• Warning only

Notes:

• Migration files are excluded

N+1 Query Risks

Flags likely N+1 query patterns inside loops and list comprehensions.

• Warning: ORM call inside a loop or list comprehension, with no select_related or prefetch_related found in the same function scope

Notes:

• Scans views.py and serializers.py
• Looks for X.objects.method(...) patterns inside loops
• Heuristic by design; false positives and false negatives are possible

---

HTML Report

django-arch-check analyze --format html /path/to/project

The generated arch-report.html is self-contained and works offline.

It includes:

• A health score from 0 to 100
• Summary counts for critical and warning findings
• One section per detector
• Skipped detector notes when --ignore is used

Health Score

The score is rate-based, not a simple fixed deduction per finding.

Formula:

critical_rate = criticals / total_findings
warning_rate  = warnings  / total_findings
raw           = 100 - (critical_rate * 60) - (warning_rate * 40)
penalty       = min(30, criticals * 2 + warnings * 0.5)
score         = max(0, round(raw - penalty))

This avoids driving large mature projects straight to zero while still rewarding lower-severity, lower-density finding profiles.

---

CI Integration

GitHub Actions

- name: Check Django architecture
  run: |
    pip install django-arch-check
    django-arch-check analyze ./

If you want to ignore legacy areas while still gating the rest of the codebase:

- name: Check Django architecture
  run: |
    pip install django-arch-check
    django-arch-check analyze --ignore-path legacy/ ./

To generate an HTML report artifact:

- name: Django architecture report
  run: |
    pip install django-arch-check
    django-arch-check analyze --format html ./

- name: Upload report
  uses: actions/upload-artifact@v4
  with:
    name: arch-report
    path: arch-report.html

---

How It Works

django-arch-check analyzes source code statically.

It:

• Walks the project tree
• Skips common non-source directories like .venv, node_modules, and caches
• Parses Python files with the standard-library ast module
• Runs each detector independently through a central analyzer

It does not:

• Import your Django project
• Require configured settings
• Hit the database
• Execute application code

That makes it safe to run in CI, pre-commit hooks, and partially broken repos.

---

Limitations

• Circular import detection only covers top-level imports
• --ignore-path uses substring matching, not glob syntax
• Missing service layer detection only scans files literally named views.py
• N+1 detection is heuristic and only reasons within a single function scope
• God app analysis requires at least 2 detectable Django apps

---

Development

git clone https://github.com/RJ-Gamer/django-arch-check.git
cd django-arch-check

python -m venv .venv
source .venv/bin/activate   # Windows: .venv\Scripts\activate

pip install -e ".[dev]"

pytest -q --basetemp .pytest-tmp

django-arch-check analyze /path/to/project

Project Structure

django_arch_check/
├── __init__.py
├── cli.py
├── analyzer.py
├── report.py
└── detectors/
    ├── __init__.py
    ├── fat_models.py
    ├── god_apps.py
    ├── circular_imports.py
    ├── missing_service_layer.py
    ├── celery_tasks.py
    ├── direct_sql.py
    └── n_plus_one.py

tests/
├── conftest.py
├── test_analyzer.py
├── test_fat_models.py
├── test_god_apps.py
├── test_circular_imports.py
├── test_missing_service_layer.py
├── test_celery_tasks.py
├── test_direct_sql.py
├── test_n_plus_one.py
├── test_report.py
└── test_cli.py

Adding a New Detector

1. Create django_arch_check/detectors/my_detector.py
2. Add a detect(...) function that returns finding dataclasses
3. Add the detector to analyzer.py and AnalysisResult
4. Add text output in cli.py
5. Add HTML rendering support in report.py
6. Add tests

---

Contributing

Issues and pull requests are welcome.

If you are proposing a larger detector or behavior change, opening an issue first is appreciated.

---

Version

The next release version for this change set is 0.4.0.

---

License

MIT. See LICENSE.