Django ORM Lens

What is Django ORM Lens about?

Django ORM Lens delivers schema‑intelligence for any Django codebase. By walking the source tree and parsing models.py (including split models/ packages), it builds a complete model graph that can be viewed in the VS Code sidebar, rendered as a live Mermaid ER diagram, queried via a command‑line interface, or accessed through MCP tools for AI agents.

How to use Django ORM Lens?

• VS Code / Cursor: install the extension from the Marketplace or Open VSX. The sidebar appears automatically, showing apps → models → fields with hover cards and quick‑fixes.
• Terminal / CI: pip install django-orm-lens (or uvx django-orm-lens scan). Run sub‑commands such as django-orm-lens er, django-orm-lens diff, django-orm-lens nplusone, or django-orm-lens migration-risk.
• AI agents: install with the extra mcp tag (pip install "django-orm-lens[mcp]"). Start the server via django-orm-lens-mcp or django-orm-lens mcp. Configure DJANGO_ORM_LENS_ROOT (or workspace_root argument) to point at the Django project.
• Docker: docker run --rm -v "$PWD:/workspace" ghcr.io/frowningdev/django-orm-lens scan --path .

Key features of Django ORM Lens

• Sidebar tree showing every app, model, field, and Meta option, sortable and searchable.
• Live ER diagram (Mermaid) that updates on file changes; exportable to SVG.
• Hover cards & jump‑to definition for foreign keys and relationships.
• Inline QuickFixes (16 static‑analysis rules) with Ruff‑style severity control.
• Factory generator that scaffolds factory_boy factories with Faker providers.
• Time‑travel schema diff between commits, with rename detection.
• Impact analysis to locate code that would break if a field/model is removed.
• Interactive query builder that inserts ready‑to‑run ORM snippets.
• MCP server exposing ten read‑only tools (list apps, describe model, cascade preview, ER diagram formats, migration DAG, index suggestions, signal graph, N+1 scan, etc.).
• CI integration via pre‑commit hooks, GitHub Action, or SARIF uploads.
• Zero‑dependency CLI (Python 3.9+), no DB, no runserver, works on broken venvs.

Use cases of Django ORM Lens

• Quickly answer "Which app defines Model X and how is it related?" when onboarding a new Django codebase.
• Enforce schema‑quality rules in CI pipelines to block risky migrations or N+1 patterns.
• Provide AI coding assistants (Cursor, Aider, Continue, Zed) with accurate, read‑only schema information without exposing the database.
• Generate visual documentation (ER diagrams) for stakeholder reviews or architectural diagrams.
• Scaffold test data factories and reduce boilerplate when writing unit tests.
• Perform impact analysis before refactoring models or removing fields.

FAQ from the Django ORM Lens

Does the tool send my code anywhere? No. All parsing and rendering happen locally; no telemetry or external calls are made.

Can it work without a virtual environment or a database? Yes. The parser reads source files directly and never imports Django, so it works on any checkout, even with missing dependencies.

Will it handle models split across multiple files? Yes, support for models/ packages has been available since v0.2.0.

What Python versions are supported? Python 3.9 and newer; Django 4.0‑5.2 are fully supported.

How do I configure the MCP server for an AI agent? Install the extra mcp package, run django-orm-lens-mcp, and set DJANGO_ORM_LENS_ROOT (or pass workspace_root in the call). The server then listens for MCP requests.

How can I export the ER diagram in other formats? Use django-orm-lens er -f dbml, -f d2, -f plantuml, or -f dot to generate DBML, D2, PlantUML, or Graphviz DOT files.

Can the extension be used in other Code‑derived editors? Yes. The VSIX works in VS Code, VSCodium, Code‑Server, Gitpod, and any Open VSX‑compatible fork.

What are the quick‑fix rules called? They use codes DOL001 … DOL032. Rules can be disabled inline (# django-orm-lens-disable-next-line DOL007) or globally via VS Code settings.

How does the schema diff handle renames? It uses Levenshtein distance plus field‑shape Jaccard similarity to treat a rename as a distinct event rather than an add‑and‑drop.

Is there a JetBrains/PyCharm plugin? Not currently; the tool focuses on VS Code and terminal/AI workflows.

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Django ORM Lens

The schema intelligence layer for Django.

Your entire model graph — live in your editor sidebar, gating your CI, and answering your AI agent over MCP. All from static parsing: no database, no runserver, no working venv.

Replaces: graph_models + django-schema-graph + hand-drawn ER diagrams + grep archaeology.

⚡ 10 seconds to first insight

uvx django-orm-lens scan      # or: pipx run django-orm-lens scan

Cold clone, broken venv, no settings module — you still get every app, model, field, and relation of the project in your terminal.

Then pick your surface — three distributions, one parser core:

MCP setup is one JSON block — see Integrations. Point DJANGO_ORM_LENS_ROOT at your Django project's absolute path.

📊 Traction

If the tool saves you a grep next time you touch a strange Django project — a star helps others find it.

📈 Star growth

⚡ Install

VS Code / Cursor / Windsurf (VS Code Marketplace):

code --install-extension frowningdev.django-orm-lens

VSCodium / code-server / Gitpod / any OSS Code fork (Open VSX):

codium --install-extension frowningdev.django-orm-lens

Or search Django ORM Lens in the Extensions view — same publisher frowningdev on both registries.

Terminal & AI coding agents:

pip install django-orm-lens              # CLI only
pip install "django-orm-lens[mcp]"       # + MCP server for AI agents

Requires Python 3.9+. Zero runtime dependencies for the CLI.

Docker (v0.6+):

docker run --rm -v "$PWD:/workspace" ghcr.io/frowningdev/django-orm-lens scan --path .

Multi-arch (amd64 + arm64). No Python required on the host. Good for CI and one-off audits.

🎯 The problem

Works offline. Works on a broken venv. Works on someone else's laptop. Works in CI.

You open a Django project. It has 20 apps. You need to answer a simple question:

"Which app owns the Order model, and how is it connected to User?"

Today, that means: Ctrl+P, "models", scroll through 30 hits, open five files, Ctrl+F for class Order, read through 400 lines of ForeignKey('otherapp.Something') strings, try to remember what you learned two files ago.

Half a day gone. Every time. On every project.

✨ With Django ORM Lens

📚 A tree of everything

Every app → every model → every field → every Meta option. Grouped by application, sorted alphabetically, expandable.

Icons distinguish CharField from ForeignKey from ManyToManyField at a glance.

🕸️ A live ER diagram

One command opens a Mermaid entity-relationship diagram of your entire schema. Watch it redraw as you edit. Export to SVG.

ForeignKey, OneToOneField, and ManyToManyField become proper cardinality arrows.

🔎 Hover for relations

Hover over ForeignKey('app.Model') in any Python file → a card pops up with the target model's fields, relations, and a "Jump to" link. No Ctrl+F, no file dialog.

🧭 Jump-to-definition

Click any field in the tree → cursor lands on the exact line. Filter the tree by app or model name. Split models/ packages are fully supported.

⚡ Zero configuration

No DJANGO_SETTINGS_MODULE. No runserver. Parses models.py statically. Works with a broken venv, a missing dependency, or on someone else's laptop.

🎨 Native VS Code UI

Dark theme. Light theme. Your theme. Follows your icon theme, your font, your key bindings. Nothing garish, nothing branded.

🚀 Power features

🎯 Inline QuickFixes (16 rules)

Static analysis over .py files with Ruff-style codes (DOL001..DOL032), Clippy-style Applicability, and per-rule severity overrides. .count() > 0 → .exists(), null=True on CharField, missing on_delete, datetime.now() → timezone.now() and a dozen more.

Suppress inline with # django-orm-lens-disable-next-line DOL007.

🧪 Factory generator

Right-click any model → factory_boy DjangoModelFactory scaffold with Faker providers keyed by field type. CharField(max_length) scales word-count buckets, DecimalField(N,D) computes left_digits=N-D, choices= maps to Iterator, M2M gets @post_generation. FK chains pull related factories transitively.

Also available as CodeLens above each model class.

🕰 Time-Travel Schema Diff

Pick a models.py, pick two commits, get a typed diff as PR-ready markdown. AddModel / DropModel / RenameModel / ModifyModel events with confidence-scored rename detection (Levenshtein + field-shape Jaccard).

Renames are first-class events, never Add + Drop. Blob-SHA LRU cache — commits that don't touch models.py share their parsed snapshot.

🔎 Impact analysis

"What breaks if I remove this field?" — right-click a field or model → workspace-wide scan grouped by Django layer (models, serializers, forms, admin, views, urls, templates, tests, migrations).

Findings carry a Certain / Likely / Possibly confidence tag. Handles ORM string refs (order_by("-author")), kwarg lookups (filter(author__id=1)), Meta.fields tuples, and template variables.

⚡ Interactive query builder

Right-click a field or model → pick a template → snippet inserted at cursor (with tab-stops) or in a fresh untitled buffer.

.filter(field=?) on an FK auto-appends .select_related(...), .annotate(post_count=Count('post_set')) honours related_name, .prefetch_related for M2M, .values('field').distinct(), .only('field').

🎨 Sidebar UX overhaul

Stable TreeItem.id — refresh no longer collapses the tree. Rich MarkdownString tooltips with command: deep-links. Activity-bar badge counts DOL### issues.

FileDecorationProvider badges: red ! on FK-without-on_delete, yellow ~ on null=True string fields (bubbles up to the parent Model row, Git-style).

📸 What it looks like

Live sample — real django-orm-lens er output, rendered by GitHub right here:

Also included in the extension:

• 🕸️ Live ER diagram — Mermaid cardinality arrows, edge labels (CASCADE, through Model, as related_name), theme-aware, one-click SVG export
• 🔎 Hover cards — over any ForeignKey('app.Model') or ManyToManyField(...), with a one-click jump link
• 🧭 CodeLens — above every class Model line: field count, relation count, and an Open ER diagram action
• 🎨 Named themes — auto / default / dark / forest / neutral for the diagram webview

🤖 For terminals and AI coding agents

The same parser that powers the VS Code extension ships as a standalone Python package — with an optional MCP (Model Context Protocol) server so any MCP-compatible AI agent can navigate your Django schema without importing Django or booting your app.

CLI

django-orm-lens scan -f json                 # every app, every model, every field
django-orm-lens describe blog.Post           # one model in Markdown
django-orm-lens list | fzf                   # flat app.Model — pipes anywhere
django-orm-lens er > schema.mmd              # ER diagram — Mermaid (default)
django-orm-lens er -f dbml > schema.dbml     # …or DBML: paste into dbdiagram.io
django-orm-lens er -f d2 > schema.d2         # …or D2 / plantuml / dot
django-orm-lens diff before.json after.json  # what a PR changes structurally
django-orm-lens nplusone --format github     # N+1 findings as PR annotations
django-orm-lens migration-risk -f sarif      # SARIF for GitHub Code Scanning
django-orm-lens suggest-indexes blog.Post    # Meta.indexes proposals from usage
django-orm-lens signals                      # sender→signal→handler graph
django-orm-lens migration-deps blog -f mermaid   # per-app migration DAG
django-orm-lens cascade blog.Author          # what one delete() takes down

Every command accepts --path <dir> and --exclude <glob>. nplusone / migration-risk / diff exit code 1 on findings — drop them into CI to block PRs on regressions.

MCP server

Register it once with your agent and it exposes ten read-only tools:

# Start it directly
django-orm-lens-mcp

# Or via the CLI subcommand
django-orm-lens mcp

Workspace resolution (py-1.3.0+). Every tool accepts an optional workspace_root argument on the call. Resolution priority: explicit arg → $DJANGO_ORM_LENS_ROOT → current working directory. Invalid or non-Django paths return a structured envelope ({"error": "WORKSPACE_NOT_DJANGO", "hint": "…"}) instead of empty results, so the agent can self-correct. Optional sandbox via DJANGO_ORM_LENS_ALLOWED_ROOTS (;-separated on Windows, : elsewhere).

🛡️ Gate your CI

Schema regressions are cheapest to catch the moment they enter a PR. Three zero-config ways to block them:

pre-commit — two hooks, nothing to install locally:

# .pre-commit-config.yaml
repos:
  - repo: https://github.com/FROWNINGdev/django-orm-lens
    rev: py-v1.6.0
    hooks:
      - id: django-orm-lens-nplusone
      - id: django-orm-lens-migration-risk

GitHub Action — findings appear as PR annotations with zero extra permissions:

- uses: FROWNINGdev/django-orm-lens@action-v1
  with:
    command: migration-risk      # or: nplusone
    format: github               # ::error / ::warning annotations on the diff

SARIF → Code Scanning — findings land in the repo Security tab:

- run: |
    pip install django-orm-lens
    django-orm-lens migration-risk --format sarif --exit-zero > lens.sarif
- uses: github/codeql-action/upload-sarif@v3
  with:
    sarif_file: lens.sarif

Exit codes are CI-native: diff and nplusone exit 1 on findings, migration-risk exits 1 on critical findings. Add --exit-zero for report-only mode.

🔌 Integrations

Example: Cursor / any MCP client

{
  "mcpServers": {
    "django-orm-lens": {
      "command": "django-orm-lens-mcp",
      "env": { "DJANGO_ORM_LENS_ROOT": "/abs/path/to/your/project" }
    }
  }
}

⚡ Performance

The regression suite parses the vendored model graphs of Zulip, Saleor, Wagtail, django CMS, and Mezzanine — 59 models across 13,478 lines of real-world models.py — in about 20 ms end-to-end on a laptop (21 ms best-of-3 on the repo's golden-fixture corpus; a <2 s guard runs in CI on every matrix cell).

Reproduce it yourself:

git clone https://github.com/FROWNINGdev/django-orm-lens && cd django-orm-lens/cli
pip install -e . && python -m pytest tests/test_golden_fixtures.py tests/test_golden_snapshots.py -q

🎯 Who this is for

• Django developers joining a codebase with 10+ apps and getting lost in models.py sprawl.
• Contract / freelance engineers who need to grasp an unfamiliar Django project in the first hour, not the first week.
• Teams onboarding new hires who want a one-glance schema view without spinning up documentation infrastructure.
• AI-agent power users (Cursor / Aider / Zed / Continue / any MCP-compatible client) who need the agent to answer schema questions accurately — without giving it database credentials or booting Django.
• CI pipelines that verify schema shape (e.g. "did we accidentally break a related_name?") without importing the project.
• Solo indie devs on a broken venv or someone else's laptop — no runserver, no manage.py migrate, still works.

🗺️ Market position

Django ORM Lens sits at the intersection of editor tooling and AI-agent tooling — a slot no existing package covers:

Django ORM Lens is the only tool that ships three surfaces from one parser: a VS Code extension (any Code fork), a zero-dep CLI (terminals + CI), and an MCP server (AI agents). All static. All free. All MIT.

🤔 How is this different?

django-schema-graph has not been updated since 2023-05 and does not test Django 5.x.

When you want something else

Honest boundaries: profiling a live request → django-debug-toolbar. Historical request profiling → django-silk. Query-count assertions inside a test suite → django-perf-rec. Production APM on real traffic → Scout / Sentry. Django ORM Lens deliberately stays static — it's the layer that works before the app can even boot, and the only one your CI and your AI agent can use on any checkout.

⚙️ Configuration

The defaults are opinionated and sensible. If you need to tweak:

// .vscode/settings.json
{
  "djangoOrmLens.excludeGlobs": [
    "**/migrations/**",
    "**/node_modules/**",
    "**/venv/**",
    "**/.venv/**",
    "**/env/**"
  ],
  "djangoOrmLens.autoRefresh": true
}

🔬 Rule catalogue

Sixteen editor-side checks (DOL001–DOL032) with Ruff-style codes, per-rule severity, and Clippy-style applicability — plus fifteen CLI-side migration-risk rules and the static N+1 analyzer. Every rule now has its own documentation page.

→ Full rule reference — every code with bad/good examples, QuickFix behaviour, and suppression syntax.

Suppress inline

# django-orm-lens-disable-next-line DOL007
for user in User.objects.all():
    print(user.profile)  # not flagged

qs.count() > 0  # django-orm-lens-disable-line DOL001

# django-orm-lens-disable DOL011  ← on its own line, kills DOL011 for the rest of the file

Applicability follows Rust's Clippy: safe fixes can be applied automatically ("Fix All"), suggestion fixes are offered as a QuickFix but reviewed, unsafe findings never auto-apply. Fixes are separated from analyzers (Roslyn-style), so one rule can grow multiple fixers over time without touching detection logic.

🧭 Commands

Open the command palette (Ctrl+Shift+P / Cmd+Shift+P) and type "Django ORM Lens":

🗺️ Roadmap

Shipped

• Sidebar tree grouped by app
• Live Mermaid ER diagram
• Hover cards over ForeignKey('app.Model')
• Filter tree by name
• Split models/ package support
• Export ER diagram as SVG
• Python CLI + MCP server for terminals and AI agents
• Welcome view for empty workspaces
• Path-safe jump-to-definition and sanitized hover markdown
• v0.3.0 — CodeLens above each model class (N fields · N relations · Open ER diagram)
• v0.3.0 — Edge labels on the diagram (CASCADE, SET_NULL, PROTECT, related_name)
• v0.3.0 — Named color themes (auto / default / dark / forest / neutral)
• v0.3.1 — through_model on M2M edges (contributed by @kingrubic)
• v0.3.1 — Listed in the official MCP Registry + Glama.ai
• v0.6.0 — CLI nplusone — static N+1 detector (FK/M2M access inside loops without select_related/prefetch_related)
• v0.6.0 — CLI migration-risk — flags risky operations in migrations/*.py (15 rules today)
• v0.6.0 — CLI diff — compare two schema JSON dumps for PR review
• v0.6.0 — ER-diagram minimap color-codes nodes by Django app
• v0.6.0 — README translations: 🇷🇺 Russian, 🇪🇸 Spanish, 🇨🇳 Chinese
• v0.6.0 — Docker image on GHCR: docker run ghcr.io/frowningdev/django-orm-lens
• v0.7.0 — settings.AUTH_USER_MODEL resolves everywhere: n+1 reverse-relations, signal senders, Mermaid ER, VS Code webview, inbound-relation panel, React ER
• v0.7.0 — AST-based field parser: ForeignKey(on_delete=CASCADE, to='User') resolves regardless of kwarg order (Python + TS parity)
• v0.7.0 — Public shared helpers: find_user_model, resolve_related_tail, find_model, iter_workspace_py_files (Python) + findUserModel, resolveRelatedTail (TS)
• v0.7.0 — --verbose no longer walks the tree twice; WorkspaceIndex.scanned_files carries the count
• v0.7.3 — PEP-526 type annotations on fields (jti: CharField[str] = models.CharField(...)) now parse — reported by @jsabater (#25) with a clean Django Ninja 1.6 repro
• v0.7.4 — PEP-695 generic class headers (Python 3.12+): class Container[T](models.Model): now parses
• v0.7.5 — Aliased models module (from django.db import models as m) and third-party field packages (jsonfield.JSONField) now detected
• v0.7.6 — Tab-indented model bodies now parse (editors defaulting to tabs no longer show empty models)
• v0.8.0 — Inline QuickFixes: 16 rules (DOL001..DOL032) with per-rule severity + Ruff-style select/ignore + inline # django-orm-lens-disable-next-line
• v0.8.0 — Factory generator: factory_boy scaffold from any model with Faker providers keyed by field type
• v0.8.0 — Time-Travel Schema Diff: pick two commits → typed markdown diff with first-class rename detection
• v0.8.0 — Impact analysis: workspace-wide field-reference scan across every Django layer with Certain/Likely/Possibly confidence tags
• v0.8.0 — Interactive Query Builder: right-click → template → snippet inserted at cursor, grammar-aware (FK gets .select_related, related_name honoured)
• v0.8.0 — Sidebar UX overhaul: stable TreeItem.id, MarkdownString tooltips with command: deep-links, FileDecorationProvider badges, TreeView.badge on the activity bar, three when-gated viewsWelcome states

v1.5.0 — the "one core, three surfaces" wave

• CI formats: SARIF 2.1.0 + --format github PR annotations for nplusone and migration-risk
• Four analyzers promoted from MCP-only to the CLI: suggest-indexes, signals, migration-deps, cascade
• er --format dbml | d2 | plantuml | dot — community-standard diagram exports (dbdiagram.io, D2, PlantUML, Graphviz — dot contributed by @JJordan0C)
• Three new migration-risk rules: runpython_no_reverse, alter_unique_together_lock, alter_index_together_deprecated — 15 total
• pre-commit hooks (django-orm-lens-nplusone, django-orm-lens-migration-risk) + composite GitHub Action
• docs/rules/ — a documentation page for every rule (19 pages)
• Golden-snapshot regression suite over 59 real-world models (Zulip / Saleor / Wagtail / django CMS / Mezzanine); ruff + mypy now gate CI
• Migration dependency graph — migration-deps (text / json / mermaid)

Next

• ORM query autocomplete inside .filter() / .exclude() / .annotate() (#3)
• App / model toggle checkboxes to declutter huge schemas
• DOL rule engine ported into the Python CLI — one rule catalogue, three surfaces

Later

• Third-party field support (django-mptt, django-taggit, django-model-utils)
• JetBrains / PyCharm plugin (if there is demand)

Vote by 👍-ing the corresponding issue.

❓ FAQ

🆘 Support

• 🐛 Bug reports — GitHub Issues (please include a minimal models.py snippet)
• 💡 Feature requests / ideas — GitHub Discussions
• 📝 Marketplace reviews — rate the extension (the fastest signal that keeps this project moving)
• 🐍 PyPI page — pypi.org/project/django-orm-lens
• 💚 Sponsor — github.com/sponsors/FROWNINGdev

📜 License

MIT © FROWNINGdev

Made for developers who care about their codebase.

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