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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.

Related MCP server: django-mcp-inspector

🆓 Paid-tier capabilities, free and MIT

Schema review is a paid category nearly everywhere. A bot that reviews every pull request, analysis that follows a queryset past the function it was built in, a check that catches schema drift, index advice grounded in real table statistics — those normally sit behind a per-seat or per-database subscription.

All of it is here, MIT-licensed, with no tier gate, no seat count, no account, and no telemetry:

There is no Pro tier, and none is planned. If the tool saves you an afternoon, a star is the entire ask.

📊 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

💥 Blast radius

The review-time question a schema change actually raises: what does this hit? Every destructive migration operation becomes a target carrying its risks, every place in the codebase that still reads it, and — for whole-model operations — the cascade fallout.

migration-risk, impact and cascade each answer a third of that; nobody joins them by hand, so the tool does. --format markdown is a postable PR comment; --stats turns "probably populated" into ~41 000 000 rows, 12.0 GB from a read-only query you run yourself, with no database credential anywhere near CI.

🧭 Schema drift

makemigrations --check without booting Django. Each app's migrations are replayed in order into the field set they imply, then compared against what models.py declares.

Django's own check needs a working settings module, an importable app registry and every dependency installed — unavailable on a cold clone or a broken venv, which is exactly when the answer is cheapest to act on. Only the dangerous direction fails the build: a field declared but never migrated means the column will not exist, and the first query touching it errors.

🎯 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:

erDiagram
  User {
    CharField display_name
  }
  Tag {
    CharField name
  }
  Post {
    CharField title
    DateTimeField created_at
  }
  Comment {
    TextField body
  }
  Post }o--|| User : "author [CASCADE, as posts]"
  Post }o--o{ Tag : "tags [as posts]"
  Comment }o--|| Post : "post [CASCADE, as comments]"
  Comment }o--|| User : "author [SET_NULL]"

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
django-orm-lens impact author                # what still references a field
django-orm-lens blast-radius -f markdown     # risks + who still reads them
django-orm-lens drift                        # migrations vs models, no boot
django-orm-lens stats-sql                    # read-only SQL for --stats

impact, blast-radius, drift and stats-sql ship in py-1.7.0 and later.

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. Four zero-config ways to block them:

Blast-radius PR bot — the whole schema review as one comment, updated in place on every push instead of a new comment each time:

name: Schema review
on: pull_request

permissions:
  contents: read
  pull-requests: write        # only for `comment: true`

jobs:
  blast-radius:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: FROWNINGdev/django-orm-lens@action-v1
        with:
          command: blast-radius
          only-changed: true          # scope to migrations this PR touches
          comment: true               # post once, then update in place
          github-token: ${{ github.token }}

The comment goes up before the job fails, so a blocked PR still explains why. only-changed reads the PR's file list from the API rather than git diff, because actions/checkout defaults to fetch-depth: 1 and the base commit is not in the local history. On push events both flags skip with a notice instead of failing, so one workflow covers both triggers.

The Action installs from PyPI, so blast-radius and drift need py-1.7.0 or later — pin it with version: 1.7.0 if your workflow must not drift. To run an unreleased build instead, add install: false and install the source yourself; this repo's own workflow does exactly that, and is what verifies the Action on every PR.

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

# .pre-commit-config.yaml
repos:
  - repo: https://github.com/FROWNINGdev/django-orm-lens
    rev: py-v1.8.1
    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 and blast-radius exit 1 on critical findings, drift exits 1 when a field is declared but never migrated. 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)

py-1.7 → 1.8 — the schema-intelligence wave

• blast-radius — migration risks joined with what still reads the schema they touch, as a PR bot (comment: true, sticky, only-changed)

• drift — makemigrations --check without booting Django

• impact <name> — what still references a model or field, grouped by Django layer

• blast-radius --stats + stats-sql — optional production row counts from read-only SQL you run yourself (the tool never holds a DB credential)

• nplusone resolves across functions — a queryset returned by a helper is followed into the loop that consumes it

• blast_radius, drift and impact exposed as MCP tools — thirteen tools for AI agents

• drift documents its !! / ~ marks in the report and in --help — reported by @sevdog (#57)

• drift follows inheritance from abstract bases — an abstract base's fields count as the concrete child's own, as Django treats them — reported by @sevdog (#58)

• suggest-index recognises the indexes Django already made — primary key (pk and id are one lookup), db_index, unique, foreign keys, unique_together, UniqueConstraint — reported by @sevdog (#60), same cause independently found by @RinZ27 (#61)

• A sixth golden fixture — Read the Docs joins Zulip, Saleor, Wagtail, django-CMS and Mezzanine, putting the parser under 75 models and 538 fields of real-world Django — contributed by @JJordan0C (#62, closing #51)

• django-taggit TaggableManager is read as the M2M it is — through taggit.TaggedItem to taggit.Tag, through= overrides honoured, in both the Python and the TypeScript parser — contributed by @Guflly (#63, closing #50)

• DOL021 states the USE_TZ default correctly — False through Django 4.2, True from 5.0, with the startproject template's USE_TZ = True since 4.0 called out as the separate thing it is — and no longer claims timezone.now() is always aware UTC — found by @Justine0211 while translating the page (#52)

• The parity_input.py fixture carries the models import a real models.py would have — contributed by @RinZ27 (#64)

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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