From an empty file to generated DDL

Install the extension

From the Extensions view in VS Code, search for LPG Modeler. Or from the command line:

code --install-extension pavlyshyn.lpg-modeler

To build it yourself instead, clone the repository and package it:

git clone https://github.com/Volland/lpg-modeler
cd lpg-modeler
npm install
npm run build
npx @vscode/vsce package --no-dependencies # run inside packages/vscode

Then install the resulting .vsix with Extensions: Install from VSIX… in the command palette.

Create a model file

The file name matters: the extension activates on *.lpg.yaml and *.lpg.yml. Create catalog.lpg.yaml with a namespace and one node type.

namespace:
  prefix: catalog
  iri: https://example.org/vocab/catalog#

nodes:
  Product:
    key: [sku]
    props:
      sku: { type: string, required: true }
      title: { type: string, required: true }
      price: { type: float }

Completion and hover work immediately — the model format ships as a JSON Schema the extension contributes to the YAML tooling, so you get structural errors as you type.

Open the canvas

Run LPG: Open Canvas from the command palette. The diagram opens beside the file, with an ERD box per node type and one row per property.

From there you can add a node type, add a property, rename in place, draw an edge by dragging from one box to another, set an abstract parent, and choose which key a type uses. Each of those becomes a targeted edit to the YAML — you will see the file change under the diagram.

Typing in the YAML works the same way in reverse: the canvas redraws from the file on every keystroke. If the file stops being valid YAML mid-edit, the last good diagram stays on screen with a notice rather than blanking.

Generate a schema

Run LPG: Generate Schema and pick a target. The artifact is written next to the model and opened beside it:

catalog.lpg.yaml       # yours
catalog.ladybug.cypher # generated
catalog.neo4j.cypher   # generated
catalog.shacl.ttl      # generated
catalog.owl.ttl        # generated

If the target cannot enforce something the model asks for, you get a warning telling you how many downgrades occurred, a diagnostic per downgrade in the Problems panel, and a comment at the exact line of the artifact where the loss happens.

A model with errors never produces an artifact at all.

Split the diagram into views

One diagram of a whole model stops being readable somewhere past a few dozen types. Create a view from the canvas, or write the sidecar by hand as catalog.views.yaml:

views:
  overview:
    include: ["*"]
  pricing:
    include: ["Product", "PriceBand"]
    expand: 1   # also pull in immediate neighbours

Validation reports any type that has fallen out of every view, so diagrams do not quietly stop covering the model as it grows.

Check it in CI

The command line tool runs the same resolution and validation as the editor, with no editor present:

npx @lpg/cli check catalog.lpg.yaml
npx @lpg/cli emit  catalog.lpg.yaml --target ladybug --out ./schema

check exits non-zero when the model has errors, so a pull request can be gated on schema validity. See the CLI reference for every flag.