Entity-relationship diagram from OData $metadata

An OData $metadata document is a precise data model, but reading the XML of a 200-entity SAP service is slow going. The viewer draws it instead:

Entity types as boxes with key properties marked, property types and nullability.
Navigation properties as edges labelled with their multiplicities (1, 0..1, *) on both ends — for V2 taken from the association, for V4 from the property type and its partner.
Inheritance (BaseType) as a separate edge style, complex types as their own boxes.
Focus mode: select an entity and show only the types within one or two hops.
The layout is computed automatically (layered, left to right) and leaves room for edge labels.

The diagram is one of five synchronised views. Clicking a box opens the entity type in the detail panel; the source view jumps to its line in $metadata; the data explorer queries its entity set.

Exports

Format	Use
PNG	slides, tickets, chat
SVG	documentation that should stay sharp
Mermaid `erDiagram`	Markdown docs, GitHub/GitLab READMEs, Confluence
Markdown	a full text description of every type and property

Works with every OData version

EDMX 1.0 (V2/V3) with associations, EDMX 4.0 (V4/V4.01) with partners and referential constraints, and CSDL JSON are read into one model, so a V2 and a V4 version of the same service produce the same diagram. Try Northwind V2 and Northwind V4.

See the TripPin diagram

Questions

Can I put the diagram into my documentation?

Yes. Export PNG or SVG from the diagram toolbar, or the Mermaid erDiagram text from the export menu — GitHub, GitLab, Confluence and many wikis render Mermaid directly.

My service has hundreds of entity types. Does that work?

Up to 150 types are drawn at once. Pick an entity type and use focus mode to draw only its neighbourhood, which is usually what you want for a large SAP service anyway.