mongoose-to-erd

Turn your Mongoose schemas into entity-relationship diagrams, automatically.

Generated from a real schema

Everything below is produced at build time by the actual package — the same generateErd() call you would make yourself, rendered through D2. Nothing here is a mock-up.

Every field, constraint and method.

The schema behind it

Four models with unique constraints, references, arrays of subdocuments, embedded objects, and instance/static methods.

tsx

import mongoose from "mongoose";
const User = mongoose.model("User", new mongoose.Schema({  email:   { type: String, required: true, unique: true },  name:    { type: String, required: true },  roles:   [String],  profile: { bio: String, avatarUrl: String },}));
const Post = mongoose.model("Post", new mongoose.Schema({  title:     { type: String, required: true },  slug:      { type: String, required: true, unique: true },  published: { type: Boolean, required: true },  author:    { type: mongoose.Schema.Types.ObjectId, ref: "User", required: true },  tags:      [{ type: mongoose.Schema.Types.ObjectId, ref: "Tag" }],}));
// …plus Tag and Comment
await mongooseToErdMain(["User", "Post", "Tag", "Comment"], mongoose.model);

What was extracted

getAllModelDefinitions() returns this typed description, which you can post-process before rendering.

User: 6 fields, 1 instance method(s), 1 static method(s)
Post: 9 fields
Tag: 4 fields
Comment: 6 fields

Usage

tsx

import mongoose from "mongoose";import { mongooseToErdMain } from "mongoose-to-erd";
import "./models/user";import "./models/post";
const { files } = await mongooseToErdMain(  ["User", "Post"],  mongoose.model,  { outDir: "docs/diagrams", timestamp: false });

Without touching the filesystem

generateErd() hands back the SVG and D2 source so you can embed, diff or serve them — which is exactly how this page is built.

tsx

const erd = await generateErd(names, mongoose.model);
erd.full.svg;     // rendered SVG stringerd.full.d2;      // the generated D2 sourceerd.models;       // the extracted schema definitions

Catching schema drift in CI

The D2 output is deterministic, so a committed diagram can be checked for drift on every build.

tsx

const { full } = await generateErd(names, mongoose.model);
if (full.d2 !== readFileSync("docs/schema.d2", "utf8")) {  throw new Error("Schema changed — regenerate docs/schema.d2");}