entmaid

A CLI for generating entity-relationship diagrams in mermaid.js for the Go entity framework ent.

Install

To otherwise install it:

go install github.com/troypoulter/entmaid@latest

Features

The generated diagram aims to be as SQL like as possible, so it will define:

• Primary (PK) and Foreign (FK) Keys: This helps to see how the different relationships are made, especially for foreign keys where if using the standard edges in ent will specify in the schema the actual field name.
• Display Actual Many-to-Many (M2M) Table: How ent shows M2M through the default edges approach doesn't make clear that it creates a separate table, so we show you what it actually looks like!

Additional useful features outside of the generated diagram itself:

• Automatically insert your diagram code into your README: You can support living design documents by having entmaid to place the generated diagram inside an existing README or any markdown file, so it always stays up-to-date!

Here's an example diagram generated, checkout the Usage section on how it was generated!.

erDiagram
 Car {
  int id PK
  string model
  time-Time registered_at
  int user_cars FK
 }

 Group {
  int id PK
  string name
 }

 group_users {
  int group_id PK,FK
  int user_id PK,FK
 }

 User {
  int id PK
  int age
  string name
 }

 Group |o--o{ group_users : users-groups
 User |o--o{ Car : cars-owner
 User |o--o{ group_users : groups-users

Usage

Note

There are numerous examples you can inspect through the examples folder and also by inspecting the Makefile.

A CLI for generating a mermaid.js Entity Relationship (ER) diagram for an Ent Schema, without needing a live database!

Usage:
  entmaid [flags]

Flags:
      --endPattern string       target directory for schemas (default "<!-- #end:entmaid -->")
  -h, --help                    help for entmaid
  -o, --outputType outputType   set the desired output type: can be 'markdown' (useful for GitHub), 'plain' (default markdown)
  -s, --schema string           directory containing the schemas (default "./ent/schema")
      --startPattern string     target directory for schemas (default "<!-- #start:entmaid -->")
  -t, --target string           target file to output diagram (default "./ent/erd.md")

1. Start by putting the desired startPattern and endPattern values into your target file so entmaid knows where to insert the diagram.

2. Run the command passing through all the relevant parameters, this example will be using the command from the Makefie, example.readme:

   entmaid -s ./examples/start/schema -t ./README.md -o markdown --startPattern "<!-- #start:entmaidReadme -->" --endPattern "<!-- #end:entmaidReadme -->"

3. You should now see the generated diagram in the target file, you can check out the diagram below as the above command generated it!

Inspiration & Acknowledgements

I was inspired by both a8m/enter and hedwigz/entviz for generating mermaid diagrams from reading in just the ent schema folder.

I created this as I wanted to support additional features (as listed in the Features section!), especially being able to insert the generated diagram code directly into my markdown files has been awesome!

This is also my first publihsed Go module and I wanted to give it a shot!