t2erd

Text 2 ER Diagram

Features:

• Draw tables
• Draw relationships
• Draw self-referential relationships
• Support colours
• Support custom positions
• Support custom table dimensions

Usage

CLI

As a CLI tool, it automatically converts the ERD into an SVG (use t2erd-svg to convert to png instead). In addition it will print the SVG code to the terminal.

From source

git clone https://github.com/dosaki/t2erd
node ./t2erd/src/t2erd.js -i=/path/to/input.erd

Form NPM

or if installed globally via

npm install -g t2erd
t2erd -i=/path/to/input.erd

Library

Using as a library:

const t2erd = require('./t2erd.js');
const diagramText = `
[some_table]
some_column
`
const svgString = t2erd(diagramText);

Syntax

Borrowed some of the syntax from https://github.com/BurntSushi/erd

Comments

Comments start with // and are ignored by the parser.

// Comment

Anything to the right of a // is also a comment

Foo // Comment

Tables

Table definitions start with a name between square brackets ([Table Name]) and end when the file ends or when another table definition starts.

Column names are any line written under the beginning of a table definition and can be denoted with * to mark them as a Primary Key or + for a Foreign Key.

[Table1Name]
*primary key
column
+foreign key

You can optionally specify an alias for the table name (to make it easier for layout definition) by adding any text after a - (any whitespace is ignored).

[Table1Name] - t1
*primary key
column
+foreign key

Table Styles

Styles can be declared anywhere after a table has been defined and will always belong to the previously defined table. They always start with a { and end with a }. Properties must be a key/value pair separated by a :. Each key/value pair can be separated by a ; when inline.

The supported styles, so far are:

background: #96c7ff;   // Table background colour
stroke: #385372;       // Table border colour
color: #2c4056;        // Table text colour

They can be declared inline:

[Table]
{background:red;stroke:green;}
column1
column2

And non inline:

[Table]
{
  background:red;
  stroke:green;
}
column1
column2

A table can have multiple styles definitions as well... if that's your thing. The latest ones will always overwrite the previous if they contain properties that had been defined already.

[Table]
{
  background:red;
  stroke:green;
}
column1
{background:blue;} # On second thought, I want blue and I don't feel like updating the definition above.
column2

Table Relationships

Table relationships are declared with a table name followed by the cardinality a double dash, the other table cardinality and the table it links to.

table1 *--1 table2

Supported cardinality characters are:

• * for many
• 1 for one

These can be declared anywhere even in the middle of table column definitions.

Layouts

You can specify how you want the tables to be organized by declaring a layout. If your diagram is too complex I'd recommend using this since the automatic position calculations might not organize things the tables in the best way.

Any line starting with a | is added to a layout in order of appearance:

|p| |
|u|i|

Where | is the divider between the tables and between a set of | is a table name or alias.

Each line of a layout can be separated by any other definition and it'll still belong to the layout

Example

// Users table that only contains login info
[user] - u
{
  background: #96c7ff;
  stroke: #385372;
  color: #2c4056;
}
*id
username
hashed_password

// This one contains other information about the user
[user_info] - i
{background:#ceffd0;stroke:#4d664e;}
*id
+user_id
email
bio
date_of_birth
registered_date

user_info 1--1 user

// Posts (a thread starts on a post without a parent)
[post] - p
*id
+poster
+parent
content
timestamp

post *--1 post
post *--1 user

|p| |
|u|i|