Book Image

The Official Guide to Mermaid.js

By : Knut Sveidqvist, Ashish Jain
Book Image

The Official Guide to Mermaid.js

By: Knut Sveidqvist, Ashish Jain

Overview of this book

Mermaid is a JavaScript-based charting and diagramming tool that lets you represent diagrams using text and code, which simplifies the maintenance of complex diagrams. This is a great option for developers as they’re more familiar with code, rather than using special tools for generating diagrams. Besides, diagrams in code simplify maintenance and ensure that the code is supported by version control systems. In some cases, Mermaid makes refactoring support for name changes possible while also enabling team collaboration for review distribution and updates. Developers working with any system will be able to put their knowledge to work with this practical guide to using Mermaid for documentation. The book is also a great reference for looking up the syntax for specific diagrams when authoring diagrams. You’ll start by learning the importance of accurate and visual documentation. Next, the book introduces Mermaid and establishes how to use it to create effective documentation. By using different tools, editors, or a custom documentation platform, you’ll also understand how to use Mermaid syntax for various diagrams. Later chapters cover advanced configuration settings and theme options to manipulate your diagram as per your needs. By the end of this book, you’ll be well-versed with Mermaid diagrams and how they can be used in your workflows.
Table of Contents (19 chapters)
1
Section 1: Getting Started with Mermaid
7
Section 2: The Most Popular Diagrams
12
Section 3: Powerful Diagrams for the Advanced User

Attaching Relationships between Entities

Relationships in an ER diagram can be defined as logical connections between two entities. You saw an example of a relationship earlier in this chapter in the How is an entity represented? section, but here, you will learn all about the different types of relationships between entities that are supported by Mermaid. You will learn how to define them and what they look like when rendered.

In Mermaid, the syntax of adding a relationship between two entities can be achieved by placing a special line with symbols on it (relationship) between the two entity name identifiers. This relationship can have different arrowheads to represent different types of relationships. The syntax looks like this:

entityId relation entityId : labelText

Please note that you need all the parts of this syntax (or statement). In Mermaid, the relation part is broken down into three segments:

  1. Beginning Arrowhead: Represents the cardinality of the first entity...