Graph Basics

We will generate the basic elements of a labeled property graph:

1. Round circles for vertices
2. Labeled edges

We will use the following conventions:

1. Vertices use UpperCamelCase
2. Edge labels use UPPER_CASE_WITH_UNDERSCORES

Our graphs will use a Left-to-Right orientation. Other layout options you can use are:

• LR - for Left-to-Right orientation
• TD or TB - for Top-Down Top to Bottom orientation
• BT - bottom to top
• RL - right to left

Each of our drawings begin with the keyword graph and the automatic layout algorithm. So for graphs with Left-to-Right layouts we start our drawing with:

graph LR

Vertex Circles

There are many shapes you can make a node in a graph. For our high-level graph data models we will stick to circles which we indicate by surrounding a Vertex Label with double parenthesis ((`` and))```.

graph LR
     id1((Provider))
     id2((Patient)

Labeled Directed Edges

Now let's add a directed edge with a label on it between the two vertices. We will do this by adding one addition line between the two vertex statements. The line must start with a double dash and end with a dash-dash-greater-than character like this:

Here is the labeled directed edge line:

-- HAS_PATIENT -->

The Mermaid documentation calls this text-on-link

graph LR
    id1((Provider))
    -- HAS_PATIENT -->
    id2((Patient))

You can also remove the greater than > in the link to make the link an undirected edge. There are other link options you can use such as a dotted link.