Better example and review changes

diagrams/__init__.py

@@ -165,7 +165,7 @@ class Diagram:
 
     def connect(self, node: "Node", node2: "Node", edge: "Edge") -> None:
         """Connect the two Nodes."""
-        self.dot.edge(node.hashid, node2.hashid, **edge.to_dot())
+        self.dot.edge(node.hashid, node2.hashid, **edge.attrs())
 
     def subgraph(self, dot: Digraph) -> None:
         """Create a subgraph for clustering"""
@@ -403,7 +403,7 @@ class Edge:
                  reverse: bool = False,
                  label: str = "",
                  color: str = "",
-                 style: str = ""
+                 style: str = "",
                  ):
         """Edge represents an edge between two nodes.
 
@@ -420,9 +420,9 @@ class Edge:
         self.node = node
         self.forward = forward
         self.reverse = reverse
-        self.label = label
-        self.color = color
-        self.style = style
+
+        # graphviz complains about using label for edges, so replacing it with xlabel
+        self._attrs = {"xlabel": label, "color": color, "style": style}
 
     def __sub__(self, other: Union["Node", "Edge", List["Node"]]):
         """Implement Self - Node or Edge and Self - [Nodes]"""
@@ -454,15 +454,12 @@ class Edge:
         result = []
         for o in other:
             if isinstance(o, Edge):
-                o.color = self.color
-                o.label = self.label
-                o.style = self.style
                 o.forward = forward if forward is not None else o.forward
                 o.reverse = forward if forward is not None else o.reverse
+                self._attrs = o._attrs.copy()
                 result.append(o)
             else:
-                result.append(Edge(o, forward=forward, reverse=reverse,
-                                   color=self.color, label=self.label, style=self.style))
+                result.append(Edge(o, forward=forward, reverse=reverse, **self._attrs))
         return result
 
     def connect(self, other: Union["Node", "Edge", List["Node"]]):
@@ -471,9 +468,7 @@ class Edge:
                 self.node.connect(node, self)
             return other
         elif isinstance(other, Edge):
-            self.label = other.label
-            self.color = other.color
-            self.style = other.style
+            self._attrs = other._attrs.copy()
             return self
         else:
             if self.node is not None:
@@ -482,23 +477,17 @@ class Edge:
                 self.node = other
                 return self
 
-    def to_dot(self) -> Dict:
-        dot = {}
+    def attrs(self) -> Dict:
         if self.forward and self.reverse:
-            dot['dir'] = 'both'
+            direction = 'both'
         elif self.forward:
-            dot['dir'] = 'forward'
+            direction = 'forward'
         elif self.reverse:
-            dot['dir'] = 'back'
+            direction = 'back'
         else:
-            dot['dir'] = 'none'
-        if self.label:
-            dot['label'] = self.label
-        if self.color:
-            dot['color'] = self.color
-        if self.style:
-            dot['style'] = self.style
-        return dot
+            direction = 'none'
+
+        return {**self._attrs, 'dir': direction}
 
 
 Group = Cluster

docs/getting-started/examples.md

@@ -213,6 +213,49 @@ with Diagram("Advanced Web Service with On-Premise", show=False):
 
 ![advanced web service with on-premise diagram](/img/advanced_web_service_with_on-premise.png)
 
+## Advanced Web Service with On-Premise (with colors and labels)
+
+```python
+from diagrams import Cluster, Diagram, Edge
+from diagrams.onprem.analytics import Spark
+from diagrams.onprem.compute import Server
+from diagrams.onprem.database import PostgreSQL
+from diagrams.onprem.inmemory import Redis
+from diagrams.onprem.logging import Fluentd
+from diagrams.onprem.monitoring import Grafana, Prometheus
+from diagrams.onprem.network import Nginx
+from diagrams.onprem.queue import Kafka
+
+with Diagram(name="Advanced Web Service with On-Premise (colored)", show=False):
+    ingress = Nginx("ingress")
+
+    metrics = Prometheus("metric")
+    metrics << Edge(color="firebrick", style="dashed") << Grafana("monitoring")
+
+    with Cluster("Service Cluster"):
+        grpcsvc = [
+            Server("grpc1"),
+            Server("grpc2"),
+            Server("grpc3")]
+
+    with Cluster("Sessions HA"):
+        master = Redis("session")
+        master - Edge(color="brown", style="dashed") - Redis("replica") << Edge(label="collect") << metrics
+        grpcsvc >> Edge(color="brown") >> master
+
+    with Cluster("Database HA"):
+        master = PostgreSQL("users")
+        master - Edge(color="brown", style="dotted") - PostgreSQL("slave") << Edge(label="collect") << metrics
+        grpcsvc >> Edge(color="black") >> master
+
+    aggregator = Fluentd("logging")
+    aggregator >> Edge(label="parse") >> Kafka("stream") >> Edge(color="black", style="bold") >> Spark("analytics")
+
+    ingress >> Edge(color="darkgreen") << grpcsvc >> Edge(color="darkorange") >> aggregator
+```
+
+![advanced web service with on-premise diagram](/img/advanced_web_service_with_on-premise_colored.png)
+
 ## RabbitMQ Consumers with Custom Nodes
 
 ```python
@@ -243,26 +286,3 @@ with Diagram("Broker Consumers", show=False):
 ```
 
 ![rabbitmq consumers diagram](/img/rabbitmq_consumers_diagram.png)
-
-## Diagram with Custom Edges
-
-```python
-from diagrams import Edge
-from diagrams.aws.compute import EC2
-
-# line
-[EC2("node3"), EC2("node4")] - Edge(color='red', label='label1', style='dotted') - EC2("node")
-
-# list of nodes, one directional
-[EC2("node3"), EC2("node4")] >> Edge(color='red', label='label1', style='dotted') >> EC2("node")
-[EC2("node3"), EC2("node4")] << Edge(color='green', label='label2', style='dashed') << EC2("node")
-
-# both directional
-EC2("node") << Edge(color='blue', label='label3', style='bold') >> EC2("node")
-
-# loop
-node = EC2("node")
-node >> Edge(color='pink', label='label4', style='solid') << node
-```
-
-![custom edges diagram](/img/custom_edges_diagram.png)