From cf625a86b464c0487a13806255e389b00994b463 Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Wed, 17 Sep 2025 09:54:10 +0200
Subject: [PATCH 1/3] Make networkx usage in type hints in brackets

---
 flixopt/network_app.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/flixopt/network_app.py b/flixopt/network_app.py
index 957b9e4dd..49a2b2c04 100644
--- a/flixopt/network_app.py
+++ b/flixopt/network_app.py
@@ -7,7 +7,7 @@
 try:
     import dash_cytoscape as cyto
     import dash_daq as daq
-    import networkx
+    import networkx as nx
     from dash import Dash, Input, Output, State, callback_context, dcc, html, no_update
     from werkzeug.serving import make_server
 
@@ -110,7 +110,7 @@ class VisualizationConfig:
     ]
 
 
-def flow_graph(flow_system: FlowSystem) -> networkx.DiGraph:
+def flow_graph(flow_system: FlowSystem) -> 'nx.DiGraph':
     """Convert FlowSystem to NetworkX graph - simplified and more robust"""
     nodes = list(flow_system.components.values()) + list(flow_system.buses.values())
     edges = list(flow_system.flows.values())
@@ -141,7 +141,7 @@ def get_shape(element):
         else:
             return 'rectangle'
 
-    graph = networkx.DiGraph()
+    graph = nx.DiGraph()
 
     # Add nodes with attributes
     for node in nodes:
@@ -168,7 +168,7 @@ def get_shape(element):
     return graph
 
 
-def make_cytoscape_elements(graph: networkx.DiGraph) -> List[Dict[str, Any]]:
+def make_cytoscape_elements(graph: 'nx.DiGraph') -> List[Dict[str, Any]]:
     """Convert NetworkX graph to Cytoscape elements"""
     elements = []
 
@@ -378,7 +378,7 @@ def create_sidebar():
     )
 
 
-def shownetwork(graph: networkx.DiGraph):
+def shownetwork(graph: 'nx.DiGraph'):
     """Main function to create and run the network visualization"""
     if not DASH_CYTOSCAPE_AVAILABLE:
         raise ImportError(f'Required packages not available: {VISUALIZATION_ERROR}')

From 7edd734871061e9bc13a61f8b4706330f8f393c2 Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Sat, 20 Sep 2025 18:07:16 +0200
Subject: [PATCH 2/3] Add extra Exception

---
 flixopt/network_app.py | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/flixopt/network_app.py b/flixopt/network_app.py
index 49a2b2c04..1feb86e70 100644
--- a/flixopt/network_app.py
+++ b/flixopt/network_app.py
@@ -2,7 +2,7 @@
 import logging
 import socket
 import threading
-from typing import Any, Dict, List
+from typing import TYPE_CHECKING, Any, Dict, List
 
 try:
     import dash_cytoscape as cyto
@@ -17,6 +17,9 @@
     DASH_CYTOSCAPE_AVAILABLE = False
     VISUALIZATION_ERROR = str(e)
 
+if TYPE_CHECKING:
+    import networkx as nx
+
 from .components import LinearConverter, Sink, Source, SourceAndSink, Storage
 from .elements import Bus, Component, Flow
 from .flow_system import FlowSystem
@@ -112,6 +115,14 @@ class VisualizationConfig:
 
 def flow_graph(flow_system: FlowSystem) -> 'nx.DiGraph':
     """Convert FlowSystem to NetworkX graph - simplified and more robust"""
+    if not DASH_CYTOSCAPE_AVAILABLE:
+        raise ImportError(
+            'Network visualization requires optional dependencies. '
+            'Install with: pip install flixopt[viz] or '
+            'pip install dash dash-cytoscape networkx werkzeug. '
+            f'Original error: {VISUALIZATION_ERROR}'
+        )
+
     nodes = list(flow_system.components.values()) + list(flow_system.buses.values())
     edges = list(flow_system.flows.values())
 

From f65ee319239e74ea82caad18c237579c8297bc18 Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Sun, 21 Sep 2025 20:46:07 +0200
Subject: [PATCH 3/3] Add Changelog entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 151d9758a..e73ce1521 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -41,6 +41,7 @@ Until here -->
 
 ### Fixed
 - Fix color scheme selection in network_app; color pickers now update when a scheme is selected.
+- Fix error handling in network visualization if networkx is not installed.
 
 ### Known Issues