Fix: Use session state to persist data between button clicks

src/streamlit_app.py

@@ -36,22 +36,26 @@ st.title("Entity Resolution on CSV (Network Graph)")
 st.sidebar.header("Upload CSV for Entity Resolution")
 uploaded_file = st.sidebar.file_uploader("Choose a CSV file", type=["csv"])
 
+# Initialize session state for sample data
+if 'sample_data_df' not in st.session_state:
+    st.session_state.sample_data_df = None
+
 # Generate sample data option
 st.sidebar.markdown("**Or use sample data:**")
 if st.sidebar.button("Use Sample Data"):
     # Create simple sample data for testing
-    sample_data = pd.DataFrame({
+    st.session_state.sample_data_df = pd.DataFrame({
         'first_name': ['John', 'Jon', 'Jane', 'Jain', 'Mike', 'Michael'],
         'last_name': ['Smith', 'Smith', 'Doe', 'Doe', 'Johnson', 'Johnson'], 
         'email_address': ['john.smith@email.com', 'j.smith@gmail.com', 'jane.doe@company.com', 'jdoe@company.com', 'mike.j@work.com', 'michael.johnson@work.com'],
         'phone_number': ['555-0123', '555-0123', '555-0456', '(555) 456-0000', '555-0789', '5550789']
     })
-    csv_buffer = io.StringIO()
-    sample_data.to_csv(csv_buffer, index=False)
-    csv_buffer.seek(0)
-    uploaded_file = csv_buffer
     st.sidebar.success("Sample data loaded!")
 
+# Clear sample data if a file is uploaded
+if uploaded_file is not None:
+    st.session_state.sample_data_df = None
+
 similarity_threshold = st.sidebar.slider(
     "Similarity Threshold",
     min_value=0.0,
@@ -164,10 +168,17 @@ def find_connected_components_manual(nodes, edges):
 # ----------------------
 # LOAD CSV & PROCESS
 # ----------------------
+df = None
 if uploaded_file is not None:
     st.markdown("### Preview of Uploaded CSV Data")
     df = pd.read_csv(uploaded_file)
     st.dataframe(df.head(10))
+elif st.session_state.sample_data_df is not None:
+    st.markdown("### Preview of Sample Data")
+    df = st.session_state.sample_data_df
+    st.dataframe(df.head(10))
+
+if df is not None:
 
     # Provide a "Run Entity Resolution" button
     if st.button("Run Entity Resolution"):