fix: improve CSV path handling and error handling in substrait example

examples/substrait.py

@@ -15,35 +15,63 @@
 # specific language governing permissions and limitations
 # under the License.
 
+import os
 from datafusion import SessionContext
 from datafusion import substrait as ss
 
 # Create a DataFusion context
 ctx = SessionContext()
 
-# Register table with context
-ctx.register_csv("aggregate_test_data", "./testing/data/csv/aggregate_test_100.csv")
+# Get the directory of this script
+current_dir = os.path.dirname(os.path.abspath(__file__))
+csv_path = os.path.join(current_dir, "testing", "data", "csv", "aggregate_test_100.csv")
 
-substrait_plan = ss.Serde.serialize_to_plan("SELECT * FROM aggregate_test_data", ctx)
-# type(substrait_plan) -> <class 'datafusion.substrait.plan'>
+try:
+    # Register table with context using cross-platform path
+    ctx.register_csv("aggregate_test_data", csv_path)
+except Exception as e:
+    print(f"Error registering CSV file: {e}")
+    print(f"Please ensure the CSV file exists at: {csv_path}")
+    raise
 
-# Encode it to bytes
-substrait_bytes = substrait_plan.encode()
-# type(substrait_bytes) -> <class 'bytes'>, at this point the bytes can be distributed to file, network, etc safely
-# where they could subsequently be deserialized on the receiving end.
+# Create a Substrait plan from SQL query
+try:
+    substrait_plan = ss.Serde.serialize_to_plan("SELECT * FROM aggregate_test_data", ctx)
+except Exception as e:
+    print(f"Error creating Substrait plan: {e}")
+    raise
 
-# Alternative serialization approaches
-# type(substrait_bytes) -> <class 'bytes'>, at this point the bytes can be distributed to file, network, etc safely
-# where they could subsequently be deserialized on the receiving end.
-substrait_bytes = ss.Serde.serialize_bytes("SELECT * FROM aggregate_test_data", ctx)
+# Encode the plan to bytes
+try:
+    substrait_bytes = substrait_plan.encode()
+except Exception as e:
+    print(f"Error encoding Substrait plan: {e}")
+    raise
 
-# Imagine here bytes would be read from network, file, etc ... for example brevity this is omitted and variable is simply reused
-# type(substrait_plan) -> <class 'datafusion.substrait.plan'>
-substrait_plan = ss.Serde.deserialize_bytes(substrait_bytes)
+# Alternative serialization approach
+try:
+    substrait_bytes = ss.Serde.serialize_bytes("SELECT * FROM aggregate_test_data", ctx)
+except Exception as e:
+    print(f"Error in alternative serialization: {e}")
+    raise
 
-# type(df_logical_plan) -> <class 'substrait.LogicalPlan'>
-df_logical_plan = ss.Consumer.from_substrait_plan(ctx, substrait_plan)
+# Deserialize the bytes back to a Substrait plan
+try:
+    substrait_plan = ss.Serde.deserialize_bytes(substrait_bytes)
+except Exception as e:
+    print(f"Error deserializing Substrait plan: {e}")
+    raise
 
-# Back to Substrait Plan just for demonstration purposes
-# type(substrait_plan) -> <class 'datafusion.substrait.plan'>
-substrait_plan = ss.Producer.to_substrait_plan(df_logical_plan, ctx)
+# Convert Substrait plan to DataFusion logical plan
+try:
+    df_logical_plan = ss.Consumer.from_substrait_plan(ctx, substrait_plan)
+except Exception as e:
+    print(f"Error converting to logical plan: {e}")
+    raise
+
+# Convert back to Substrait plan for demonstration
+try:
+    substrait_plan = ss.Producer.to_substrait_plan(df_logical_plan, ctx)
+except Exception as e:
+    print(f"Error converting back to Substrait plan: {e}")
+    raise