fix: handle connection failures (#110)

Author: Integer-Ctrl

databusclient/api/download.py

@@ -344,6 +344,21 @@ class DownloadAuthError(Exception):
     """Raised when an authorization problem occurs during download."""
 
 
+def format_download_connection_error(error: requests.exceptions.ConnectionError | requests.exceptions.Timeout) -> str:
+    """Return a concise message for a failed download connection."""
+    request = getattr(error, "request", None)
+    request_url = getattr(request, "url", "")
+    host = urlparse(request_url).hostname or "the remote server"
+
+    if isinstance(error, requests.exceptions.Timeout):
+        return f"Could not connect to {host}: the request timed out."
+
+    return (
+        f"Could not connect to {host}. "
+        "Check the server address and your network connection."
+    )
+
+
 def _extract_checksums_from_jsonld(json_str: str) -> dict:
     """
     Parse a JSON-LD string and return a mapping of file URI (and @id) -> checksum.

databusclient/cli.py

@@ -4,10 +4,11 @@
 from typing import List
 
 import click
+import requests
 
 import databusclient.api.deploy as api_deploy
 from databusclient.api.delete import delete as api_delete
-from databusclient.api.download import download as api_download, DownloadAuthError
+from databusclient.api.download import DownloadAuthError, download as api_download, format_download_connection_error
 from databusclient.manifest.context import ManifestContext
 from databusclient.manifest.writer import ManifestWriter
 from databusclient.manifest.replay import ManifestReplayError, replay_manifest, load_manifest
@@ -398,6 +399,10 @@ def download(
         if manifest_context:
             manifest_context.record_operation_error(e)
         raise click.ClickException(str(e))
+    except (requests.exceptions.ConnectionError, requests.exceptions.Timeout) as e:
+        if manifest_context:
+            manifest_context.record_operation_error(e)
+        raise click.ClickException(format_download_connection_error(e))
     except ValueError as e:
         if manifest_context:
             manifest_context.record_operation_error(e)

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "databusclient"
-version = "1.2.0"
+version = "1.2.1"
 description = "A simple client for submitting, downloading, and deleting data on the DBpedia Databus"
 authors = ["DBpedia Association"]
 license = "Apache-2.0 License"

tests/test_download.py

@@ -3,6 +3,7 @@
 import bz2
 
 import pytest
+import requests
 from click.testing import CliRunner
 
 from databusclient.api.download import download as api_download
@@ -196,6 +197,46 @@ def fake_download(**kwargs):
     assert manifest["dbus:replayParams"]["graph_mode"] == "download-url"
 
 
+def test_cli_reports_redirected_download_timeout_without_traceback(monkeypatch):
+    request = requests.Request(
+        "HEAD", "https://data.dbpedia.org/repo/example/data.ttl"
+    ).prepare()
+
+    def timeout(**_kwargs):
+        raise requests.exceptions.ConnectTimeout(request=request)
+
+    monkeypatch.setattr("databusclient.cli.api_download", timeout)
+
+    result = CliRunner().invoke(
+        app, ["download", "https://databus.dbpedia.org/example/data.ttl"]
+    )
+
+    assert result.exit_code == 1
+    assert (
+        "Error: Could not connect to data.dbpedia.org: "
+        "the request timed out."
+    ) in result.output
+    assert "Traceback" not in result.output
+
+
+def test_cli_reports_connection_failure_without_traceback(monkeypatch):
+    request = requests.Request("GET", "https://files.example.org/data.ttl").prepare()
+
+    def connection_error(**_kwargs):
+        raise requests.exceptions.ConnectionError(request=request)
+
+    monkeypatch.setattr("databusclient.cli.api_download", connection_error)
+
+    result = CliRunner().invoke(
+        app, ["download", "https://databus.dbpedia.org/example/data.ttl"]
+    )
+
+    assert result.exit_code == 1
+    assert "Error: Could not connect to files.example.org." in result.output
+    assert "Check the server address and your network connection." in result.output
+    assert "Traceback" not in result.output
+
+
 def test_converted_output_gets_graph_sidecar_at_final_path(monkeypatch, tmp_path):
     import databusclient.api.download as dl