Remove custom shell output formatting to match Python script behavior (#9)

Author: joshuadavidthomas

CHANGELOG.md

@@ -18,6 +18,14 @@ and this project attempts to adhere to [Semantic Versioning](https://semver.org/
 
 ## [Unreleased]
 
+### Changed
+
+- Removed custom formatting for QuerySets and iterables in shell output. QuerySets now display as `<QuerySet [...]>` and lists show their standard `repr()` instead of truncated displays with "... and X more items". This makes output consistent with standard Django/Python shell behavior and should hopefully not confused the robots.
+
+### Fixed
+
+- Django shell no longer shows `None` after print statements. Expression values are now only displayed when code doesn't print output, matching Python script execution behavior.
+
 ## [0.2.0]
 
 ### Added

src/mcp_django_shell/shell.py

@@ -202,33 +202,11 @@ def __post_init__(self):
 
     @property
     def output(self) -> str:
-        parts = []
-
         if self.stdout:
-            parts.append(self.stdout.strip())
-
-        if self.value is not None:
-            if hasattr(self.value, "__iter__") and not isinstance(
-                self.value, str | dict
-            ):
-                # Format querysets and lists nicely
-                try:
-                    items = list(self.value)
-                    match len(items):
-                        case 0:
-                            parts.append("Empty queryset/list")
-                        case n if n > 10:
-                            parts.extend(repr(item) for item in items[:10])
-                            parts.append(f"... and {n - 10} more items")
-                        case _:
-                            parts.extend(repr(item) for item in items)
-                except Exception:
-                    # If iteration fails, fall back to repr
-                    parts.append(repr(self.value))
-            else:
-                parts.append(repr(self.value))
-
-        return "\n".join(parts)
+            return self.stdout.rstrip()
+        elif self.value is not None:
+            return repr(self.value)
+        return ""
 
 
 @dataclass
@@ -294,7 +272,12 @@ def output(self) -> str:
             line for line in tb_lines if "mcp_django_shell" not in line
         )
 
-        return f"{error_type}: {self.exception}\n\nTraceback:\n{relevant_tb}"
+        error_output = f"{error_type}: {self.exception}\n\nTraceback:\n{relevant_tb}"
+
+        if self.stdout:
+            return f"{self.stdout.rstrip()}\n{error_output}"
+
+        return error_output
 
 
 Result = ExpressionResult | StatementResult | ErrorResult

tests/test_shell.py

@@ -194,64 +194,100 @@ async def test_async_execute_returns_result(self):
         assert result.value == 4
 
 
-@pytest.mark.django_db
 class TestResultOutput:
-    def test_format_large_queryset_truncates_at_10(self, shell):
-        for i in range(15):
-            AModel.objects.create(name=f"Item {i}", value=i)
+    def test_expression_with_value_no_stdout(self, shell):
+        result = shell._execute("42")
+        assert isinstance(result, ExpressionResult)
+        assert result.output == "42"
 
-        shell._execute("from tests.models import AModel")
+    def test_expression_with_none_no_stdout(self, shell):
+        result = shell._execute("None")
+        assert isinstance(result, ExpressionResult)
+        assert result.output == ""
 
-        result = shell._execute("AModel.objects.all()")
+    def test_expression_with_stdout_and_value(self, shell):
+        code = """\
+print('hello')
+42
+"""
+        result = shell._execute(code.strip())
+        assert isinstance(result, ExpressionResult)
+        assert result.output == "hello"  # No "42" shown
 
+    def test_expression_with_stdout_and_none(self, shell):
+        result = shell._execute("print('hello')")
         assert isinstance(result, ExpressionResult)
-        assert "... and 5 more items" in result.output
-        assert "Item 0" in result.output
-        # Should show first 10, not the last 5
-        assert "Item 9" in result.output
-        assert "Item 14" not in result.output
+        assert result.output == "hello"  # No "None" shown
+
+    def test_multiline_ending_with_print(self, shell):
+        code = """\
+x = 5
+y = 10
+print(f"Sum: {x + y}")
+"""
+        result = shell._execute(code.strip())
+        assert isinstance(result, ExpressionResult)
+        assert result.output == "Sum: 15"  # No "None" appended
+
+    def test_function_returning_none(self, shell):
+        code = """\
+def foo():
+    x = 2
+foo()
+"""
+        result = shell._execute(code.strip())
+        assert isinstance(result, ExpressionResult)
+        assert result.output == ""
 
-    def test_format_small_queryset_shows_all(self, shell):
-        for i in range(5):
+    @pytest.mark.django_db
+    def test_queryset_shows_standard_repr(self, shell):
+        for i in range(3):
             AModel.objects.create(name=f"Item {i}", value=i)
 
         shell._execute("from tests.models import AModel")
-
         result = shell._execute("AModel.objects.all()")
 
         assert isinstance(result, ExpressionResult)
-        # Should show all items, no truncation message for <10 items
+        assert result.output.startswith("<QuerySet [<AModel:")
         assert "Item 0" in result.output
-        assert "Item 4" in result.output
-        assert "... and" not in result.output
-
-    def test_format_empty_queryset_shows_message(self, shell):
-        shell._execute("from tests.models import AModel")
+        assert "Item 2" in result.output
 
-        result = shell._execute("AModel.objects.none()")
+    def test_statement_with_stdout(self, shell):
+        result = shell._execute("x = 5; print(x)")
+        assert isinstance(result, StatementResult)
+        assert result.output == "5\n"  # print adds a newline
 
-        assert isinstance(result, ExpressionResult)
-        assert "Empty queryset/list" in result.output
+    def test_statement_no_stdout(self, shell):
+        result = shell._execute("x = 5")
+        assert isinstance(result, StatementResult)
+        assert result.output == "OK"
 
-    def test_format_empty_list_shows_message(self, shell):
-        """Integration test for empty list formatting."""
-        result = shell._execute("[]")
+    def test_error_with_stdout(self, shell):
+        code = """\
+print("Starting...")
+print("Processing...")
+1 / 0
+"""
+        result = shell._execute(code.strip())
+        assert isinstance(result, ErrorResult)
+        assert "Starting..." in result.output
+        assert "Processing..." in result.output
+        assert "ZeroDivisionError" in result.output
+        # Stdout should come before the error
+        assert result.output.index("Starting...") < result.output.index(
+            "ZeroDivisionError"
+        )
 
-        assert isinstance(result, ExpressionResult)
-        assert "Empty queryset/list" in result.output
-
-    def test_format_bad_iterable_uses_repr(self, shell):
-        result = shell._execute("""\
-class BadIterable:
-    def __iter__(self):
-        raise RuntimeError("Can't iterate")
-    def __repr__(self):
-        return "BadIterable()"
-BadIterable()
-""")
+    def test_error_no_stdout(self, shell):
+        result = shell._execute("1 / 0")
+        assert isinstance(result, ErrorResult)
+        assert "ZeroDivisionError" in result.output
+        assert "Traceback:" in result.output
 
-        assert isinstance(result, ExpressionResult)
-        assert "BadIterable()" in result.output
+    def test_error_filters_framework_lines(self, shell):
+        result = shell._execute("1 / 0")
+        assert isinstance(result, ErrorResult)
+        assert "mcp_django_shell" not in result.output
 
 
 class TestShellState: