fix: truncate "params" column on vertex_build table to prevent memory…

… heap on database (langflow-ai#4118)

* ✨ (model.py): add new method `serialize_params` to serialize parameters data in VertexBuildBase class

* 🐛 (util_strings.py): fix truncation logic to correctly handle long strings by truncating them with ellipsis if they exceed the maximum length

* ✅ (test_truncate_long_strings.py): add unit tests for the truncate_long_strings function to ensure it works correctly with various input scenarios

* ✅ (test_truncate_long_strings_on_objects.py): update test assertion message to reflect the expected behavior of the function

src/backend/base/langflow/services/database/models/vertex_builds/model.py

@@ -49,6 +49,10 @@ def serialize_data(self, data: dict) -> dict:
     def serialize_artifacts(self, data) -> dict:
         return truncate_long_strings(data)
 
+    @field_serializer("params")
+    def serialize_params(self, data) -> dict:
+        return truncate_long_strings(data)
+
 
 class VertexBuildTable(VertexBuildBase, table=True):  # type: ignore[call-arg]
     __tablename__ = "vertex_build"

src/backend/base/langflow/utils/util_strings.py

@@ -9,7 +9,12 @@ def truncate_long_strings(data, max_length=None):
     if max_length is None:
         max_length = constants.MAX_TEXT_LENGTH
 
-    if max_length < 0 or not isinstance(data, dict | list):
+    if max_length < 0:
+        return data
+
+    if not isinstance(data, dict | list):
+        if isinstance(data, str) and len(data) > max_length:
+            return data[:max_length] + "..."
         return data
 
     if isinstance(data, dict):

src/backend/tests/unit/utils/test_truncate_long_strings.py

@@ -0,0 +1,54 @@
+import pytest
+from langflow.utils.util_strings import truncate_long_strings
+
+
+@pytest.mark.parametrize(
+    "input_data, max_length, expected",
+    [
+        # Test case 1: String shorter than max_length
+        ("short string", 20, "short string"),
+        # Test case 2: String exactly at max_length
+        ("exact", 5, "exact"),
+        # Test case 3: String longer than max_length
+        ("long string", 7, "long st..."),
+        # Test case 4: Empty string
+        ("", 5, ""),
+        # Test case 5: Single character string
+        ("a", 1, "a"),
+        # Test case 6: Unicode string
+        ("こんにちは", 3, "こんに..."),
+        # Test case 7: Integer input
+        (12345, 3, 12345),
+        # Test case 8: Float input
+        (3.14159, 4, 3.14159),
+        # Test case 9: Boolean input
+        (True, 2, True),
+        # Test case 10: None input
+        (None, 5, None),
+        # Test case 11: Very long string
+        ("a" * 1000, 10, "a" * 10 + "..."),
+    ],
+)
+def test_truncate_long_strings_non_dict_list(input_data, max_length, expected):
+    result = truncate_long_strings(input_data, max_length)
+    assert result == expected
+
+
+# Test for max_length of 0
+def test_truncate_long_strings_zero_max_length():
+    assert truncate_long_strings("any string", 0) == "..."
+
+
+# Test for negative max_length
+def test_truncate_long_strings_negative_max_length():
+    assert truncate_long_strings("any string", -1) == "any string"
+
+
+# Test for None max_length (should use default MAX_TEXT_LENGTH)
+def test_truncate_long_strings_none_max_length():
+    from langflow.utils.constants import MAX_TEXT_LENGTH
+
+    long_string = "a" * (MAX_TEXT_LENGTH + 10)
+    result = truncate_long_strings(long_string, None)
+    assert len(result) == MAX_TEXT_LENGTH + 3  # +3 for "..."
+    assert result == "a" * MAX_TEXT_LENGTH + "..."

src/backend/tests/unit/utils/test_truncate_long_strings_on_objects.py

@@ -74,7 +74,7 @@ def test_truncate_long_strings_in_place_modification():
 def test_truncate_long_strings_invalid_input():
     input_string = "not a dict or list"
     result = truncate_long_strings(input_string, 10)
-    assert result == input_string  # The function should return the input unchanged
+    assert result == "not a dict..."  # The function should truncate the string
 
 
 # Updated test for negative max_length