Add t1_name/t2_name to rename t1/t2 labels in tree view repr

AUTHORS.md

@@ -89,3 +89,4 @@ Authors in order of the timeline of their contributions:
 - [akshat62](https://github.com/akshat62) for adding wildcard/glob pattern support for `exclude_paths` and `include_paths`.
 - [mgorny](https://github.com/mgorny) for adding missing files to sdist and removing obsolete `MANIFEST.in`.
 - [Sanjays2402](https://github.com/Sanjays2402) for fixing missing type changes between equal-comparing list items (e.g. `[2]` vs `[2.0]`).
+- [ChrisJr404](https://github.com/ChrisJr404) for adding `t1_name`/`t2_name` to rename the tree view's `t1`/`t2` labels.

CHANGELOG.md

@@ -1,6 +1,7 @@
 # DeepDiff Change log
 
 - Unreleased
+    - Added `t1_name` and `t2_name` parameters to rename the `t1`/`t2` labels shown in the tree view's string representation, e.g. `<root['a'] before:1, after:2>` (issue #531)
     - Fixed missing type changes between equal-comparing items inside ordered iterables, e.g. `DeepDiff([2], [2.0])` now reports the `int` → `float` change like `DeepDiff(2, 2.0)` and `DeepDiff({'a': 2}, {'a': 2.0})` already do (issue #605).
 
 - v9-1-0

deepdiff/diff.py

@@ -201,6 +201,8 @@ def __init__(self,
                  progress_logger: Callable[[str], None]=logger.info,
                  report_repetition: bool=False,
                  significant_digits: Optional[int]=None,
+                 t1_name: str="t1",
+                 t2_name: str="t2",
                  threshold_to_diff_deeper: float = 0.33,
                  truncate_datetime: Optional[str]=None,
                  use_enum_value: bool=False,
@@ -223,6 +225,7 @@ def __init__(self,
                 "number_format_notation, exclude_paths, include_paths, exclude_types, exclude_regex_paths, ignore_type_in_groups, "
                 "ignore_string_type_changes, ignore_numeric_type_changes, ignore_type_subclasses, ignore_uuid_types, truncate_datetime, "
                 "ignore_private_variables, ignore_nan_inequality, number_to_string_func, verbose_level, "
+                "t1_name, t2_name, "
                 "view, hasher, hashes, max_passes, max_diffs, zip_ordered_iterables, "
                 "cutoff_distance_for_pairs, cutoff_intersection_for_pairs, log_frequency_in_sec, cache_size, "
                 "cache_tuning_sample_size, get_deep_distance, group_by, group_by_sort_key, cache_purge_level, log_stacktrace,"
@@ -233,6 +236,10 @@ def __init__(self,
 
         if _parameters:
             self.__dict__.update(_parameters)
+            # Backward compatibility: t1_name/t2_name may be absent from an
+            # externally-supplied _parameters dict, so fall back to the defaults.
+            self.t1_name = _parameters.get('t1_name', t1_name)
+            self.t2_name = _parameters.get('t2_name', t2_name)
         else:
             self.custom_operators = custom_operators or []
             self.ignore_order = ignore_order
@@ -309,6 +316,8 @@ def _group_by_sort_key(x):
                 self.verbose_level = verbose_level
             else:
                 raise ValueError(VERBOSE_LEVEL_RANGE_MSG)
+            self.t1_name = t1_name
+            self.t2_name = t2_name
             if cache_purge_level not in {0, 1, 2}:
                 raise ValueError(PURGE_LEVEL_RANGE_MSG)
             self.view = view
@@ -400,7 +409,8 @@ def _group_by_sort_key(x):
         self.t2 = t2
 
         try:
-            root = DiffLevel(t1, t2, verbose_level=self.verbose_level)
+            root = DiffLevel(t1, t2, verbose_level=self.verbose_level,
+                             t1_name=self.t1_name, t2_name=self.t2_name)
             # _original_type is only used to pass the original type of the data. Currently only used for numpy arrays.
             # The reason is that we convert the numpy array to python list and then later for distance calculations
             # we convert only the the last dimension of it into numpy arrays.

deepdiff/docstrings/authors.rst

@@ -130,6 +130,7 @@ Authors in order of the timeline of their contributions:
 - `akshat62 <https://github.com/akshat62>`__ for adding Fraction numeric support.
 - `akshat62 <https://github.com/akshat62>`__ for adding wildcard/glob pattern support for ``exclude_paths`` and ``include_paths``.
 - `mgorny <https://github.com/mgorny>`__ for adding missing files to sdist and removing obsolete ``MANIFEST.in``.
+- `ChrisJr404 <https://github.com/ChrisJr404>`__ for adding ``t1_name``/``t2_name`` to rename the tree view's ``t1``/``t2`` labels.
 
 
 .. _Sep Dehpour (Seperman): http://www.zepworks.com

deepdiff/docstrings/diff_doc.rst

@@ -199,6 +199,12 @@ significant_digits : int >= 0, default=None
 truncate_datetime: string, default = None
     :ref:`truncate_datetime_label` can take value one of 'second', 'minute', 'hour', 'day' and truncate with this value datetime objects before hashing it
 
+t1_name: string, default = "t1"
+    The label used for the first object when a level of the tree view is represented as a string. For example, passing ``t1_name="before"`` turns ``<root['a'] t1:1, t2:2>`` into ``<root['a'] before:1, t2:2>``. This only affects the ``repr`` of tree view levels; it has no effect on the text view or the comparison itself.
+
+t2_name: string, default = "t2"
+    The label used for the second object when a level of the tree view is represented as a string. See ``t1_name`` above.
+
 threshold_to_diff_deeper: float, default = 0.33
     :ref:`threshold_to_diff_deeper_label` is a number between 0 and 1. When comparing dictionaries that have a small intersection of keys, we will report the dictionary as a new_value instead of reporting individual keys changed. If you set it to zero, you get the same results as DeepDiff 7.0.1 and earlier, which means this feature is disabled. The new default is 0.33 which means if less that one third of keys between dictionaries intersect, report it as a new object.
 

deepdiff/docstrings/view.rst

@@ -110,6 +110,15 @@ Value of an item has changed (Tree View)
     >>> changed.up
     <root t1:{1: 1, 2: 2,...}, t2:{1: 1, 2: 4,...}>
 
+Custom labels for the compared objects (Tree View)
+    The ``t1`` and ``t2`` labels shown in the string representation can be renamed via the ``t1_name`` and ``t2_name`` parameters. This is handy when the two objects have meaningful roles such as "before" and "after".
+
+    >>> t1 = {1:1, 2:2, 3:3}
+    >>> t2 = {1:1, 2:4, 3:3}
+    >>> ddiff = DeepDiff(t1, t2, view='tree', t1_name="before", t2_name="after")
+    >>> ddiff
+    {'values_changed': [<root[2] before:2, after:4>]}
+
 List difference (Tree View)
     >>> t1 = {1:1, 2:2, 3:3, 4:{"a":"hello", "b":[1, 2, 3, 4]}}
     >>> t2 = {1:1, 2:2, 3:3, 4:{"a":"hello", "b":[1, 2]}}

deepdiff/model.py

@@ -533,7 +533,9 @@ def __init__(self,
                  child_rel1: Optional['ChildRelationship'] = None,
                  child_rel2: Optional['ChildRelationship'] = None,
                  additional: Optional[Dict[str, Any]] = None,
-                 verbose_level: int = 1) -> None:
+                 verbose_level: int = 1,
+                 t1_name: str = "t1",
+                 t2_name: str = "t2") -> None:
         """
         :param child_rel1: Either:
                             - An existing ChildRelationship object describing the "down" relationship for t1; or
@@ -589,6 +591,11 @@ def __init__(self,
 
         self.verbose_level = verbose_level
 
+        # Labels used for t1 and t2 when this level is represented as a string.
+        # Customizable so the tree view repr can use meaningful names, e.g. "before"/"after".
+        self.t1_name = t1_name
+        self.t2_name = t2_name
+
     def __repr__(self) -> str:
         if self.verbose_level:
             from deepdiff.summarize import summarize
@@ -599,7 +606,8 @@ def __repr__(self) -> str:
             else:
                 t1_repr = summarize(self.t1, max_length=35)
                 t2_repr = summarize(self.t2, max_length=35)
-                result = "<{} t1:{}, t2:{}>".format(self.path(), t1_repr, t2_repr)
+                result = "<{} {}:{}, {}:{}>".format(
+                    self.path(), self.t1_name, t1_repr, self.t2_name, t2_repr)
         else:
             result = "<{}>".format(self.path())
         return result
@@ -792,7 +800,8 @@ def create_deeper(self,
         """
         level = self.all_down
         result = DiffLevel(
-            new_t1, new_t2, down=None, up=level, report_type=report_type, verbose_level=self.verbose_level)
+            new_t1, new_t2, down=None, up=level, report_type=report_type, verbose_level=self.verbose_level,
+            t1_name=self.t1_name, t2_name=self.t2_name)
         level.down = result
         level.auto_generate_child_rel(
             klass=child_relationship_class, param=child_relationship_param, param2=child_relationship_param2)

tests/test_model.py

@@ -268,6 +268,24 @@ def test_repr_very_long(self):
             self.lowest.verbose_level = level
         assert item_repr == '<root[1337].a t1:"very long text here, much long...e.", t2:313>'
 
+    def test_repr_custom_t1_t2_names(self):
+        node = DiffLevel(2, 3, t1_name="before", t2_name="after")
+        assert repr(node) == "<root before:2, after:3>"
+
+    def test_custom_t1_t2_names_propagate_to_children(self):
+        diff = DeepDiff({'a': {'b': 1}}, {'a': {'b': 2}}, view='tree',
+                        t1_name='expected', t2_name='actual')
+        level = diff['values_changed'][0]
+        assert repr(level) == "<root['a']['b'] expected:1, actual:2>"
+
+    def test_default_t1_t2_names_unchanged(self):
+        diff = DeepDiff({'a': 1}, {'a': 2}, view='tree')
+        assert repr(diff['values_changed'][0]) == "<root['a'] t1:1, t2:2>"
+
+    def test_custom_t1_t2_names_do_not_affect_text_view(self):
+        diff = DeepDiff({'a': 1}, {'a': 2}, t1_name='before', t2_name='after')
+        assert diff == {'values_changed': {"root['a']": {'new_value': 2, 'old_value': 1}}}
+
     def test_repetition_attribute_and_repr(self):
         t1 = [1, 1]
         t2 = [1]