Added support for last() scalar function

neomodel/async_/match.py

@@ -2,7 +2,7 @@
 import re
 from collections import defaultdict
 from dataclasses import dataclass
-from typing import Any, List, Optional
+from typing import Any, List, Optional, Union
 
 from neomodel.async_.core import AsyncStructuredNode, adb
 from neomodel.async_.relationship import AsyncStructuredRel
@@ -944,6 +944,21 @@ def __str__(self):
         return f"collect({self.input_name})"
 
 
+@dataclass
+class ScalarFunction:
+    """Base scalar function class."""
+
+    input_name: Union[str, AggregatingFunction]
+
+
+@dataclass
+class Last(ScalarFunction):
+    """last() function."""
+
+    def __str__(self) -> str:
+        return f"last({str(self.input_name)})"
+
+
 class AsyncNodeSet(AsyncBaseSet):
     """
     A class representing as set of nodes matching common query parameters
@@ -1167,8 +1182,8 @@ def traverse_relations(self, *relation_names, **aliased_relation_names):
     def annotate(self, *vars, **aliased_vars):
         """Annotate node set results with extra variables."""
 
-        def register_extra_var(vardef, varname: str = None):
-            if isinstance(vardef, AggregatingFunction):
+        def register_extra_var(vardef, varname: Union[str, None] = None):
+            if isinstance(vardef, (AggregatingFunction, ScalarFunction)):
                 self._extra_results[varname if varname else vardef.input_name] = vardef
             else:
                 raise NotImplementedError

neomodel/sync_/match.py

@@ -2,7 +2,7 @@
 import re
 from collections import defaultdict
 from dataclasses import dataclass
-from typing import Any, List, Optional
+from typing import Any, List, Optional, Union
 
 from neomodel.exceptions import MultipleNodesReturned
 from neomodel.match_q import Q, QBase
@@ -942,6 +942,21 @@ def __str__(self):
         return f"collect({self.input_name})"
 
 
+@dataclass
+class ScalarFunction:
+    """Base scalar function class."""
+
+    input_name: Union[str, AggregatingFunction]
+
+
+@dataclass
+class Last(ScalarFunction):
+    """last() function."""
+
+    def __str__(self) -> str:
+        return f"last({str(self.input_name)})"
+
+
 class NodeSet(BaseSet):
     """
     A class representing as set of nodes matching common query parameters
@@ -1165,8 +1180,8 @@ def traverse_relations(self, *relation_names, **aliased_relation_names):
     def annotate(self, *vars, **aliased_vars):
         """Annotate node set results with extra variables."""
 
-        def register_extra_var(vardef, varname: str = None):
-            if isinstance(vardef, AggregatingFunction):
+        def register_extra_var(vardef, varname: Union[str, None] = None):
+            if isinstance(vardef, (AggregatingFunction, ScalarFunction)):
                 self._extra_results[varname if varname else vardef.input_name] = vardef
             else:
                 raise NotImplementedError

test/async_/test_match_api.py

@@ -24,6 +24,7 @@
     AsyncQueryBuilder,
     AsyncTraversal,
     Collect,
+    Last,
     Optional,
 )
 from neomodel.exceptions import MultipleNodesReturned, RelationshipClassNotDefined
@@ -732,13 +733,14 @@ async def test_subquery():
 
     result = await Coffee.nodes.subquery(
         Coffee.nodes.traverse_relations(suppliers="suppliers").annotate(
-            supps=Collect("suppliers")
+            supps=Last(Collect("suppliers"))
         ),
         ["supps"],
     )
     result = await result.all()
     assert len(result) == 1
-    assert len(result[0][0][0]) == 2
+    assert len(result[0]) == 2
+    assert result[0][0] == supplier1
 
     with raises(
         RuntimeError,

test/sync_/test_match_api.py

@@ -20,7 +20,14 @@
 )
 from neomodel._async_compat.util import Util
 from neomodel.exceptions import MultipleNodesReturned, RelationshipClassNotDefined
-from neomodel.sync_.match import Collect, NodeSet, Optional, QueryBuilder, Traversal
+from neomodel.sync_.match import (
+    Collect,
+    Last,
+    NodeSet,
+    Optional,
+    QueryBuilder,
+    Traversal,
+)
 
 
 class SupplierRel(StructuredRel):
@@ -720,13 +727,14 @@ def test_subquery():
 
     result = Coffee.nodes.subquery(
         Coffee.nodes.traverse_relations(suppliers="suppliers").annotate(
-            supps=Collect("suppliers")
+            supps=Last(Collect("suppliers"))
         ),
         ["supps"],
     )
     result = result.all()
     assert len(result) == 1
-    assert len(result[0][0][0]) == 2
+    assert len(result[0]) == 2
+    assert result[0][0] == supplier1
 
     with raises(
         RuntimeError,