[hma] add endpoint to delete a content_signal from a bank (#1632)

hasher-matcher-actioner/src/OpenMediaMatch/blueprints/curation.py

@@ -212,6 +212,20 @@ def _bank_add_signals(
     }
 
 
+@bp.route("/bank/<bank_name>/content/<content_id>", methods=["DELETE"])
+def bank_delete_content(bank_name: str, content_id: int):
+    """
+    Remove a signal from a bank.
+    """
+    storage = persistence.get_storage()
+    bank = storage.get_bank(bank_name)
+    if not bank:
+        abort(404, f"bank '{bank_name}' not found")
+
+    count = storage.bank_remove_content(bank.name, content_id)
+    return {"deleted": count}
+
+
 @bp.route("/bank/<bank_name>/signal", methods=["POST"])
 def bank_add_as_signals(bank_name: str):
     """

hasher-matcher-actioner/src/OpenMediaMatch/storage/interface.py

@@ -511,7 +511,7 @@ def bank_add_content(
         """
 
     @abc.abstractmethod
-    def bank_remove_content(self, bank_name: str, content_id: int) -> None:
+    def bank_remove_content(self, bank_name: str, content_id: int) -> int:
         """Remove content from bank by id"""
 
     @abc.abstractmethod

hasher-matcher-actioner/src/OpenMediaMatch/storage/mocked.py

@@ -190,7 +190,7 @@ def bank_add_content(
         # TODO
         raise Exception("Not implemented")
 
-    def bank_remove_content(self, bank_name: str, content_id: int) -> None:
+    def bank_remove_content(self, bank_name: str, content_id: int) -> int:
         # TODO
         raise Exception("Not implemented")
 

hasher-matcher-actioner/src/OpenMediaMatch/storage/postgres/impl.py

@@ -566,11 +566,13 @@ def bank_add_content(
         sesh.commit()
         return content.id
 
-    def bank_remove_content(self, bank_name: str, content_id: int) -> None:
-        database.db.session.execute(
+    def bank_remove_content(self, bank_name: str, content_id: int) -> int:
+        # TODO: throw an exception if deleting imported content
+        result = database.db.session.execute(
             delete(database.BankContent).where(database.BankContent.id == content_id)
         )
         database.db.session.commit()
+        return result.rowcount
 
     def get_current_index_build_target(
         self, signal_type: t.Type[SignalType]

hasher-matcher-actioner/src/OpenMediaMatch/tests/test_api.py

@@ -154,6 +154,19 @@ def test_banks_add_hash(client: FlaskClient):
     }
 
 
+def test_banks_delete_hash(client: FlaskClient):
+    bank_name = "NEW_BANK"
+    image_url = "https://github.com/facebook/ThreatExchange/blob/main/pdq/data/bridge-mods/aaa-orig.jpg?raw=true"
+
+    create_bank(client, bank_name)
+    add_hash_to_bank(client, bank_name, image_url, 1)
+
+    post_response = client.delete(f"/c/bank/{bank_name}/content/1")
+
+    assert post_response.status_code == 200
+    assert post_response.json == {"deleted": 1}
+
+
 def test_banks_add_metadata(client: FlaskClient):
     bank_name = "NEW_BANK"
     create_bank(client, bank_name)