implemented validator of task name existence on asset document

pype/hosts/standalonepublisher/plugins/publish/validate_task_existence.py

@@ -0,0 +1,57 @@
+import collections
+import pyblish.api
+from avalon import io
+
+
+class ValidateTaskExistence(pyblish.api.ContextPlugin):
+    """Validating tasks on instances are filled and existing."""
+
+    label = "Validate Task Existence"
+    order = pyblish.api.ValidatorOrder
+
+    hosts = ["standalonepublisher"]
+    families = ["render_mov_batch"]
+
+    def process(self, context):
+        asset_names = set()
+        for instance in context:
+            asset_names.add(instance.data["asset"])
+
+        asset_docs = io.find(
+            {
+                "type": "asset",
+                "name": {"$in": list(asset_names)}
+            },
+            {
+                "name": 1,
+                "data.tasks": 1
+            }
+        )
+        tasks_by_asset_names = {}
+        for asset_doc in asset_docs:
+            asset_name = asset_doc["name"]
+            asset_tasks = asset_doc.get("data", {}).get("tasks") or {}
+            tasks_by_asset_names[asset_name] = list(asset_tasks.keys())
+
+        missing_tasks = []
+        for instance in context:
+            asset_name = instance.data["asset"]
+            task_name = instance.data["task"]
+            task_names = tasks_by_asset_names.get(asset_name) or []
+            if task_name and task_name in task_names:
+                continue
+            missing_tasks.append((asset_name, task_name))
+
+        # Everything is OK
+        if not missing_tasks:
+            return
+
+        # Raise an exception
+        msg = "Couldn't find task name/s required for publishing.\n{}"
+        pair_msgs = []
+        for missing_pair in missing_tasks:
+            pair_msgs.append(
+                "Asset: \"{}\" Task: \"{}\"".format(*missing_pair)
+            )
+
+        raise AssertionError(msg.format("\n".join(pair_msgs)))