Add dataset class to represent export data

backend/data_export/pipeline/dataset.py

@@ -0,0 +1,22 @@
+from typing import Any, Dict, Iterator, Type
+
+import pandas as pd
+from django.db.models.query import QuerySet
+
+from .labels import Labels
+from examples.models import Example
+
+
+class Dataset:
+    def __init__(self, examples: QuerySet[Example], user, label_collection_class: Type[Labels], confirmed_only=False):
+        if confirmed_only:
+            examples = examples.filter(states__confirmed_by=user)
+        self.examples = examples
+        self.labels = label_collection_class(examples, user)
+
+    def __iter__(self) -> Iterator[Dict[str, Any]]:
+        for example in self.examples:
+            yield {"id": example.id, "data": example.text, **example.meta, **self.labels.find_by(example.id)}
+
+    def to_pandas(self) -> pd.DataFrame:
+        return pd.DataFrame(self)