deprecate dataframe and ExtractedTableAnswer (#8789)

Author: anakin87

Diff for: haystack/dataclasses/answer.py

@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 import io
+import warnings
 from dataclasses import asdict, dataclass, field
 from typing import Any, Dict, List, Optional, Protocol, runtime_checkable
 
@@ -98,6 +99,10 @@ class ExtractedTableAnswer:
     context_cells: List["Cell"] = field(default_factory=list)
     meta: Dict[str, Any] = field(default_factory=dict)
 
+    def __post_init__(self):
+        msg = "The `ExtractedTableAnswer` dataclass is deprecated and will be removed in Haystack 2.11.0."
+        warnings.warn(msg, DeprecationWarning)
+
     @dataclass
     class Cell:
         row: int

Diff for: haystack/dataclasses/document.py

@@ -4,6 +4,7 @@
 
 import hashlib
 import io
+import warnings
 from dataclasses import asdict, dataclass, field, fields
 from typing import Any, Dict, List, Optional
 
@@ -114,6 +115,10 @@ def __post_init__(self):
         # Generate an id only if not explicitly set
         self.id = self.id or self._create_id()
 
+        if self.dataframe is not None:
+            msg = "The `dataframe` field is deprecated and will be removed in Haystack 2.11.0."
+            warnings.warn(msg, DeprecationWarning)
+
     def _create_id(self):
         """
         Creates a hash of the given content that acts as the document's ID.

Diff for: releasenotes/notes/deprecate-dataframe-ExtractedTableAnswer-3d85649a4a7e222f.yaml

@@ -0,0 +1,6 @@
+---
+deprecations:
+  - |
+    The `ExtractedTableAnswer` dataclass and the `dataframe` field in the `Document` dataclass are deprecated and
+    will be removed in Haystack 2.11.0.
+    Check out the GitHub discussion for motivation and details: https://github.com/deepset-ai/haystack/discussions/8688