diff --git a/dataprep/connector/connector.py b/dataprep/connector/connector.py
index 87ac199b9..e2d63a3ca 100644
--- a/dataprep/connector/connector.py
+++ b/dataprep/connector/connector.py
@@ -5,7 +5,7 @@
 import math
 import sys
 from asyncio import as_completed
-from typing import Any, Awaitable, Dict, Optional, Tuple, Union
+from typing import Any, Awaitable, Dict, Optional, Tuple, Union, Set
 from warnings import warn
 
 import pandas as pd
@@ -18,6 +18,8 @@
 from .implicit_database import ImplicitDatabase, ImplicitTable
 from .ref import Ref
 from .schema import (
+    ConfigDef,
+    FieldDef,
     FieldDefUnion,
     OffsetPaginationDef,
     PagePaginationDef,
@@ -112,7 +114,19 @@ async def query(  # pylint: disable=too-many-locals
         **where
             The additional parameters required for the query.
         """
-        allowed_params = self._impdb.tables[table].config.request.params
+        allowed_params: Set[str] = set()
+
+        for key, val in self._impdb.tables[table].config.request.params.items():
+            if isinstance(val, FieldDef):
+                if isinstance(val.from_key, list):
+                    allowed_params.update(val.from_key)
+                elif isinstance(val.from_key, str):
+                    allowed_params.add(val.from_key)
+                else:
+                    allowed_params.add(key)
+            else:
+                allowed_params.add(key)
+
         for key in where:
             if key not in allowed_params:
                 raise InvalidParameterError(key)
@@ -399,20 +413,19 @@ def validate_fields(fields: Dict[str, FieldDefUnion], data: Dict[str, Any]) -> N
     """Check required fields are provided."""
 
     for key, def_ in fields.items():
-        from_key, to_key = key, key
+        to_key = key
 
         if isinstance(def_, bool):
             required = def_
             if required and to_key not in data:
-                raise KeyError(f"'{from_key}' is required but not provided")
+                raise KeyError(f"'{to_key}' is required but not provided")
         elif isinstance(def_, str):
             pass
         else:
             to_key = def_.to_key or to_key
-            from_key = def_.from_key or from_key
             required = def_.required
             if required and to_key not in data:
-                raise KeyError(f"'{from_key}' is required but not provided")
+                raise KeyError(f"'{to_key}' is required but not provided")
 
 
 def populate_field(  # pylint: disable=too-many-branches
@@ -438,7 +451,8 @@ def populate_field(  # pylint: disable=too-many-branches
             template = def_.template
             remove_if_empty = def_.remove_if_empty
             to_key = def_.to_key or to_key
-            from_key = def_.from_key or from_key
+            if not isinstance(def_.from_key, list):
+                from_key = def_.from_key or from_key
 
             if template is None:
                 value = params.get(from_key)
diff --git a/dataprep/connector/schema/defs.py b/dataprep/connector/schema/defs.py
index c9a8acd11..06dadbb75 100644
--- a/dataprep/connector/schema/defs.py
+++ b/dataprep/connector/schema/defs.py
@@ -1,6 +1,8 @@
 """Strong typed schema definition."""
 import http.server
+import json
 import random
+import socket
 import socketserver
 import string
 from base64 import b64encode
@@ -8,15 +10,16 @@
 from pathlib import Path
 from threading import Thread
 from time import time
-from typing import Any, Dict, List, Optional, Union, Set
+from typing import Any, Dict, List, Optional, Set, Union
 from urllib.parse import parse_qs, urlparse
-import socket
-import requests
-from pydantic import Field
+
+from jinja2 import Environment, meta
+from pydantic import Field, root_validator
 
 from ...utils import is_notebook
+from ..errors import InvalidAuthParams, MissingRequiredAuthParams
+from ..utils import Request
 from .base import BaseDef, BaseDefT
-from ..errors import MissingRequiredAuthParams, InvalidAuthParams
 
 # pylint: disable=missing-class-docstring,missing-function-docstring
 FILE_PATH: Path = Path(__file__).resolve().parent
@@ -82,11 +85,35 @@ class TokenPaginationDef(BaseDef):
 
 class FieldDef(BaseDef):
     required: bool
-    from_key: Optional[str]
+    from_key: Union[List[str], str, None]
     to_key: Optional[str]
     template: Optional[str]
     remove_if_empty: bool
 
+    @root_validator(pre=True)
+    def from_key_validation(cls, values):
+        if "template" in values:
+            parsed_content = Environment().parse(values["template"])
+            variables = meta.find_undeclared_variables(parsed_content)  # type: ignore
+
+            from_key = values.get("fromKey")
+            if isinstance(from_key, str):
+                from_key = {from_key}
+            elif from_key is None:
+                from_key = set()
+            elif isinstance(from_key, list):
+                from_key = set(from_key)
+            else:
+                raise NotImplementedError("Unreachable")
+
+            if len(set(variables) - from_key) != 0:
+                raise ValueError(f"template requires {variables} exist in fromKey, got {from_key}")
+        else:
+            if isinstance(values.get("fromKey"), list):
+                raise ValueError("from_key cannot be a list if template is not used.")
+
+        return values
+
 
 FieldDefUnion = Union[FieldDef, bool, str]  # Put bool before str