Introduce allow_parametrize to ValueWrapper

pypika/terms.py

@@ -301,9 +301,12 @@ class Parameter(Term):
     is_aggregate = None
 
     def __init__(self, placeholder: Optional[str] = None, idx: Optional[int] = None) -> None:
-        if not placeholder and not idx:
+        if not placeholder and idx is None:
             raise ValueError("Must provide either a placeholder or an idx")
 
+        if idx is not None and idx < 1:
+            raise ValueError("idx must start at 1")
+
         if placeholder and idx:
             raise ValueError("Cannot provide both a placeholder and an idx")
 
@@ -371,9 +374,23 @@ def get_sql(self, **kwargs: Any) -> str:
 class ValueWrapper(Term):
     is_aggregate = None
 
-    def __init__(self, value: Any, alias: Optional[str] = None) -> None:
+    def __init__(
+        self, value: Any, alias: Optional[str] = None, allow_parametrize: bool = True
+    ) -> None:
+        """
+        A wrapper for a constant value such as a string or number.
+
+        :param value:
+            The value to be wrapped.
+        :param alias:
+            An optional alias for the value.
+        :param allow_parametrize:
+            Whether the value should be replaced with a parameter in the query if parameterizer
+            is used.
+        """
         super().__init__(alias)
         self.value = value
+        self.allow_parametrize = allow_parametrize
 
     def get_value_sql(self, **kwargs: Any) -> str:
         quote_char = kwargs.get("secondary_quote_char") or ""
@@ -409,7 +426,11 @@ def get_sql(
         parameterizer: Optional[Parameterizer] = None,
         **kwargs: Any,
     ) -> str:
-        if parameterizer is None or not parameterizer.should_parameterize(self.value):
+        if (
+            parameterizer is None
+            or not parameterizer.should_parameterize(self.value)
+            or not self.allow_parametrize
+        ):
             sql = self.get_value_sql(
                 quote_char=quote_char, secondary_quote_char=secondary_quote_char, **kwargs
             )

tests/test_terms.py

@@ -1,7 +1,7 @@
 from unittest import TestCase
 
 from pypika import Field, Query, Table
-from pypika.terms import AtTimezone
+from pypika.terms import AtTimezone, Parameterizer, ValueWrapper
 
 
 class FieldAliasTests(TestCase):
@@ -49,3 +49,15 @@ def test_passes_kwargs_to_field_get_sql(self):
             'FROM "customers" JOIN "accounts" ON "customers"."account_id"="accounts"."account_id"',
             query.get_sql(with_namespace=True),
         )
+
+
+class ValueWrapperTests(TestCase):
+    def test_allow_parametrize(self):
+        value = ValueWrapper("foo")
+        self.assertEqual("'foo'", value.get_sql())
+
+        value = ValueWrapper("foo")
+        self.assertEqual("?", value.get_sql(parameterizer=Parameterizer()))
+
+        value = ValueWrapper("foo", allow_parametrize=False)
+        self.assertEqual("'foo'", value.get_sql(parameterizer=Parameterizer()))