Build string/int processors for JSONIndexType, JSONPathType

Fixed regression in JSON datatypes where the "literal processor" for
a JSON index value, that needs to take effect for example within DDL,
would not be invoked for the value.  The native String and Integer
datatypes are now called upon from within the JSONIndexType
and JSONPathType.  This is applied to the generic, Postgresql, and
MySQL JSON types.

Change-Id: Ifa5f2acfeee57a79d01d7fc85d265a37bd27c716
Fixes: #3765

1 files changed, 40 insertions, 2 deletions

diff --git a/lib/sqlalchemy/sql/sqltypes.py b/lib/sqlalchemy/sql/sqltypes.py
index 977231336..b55d435ad 100644
--- a/lib/sqlalchemy/sql/sqltypes.py
+++ b/lib/sqlalchemy/sql/sqltypes.py
@@ -1789,7 +1789,45 @@ class JSON(Indexable, TypeEngine):
          """
         self.none_as_null = none_as_null
 
-    class JSONIndexType(TypeEngine):
+    class JSONElementType(TypeEngine):
+        """common function for index / path elements in a JSON expression."""
+
+        _integer = Integer()
+        _string = String()
+
+        def string_bind_processor(self, dialect):
+            return self._string._cached_bind_processor(dialect)
+
+        def string_literal_processor(self, dialect):
+            return self._string._cached_literal_processor(dialect)
+
+        def bind_processor(self, dialect):
+            int_processor = self._integer._cached_bind_processor(dialect)
+            string_processor = self.string_bind_processor(dialect)
+
+            def process(value):
+                if int_processor and isinstance(value, int):
+                    value = int_processor(value)
+                elif string_processor and isinstance(value, util.string_types):
+                    value = string_processor(value)
+                return value
+
+            return process
+
+        def literal_processor(self, dialect):
+            int_processor = self._integer._cached_literal_processor(dialect)
+            string_processor = self.string_literal_processor(dialect)
+
+            def process(value):
+                if int_processor and isinstance(value, int):
+                    value = int_processor(value)
+                elif string_processor and isinstance(value, util.string_types):
+                    value = string_processor(value)
+                return value
+
+            return process
+
+    class JSONIndexType(JSONElementType):
         """Placeholder for the datatype of a JSON index value.
 
         This allows execution-time processing of JSON index values
@@ -1797,7 +1835,7 @@ class JSON(Indexable, TypeEngine):
 
         """
 
-    class JSONPathType(TypeEngine):
+    class JSONPathType(JSONElementType):
         """Placeholder type for JSON path operations.
 
         This allows execution-time processing of a path-based