Add support for binding parameters by index

Signed-off-by: Salil Chandra <[email protected]>

comdb2/_ccdb2.pyx

@@ -402,14 +402,21 @@ cdef class Handle(object):
         try:
             if parameters is not None:
                 for key, val in parameters.items():
-                    ckey = _string_as_bytes(key)
+                    bind_by_index = isinstance(key, int)
+                    ckey = _string_as_bytes(key) if not bind_by_index else key
                     cval = _ParameterValue(val, key)
                     param_guards.append(ckey)
                     param_guards.append(cval)
                     if cval.list_size == -1:
-                        rc = lib.cdb2_bind_param(self.hndl, <char*>ckey,
-                                                cval.type, cval.data, cval.size)
+                        if bind_by_index:
+                            rc = lib.cdb2_bind_index(self.hndl, ckey,
+                                                    cval.type, cval.data, cval.size)
+                        else:
+                            rc = lib.cdb2_bind_param(self.hndl, <char*>ckey,
+                                                    cval.type, cval.data, cval.size)
                     else:
+                        if bind_by_index:
+                            raise ValueError("Cannot bind an array by index")
                         # Bind Array if cval is an array
                         rc = lib.cdb2_bind_array(self.hndl, <char*>ckey, cval.type, cval.data, cval.list_size, cval.size)
                     _errchk(rc, self.hndl)

comdb2/_cdb2api.pxd

@@ -76,6 +76,7 @@ cdef extern from "cdb2api.h" nogil:
     void* cdb2_column_value(cdb2_hndl_tp* hndl, int col) except +
     const char* cdb2_errstr(cdb2_hndl_tp* hndl) except +
     int cdb2_bind_param(cdb2_hndl_tp *hndl, const char *name, int type, const void *varaddr, int length) except +
+    int cdb2_bind_index(cdb2_hndl_tp *hndl, int index, int type, const void *varaddr, int length) except +
     int cdb2_bind_array(cdb2_hndl_tp *hndl, const char *name, cdb2_coltype, const void *varaddr, size_t count, size_t typelen) except +
     int cdb2_clearbindings(cdb2_hndl_tp *hndl) except +
     int cdb2_clear_ack(cdb2_hndl_tp *hndl) except +

comdb2/cdb2.py

@@ -99,6 +99,13 @@
 examples we make use of the `list` constructor to turn the iterable returned
 by `Handle.execute` into a list of result rows.
 
+You can also bind by index (starting from 1) instead of by name with placeholders specified using ``?``
+in sequence. Note that binding an array by index is not supported. For example:
+
+    >>> query = "select 25 between ? and ?"
+    >>> print(list(hndl.execute(query, {1: 20, 2: 42})))
+    [[1]]
+
 Types
 -----
 
@@ -148,6 +155,7 @@
     "ColumnType",
     "ConnectionFlags",
     "Value",
+    "IndexParameterValue",
     "ParameterValue",
 ]
 
@@ -160,14 +168,17 @@
     datetime.datetime,
     DatetimeUs,
 ]
-ParameterValue = Union[
+IndexParameterValue = Union[
     None,
     int,
     float,
     bytes,
     str,
     datetime.datetime,
     DatetimeUs,
+]
+ParameterValue = Union[
+    IndexParameterValue,
     List[int],
     List[float],
     List[bytes],
@@ -359,7 +370,7 @@ def row_factory(
     def execute(
         self,
         sql: str | bytes,
-        parameters: Mapping[str, ParameterValue] | None = None,
+        parameters: Mapping[str, ParameterValue] | Mapping[int, IndexParameterValue] | None = None,
         *,
         column_types: Sequence[ColumnType] | None = None,
     ) -> Handle:
@@ -383,6 +394,7 @@ def execute(
             sql (str): The SQL string to execute.
             parameters (Mapping[str, Any]): An optional mapping from parameter
                 names to the values to be bound for them.
+                (Mapping[int, Any]): Can also map from parameter index starting with 1 (if not array)
             column_types (Sequence[int]): An optional sequence of types (values
                 of the `ColumnType` enumeration) which the columns of the
                 result set will be coerced to.
@@ -403,6 +415,12 @@ def execute(
             ...     print(row)
             [1, 2]
             [2, 4]
+
+            >>> for row in hndl.execute("select 1, 2 UNION ALL select ?, ?",
+            ...                         {1: 2, 2: 4}):
+            ...     print(row)
+            [1, 2]
+            [2, 4]
         """
         if parameters is None:
             parameters = {}

tests/test_cdb2.py

@@ -62,8 +62,12 @@ def test_binding_parameters():
     hndl.execute("insert into simple(key, val) values(@k, @v)", dict(k=3, v=4))
     assert hndl.get_effects()[0] == 1
 
+    hndl.execute("insert into simple(key, val) values(?, ?)", {1: 5, 2: 6})
+    hndl.execute("insert into simple(key, val) values(?, ?)", {2: 8, 1: 7})
+    assert hndl.get_effects()[0] == 1
+
     rows = list(hndl.execute("select key, val from simple order by key"))
-    assert rows == [[1, 2], [3, 4]]
+    assert rows == [[1, 2], [3, 4], [5, 6], [7, 8]]
 
 
 def test_commit_failures():
@@ -304,6 +308,17 @@ def test_parameter_name_in_binding_errors_noexception():
     )
 
 
+def test_binding_array_by_index():
+    hndl = cdb2.Handle("mattdb", "dev")
+
+    with pytest.raises(Exception) as exc:
+        hndl.execute("select * from carray(?)", {1: [1, 2, 3]})
+
+    assert exc.value.args[0] == (
+        "Cannot bind an array by index"
+    )
+
+
 def test_specifying_column_types():
     # GIVEN
     hndl = cdb2.Handle("mattdb", "dev")