paramTypes property
It is not always possible for Cloud Spanner to infer the right SQL type from a JSON value.
For example, values of type BYTES and values of type STRING both
appear in params as JSON strings. In these cases, param_types can be
used to specify the exact SQL type for some or all of the SQL statement
parameters. See the definition of Type for more information about SQL
types.
Implementation
core.Map<core.String, Type>? paramTypes;