Insert data into Spanner with parameters

Question

I want to pass variables to my SQL insert statement. Spanner seems to use the following syntax to specify a variable @param. As described in https://cloud.google.com/spanner/docs/lexical#query-parameters. I am new to Python so I don't think I am quite understand the syntax because it throws the error "No parameter found for binding: messageid" The same code executes correctly with hard coded values.

Here is my code:

messageid = str(uuid.uuid4())
sender = newmsg['Sender']
recipient = newmsg['Recipient']
message = newmsg['Message']

def insert_message(transaction):
    self.logger.debug("Inside insert_with_dml")
    row_ct = transaction.execute_update(
        "INSERT MESSAGE_STORE (MessageId, Message, MessageRecipient, MessageSender) "
        " VALUES (@messageid, @message, @recipient, @sender)"
    )

Update: Here is the working code if anyone is interested

def insertmessage(self, newmsg):
            messageid = str(uuid.uuid4())
            sender = newmsg['Sender']
            recipient = newmsg['Recipient']
            message = newmsg['Message']

            data_type = param_types.Struct([
                    param_types.StructField('Id', param_types.STRING),
                    param_types.StructField('Msg', param_types.STRING),
                    param_types.StructField('Requestor', param_types.STRING),
                    param_types.StructField('MsgRecipient', param_types.STRING)
            ])

            data_values = (messageid, message, recipient, sender)

            def insert_message(transaction):
                self.logger.debug("Inside insert_with_dml")
                row_ct = transaction.execute_update(
                    "INSERT MESSAGE_STORE (MessageId, Message, MessageRecipient, MessageSender) "
                        "VALUES (@values.Id, @values.Msg, @values.Requestor, @values.MsgRecipient)",
                        params={'values' : data_values},
                        param_types={'values' : data_type}
            )

                self.logger.debug("{} record(s) inserted.".format(row_ct))

            try:
                self.client.run_in_transaction(insert_message)
            except Exception as e:
                self.logger.debug(e)

            self.logger.debug("Before Output")
            output = "{ 'Message Id':" +  messageid +", 'Result Code': '1' }"
            return output

Answer 1

See the following documentation section on Using STRUCT objects as bound parameters in SQL queries