Couldn't insert record with text fields with a lengh of more than 257 characters via pyodbc

Question

I have a SQL server which version is 10.50.4000. I connect to it from linux via pyodbc with SQL server Native Client 11.0 driver. Here is the table definition.

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [ctm].[services](
    [id] [char](36) NOT NULL,
    [Name] [varchar](45) NOT NULL,
    [ServiceDescription] [varchar](256) NULL,
    [Version] [varchar](45) NULL,
    [Status] [varchar](45) NOT NULL,
    [StatusDescription] [varchar](256) NULL,
    [WSDL] [text] NULL,
    [WADL] [text] NULL,
    [XSD] [text] NULL,
    [CreatedBy] [varchar](100) NULL,
    [CreatedOn] [datetime] NOT NULL,
    [CreatedAt] [varchar](45) NULL,
    [UpdatedBy] [varchar](100) NULL,
    [UpdatedOn] [datetime] NULL,
    [UpdatedAt] [varchar](45) NULL,
    [deleted] [bit] NULL
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

The field 'WSDL' is used to keep schema of a web service. I had read the schema file and stored it into a string. But when I tried to insert the record into database server, I got bellow error message:

Traceback (most recent call last): File "", line 1, in pyodbc.DataError: ('22001', '[22001] [Microsoft][SQL Server Native Client 11.0]String data, right truncation (0) (SQLExecDirectW)')

Here is the command I executed:

cursor.execute("""insert into ctm.services (id, Name, ServiceDescription, Version, Status,StatusDescription, WSDL, WADL, XSD, CreatedBy, CreatedOn, CreatedAt, UpdatedBy, UpdatedOn,UpdatedAt, deleted) values(?, ?, ?, ?, ?, ?, ?, ?, ?, ?,current_timestamp, ?, null, null, null, ?) """, 'abcdefghijklmn', 'whatservice', 'testing', '1.0.0', 'active', '', 'NOTES!!!This should be a schema file context. But it could not be shown for some reason. So I input garbage message here', 'null', 'null', getpass.getuser(), socket.gethostname(), '0')

When the string size of WSDL is less than 257 characters, I could insert the record into data base server. If it is larger than 257, it failed. But as we can see, the field type of WSDL is text. It allows 2147483647 characters. Please check below debug output:

>>> for row in cursor.columns(table='services'):
...       print row.column_name + " : " + str(row.data_type) + " size:" + str(row.column_size)
... 
id : 1 size:36
Name : 12 size:45
ServiceDescription : 12 size:256
Version : 12 size:45
Status : 12 size:45
StatusDescription : 12 size:256
WSDL : -1 size:2147483647
WADL : -1 size:2147483647
XSD : -1 size:2147483647
CreatedBy : 12 size:100
CreatedOn : 93 size:23
CreatedAt : 12 size:45
UpdatedBy : 12 size:100
UpdatedOn : 93 size:23
UpdatedAt : 12 size:45
deleted : -7 size:1
name : -9 size:128
service_id : 4 size:10
principal_id : 4 size:10
service_queue_id : 4 size:10

I had used wireshark to debug and found that the sql command was not sent to the sql server. So the error message must come from the SQL server Native Client driver.

I tried to google for a solution but couldn't find anything. Is there anyone came across with same issues before?

P.S. I had tried same command under Microsoft SQL Server Management Studio. It works without any problems. So the issue could be from the ODBC driver or the mismatching between ODBC driver and pyodbc.