So far I tried to call my function by passing airport_sys_id,
project_sys_id and column name, leaving value parameter empty as it is
assigned to None by default.
I see in my logs that it tries to pass in sql query value=None, but it
doesn't work for numeric type field. It works fine for string type, but for
numeric one I receive as above: "Implicit conversion from datatype
'VARCHAR' to 'NUMERIC' is not allowed. Use the CONVERT function to run
this query.", so it seems that it treats passed None as string value.
W dniu poniedziałek, 15 lipca 2019 14:24:40 UTC+2 użytkownik Simon King
napisał:
>
> Passing None is the right way to set a column to NULL, so it sounds like
> you are doing something else wrong. How are you calling your
> update_airport_reference_temperature function?
>
> Also, enabling debug level logging (by passing echo='debug' when you
> create your SQLAlchemy engine) will show exactly what values you are
> passing to the database.
>
> Simon
>
> On Mon, Jul 15, 2019 at 10:45 AM Mirek Morek <teste...@gmail.com
> <javascript:>> wrote:
>
>> Hello Simon,
>> One extra question:
>>
>> Do you know maybe how to assign NULL field value to numeric type field
>> using sqlalchemy? I change field to some numeric value and then I want to
>> clear this field.
>>
>> I tried assign None as default for value parameter:
>>
>> [image: apt2.jpg]
>>
>>
>> But I receive:
>>
>> "Implicit conversion from datatype 'VARCHAR' to 'NUMERIC' is not
>> allowed. Use the CONVERT function to run this query."
>>
>> W dniu piątek, 12 lipca 2019 11:53:58 UTC+2 użytkownik Simon King napisał:
>>>
>>> If SQLAlchemy didn't support the second calling style, you would still
>>> be able to make this work using the Python "**" operator:
>>>
>>> updatevalues = {custom_column: value}
>>> query = AIRPORT.update().values(**updatevalues)
>>>
>>> When calling a function, passing "**somedictionary" is equivalent to
>>> passing each of the dictionary elements as keyword arguments to the
>>> function.
>>>
>>> >>> def f(a, b, c):
>>> ... print("a =", a)
>>> ... print("b =", b)
>>> ... print("c =", c)
>>> ...
>>> >>> f(a=1, b=2, c=3)
>>> a = 1
>>> b = 2
>>> c = 3
>>> >>> args = {'a': 1, 'b': 2, 'c': 3}
>>> >>> f(**args)
>>> a = 1
>>> b = 2
>>> c = 3
>>>
>>> Simon
>>>
>>> On Fri, Jul 12, 2019 at 10:28 AM Mirek Morek <teste...@gmail.com>
>>> wrote:
>>> >
>>> > It works!
>>> >
>>> > Thank you very much Simon, I really appreciate that. You saved me a
>>> lot of nerves. I would buy you a beer if I could.
>>> >
>>> > So, in general we can say that only second calling style works in my
>>> example.
>>> >
>>> > Regards.
>>> >
>>> > W dniu czwartek, 11 lipca 2019 16:35:25 UTC+2 użytkownik Simon King
>>> napisał:
>>> >>
>>> >> Here are the docs for the Update.values() method:
>>> >>
>>> >>
>>> https://docs.sqlalchemy.org/en/13/core/dml.html#sqlalchemy.sql.expression.Update.values
>>>
>>> >>
>>> >> Note that it supports two main calling styles, either keyword
>>> arguments:
>>> >>
>>> >> .values(name_column='cat')
>>> >>
>>> >> ...or passing a dictionary:
>>> >>
>>> >> .values({'name_column': 'cat'})
>>> >>
>>> >> Since you want to choose the column dynamically, you can use the
>>> >> dictionary style:
>>> >>
>>> >> updatevalues = {custom_column: value}
>>> >> query = AIRPORT.update().values(updatevalues)
>>> >>
>>> >> Hope that helps,
>>> >>
>>> >> Simon
>>> >>
>>> >> On Thu, Jul 11, 2019 at 3:00 PM Mirek Morek <teste...@gmail.com>
>>> wrote:
>>> >> >
>>> >> > Hello everyone,
>>> >> > I have a following question:
>>> >> >
>>> >> > I use sqlalchemy within my python method as follows:
>>> >> >
>>> >> >
>>> >> > I want to be able to replace 'custom_column' with parameter passed
>>> in the method. The same way as it works fine for airport_sys_id,
>>> project_sys_id and value.
>>> >> >
>>> >> > For example I want to pass in my method (1, 2, name_column, cat)
>>> and receive as follows:
>>> >> >
>>> >> > query = AIRPORT.update(). \
>>> >> > where(AIRPORT.c.airport_sys_id == 1). \
>>> >> > where(AIRPORT.c.project_sys_id == 2). \
>>> >> > values(name_column=cat)
>>> >> >
>>> >> > I searched all I could but with no success. I would be extremely
>>> thankful for your support. Regards.
>>> >> >
>>> >> >
>>> >> > --
>>> >> > SQLAlchemy -
>>> >> > The Python SQL Toolkit and Object Relational Mapper
>>> >> >
>>> >> > http://www.sqlalchemy.org/
>>> >> >
>>> >> > To post example code, please provide an MCVE: Minimal, Complete,
>>> and Verifiable Example. See http://stackoverflow.com/help/mcve for a
>>> full description.
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>>>
>>> >> > For more options, visit https://groups.google.com/d/optout.
>>> >
>>> > --
>>> > SQLAlchemy -
>>> > The Python SQL Toolkit and Object Relational Mapper
>>> >
>>> > http://www.sqlalchemy.org/
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>> --
>> SQLAlchemy -
>> The Python SQL Toolkit and Object Relational Mapper
>>
>> http://www.sqlalchemy.org/
>>
>> To post example code, please provide an MCVE: Minimal, Complete, and
>> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
>> description.
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>
--
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The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
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