Thanks, it worked!
I tried something similar using the @hybrid_property decorator, but could
not get it to work. What exactly is the difference between that and the
@property decorator?
Greg--
On Wed, Jun 7, 2017 at 5:08 PM, mike bayer <mike...@zzzcomputing.com> wrote:
>
>
> On 06/07/2017 02:31 PM, GMS wrote:
>
>> I am sure this is easier than I am making it, but I just want to add a
>> property to a class so that decimal representations get truncated at 3
>> decimal digits.
>>
>> My class is this:
>>
>> class Measures(Model):
>> __tablename__= 'xcelera_measures'
>> id= Column(Numeric,primary_key=True)
>> studyidk= Column(Numeric, ForeignKey('xcel.studyidk'))
>> xceleragroup= relationship("Xcelera")
>> explainstring= Column(String(255))
>> mrn= Column(String(255))
>> value= Column(Numeric)
>>
>> __mapper_args__= {
>> "order_by": [mrn]
>> }
>>
>>
>> and 'value' is the property/attribute that I want to also have a
>> truncated version available in the class.
>>
>> I tried adding this to the class value_new = column_property("%.3f" %
>> value())
>>
>> but got an error that
>>
>> value_new = column_property("%.3f" % value)
>>
>
> "%" is a Python function, that doesn't execute on the database. This
> works as a normal Python descriptor:
>
> class MyClass(Base):
> # ...
>
> @property
> def value_new(self):
> return "%.3f" % self.value
>
>
>
>
>
>
>
>
>> TypeError: float argument required, not Column
>>
>> I also tried this as a hybrid_property, but I don't think I was using it
>> correctly.
>>
>> All I want to do is have the truncated version of my attribute available
>> in my class.
>>
>> Thanks!
>>
>> Greg--
>>
>>
>> --
>> 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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>
> --
> 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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--
Greg M. Silverman
› flora-script <http://flora-script.grenzi.org/> ‹
› grenzi.org ›
--
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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