Print an sqlalchemy row

Question

All I'd like to do is print a single row of an sqlalchemy table row.

Say I have:

from sqlalchemy import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

class ATable(Base):
     __tablename__ = 'atable'  
     id = Column(Integer, primary_key=True) 
     name = Column(String(255), nullable=False)

Then I'd like to output anything that looks like this:

id: 1
name: theRowName

Preferable without having to hard code in the table columns, i.e. more generally.

I've tried:

 atable = Atable()
 ... #add some values etc.
 print atable
 print str(atable)
 print repr(atable)
 print atable.__table__.c

As well as thought about implementing __str__ and __repr__, but they again lack the generality request.

There are many questions on covering a table row into JSON, but that's not really what I want, I care more about the visual output - it doesn't need to be machine readable afterwards.

Add __str__ and __repr__ methods respectively to your model, if you wish to alter the representations. — Ilja Everilä
– Ilja Everilä, Commented Jun 28, 2016 at 9:42

bimsapi · Accepted Answer · 2016-06-28 13:57:32Z

2

To be clear - you want a general method to print "col: value" without hardcoding the column names? I do not use SQLAlchemy much, but a __str__ method like this should work:

def __str__(self):
    output = ''
    for c in self.__table__.columns:
        output += '{}: {}\n'.format(c.name, getattr(self, c.name))
    return output

You can then put that method in a mixin class to use elsewhere in your models.

answered Jun 28, 2016 at 13:57

bimsapi

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1 Comment

DBCerigo Over a year ago

Nice, thanks! I ended up making a custom 'printer' which does something similar, though not as elegantly as yours so I will be using your code in my 'printer'. I think I should have been clearer that I had already had a lot of different and changing models and really only one very specific place I wanted to print the rows. So it was less effort having it specific on the outside of the class than change all my models' classes. Thanks again.

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