[sqlalchemy] Re: Advice: Best practice for working with an existing database

[Peter Herndon]

On Friday, March 22, 2013 9:31:59 AM UTC-4, Jason wrote:



 Hi Peter,
 I think using a the declarative reflected style is a great way to 
 integrate an existing database into your application. It sounds like you 
 are doing this already, but in case you are not the reflection setup is 
 documented at 
 http://docs.sqlalchemy.org/en/rel_0_8/orm/extensions/declarative.html#using-reflection-with-declarative.
  
 It's very easy to have it populate all of your models with the correct 
 table attributes using the DeferredReflection base class. Then you just 
 have to make (almost empty) class definitions for each model. In theory you 
 could even make it so that the table name is inferred from the name of the 
 Model class, but in practice I found this to be annoying (I would 
 constantly forget how the table names compared to the class names).

 --
 Jason


Thanks, Jason! 

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[sqlalchemy] Advice: Best practice for working with an existing database

[Peter Herndon]

Hi all,

I'm new to SQLAlchemy, and looking for some advice on how to approach 
working with an existing database. The database will not be managed by 
Python, and I will need to maintain whatever library I write to keep up 
with the occasional schema change. I am looking to write a more-or-less 
definitive database access layer for myself and others to use if and when 
we write applications in Python -- the company is not primarily a Python 
shop. 

What's my best approach for building this library? Should I use 
Declarative, or should I use classical mapping -- which would be better, 
easier to maintain, easier for others to use? Should I be writing out the 
classes, or should I rely on reflection? Speaking of reflection, I've been 
using it to analyze what SQLAlchemy thinks of the schema. For a given table 
created by reflection, I'm seeing _autoincrement_column, columns, 
foreign_keys, indexes, and primary_key -- are there other table attributes 
I should be inspecting?

Thanks for your advice!

---Peter

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