[sqlalchemy] A review of querying/searching and mutability tracking on Postgres SQL JSON and JSONB field implementations using SQLAlchemy and Sqlalchemy-Json

[Victor Reichert]

Hi,

I've been trying to better understand the properties of different Postgres 
JSON field implementations.  I wrote s script with my tests and I thought I 
would share it.  It can be found at:

https://gist.github.com/vfr292/41530bfb56778ffc26fe53c605f40feb

FWIW, I found implementing the field 
as Column(sqlalchemy_json_NestedMutable.as_mutable(pg_JSONB)) had the 
mutation tracking and querying I was looking for.

I hope this is of use to someone :)

~Victor

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Re: [sqlalchemy] get max value from multiple columns sqlalchemy

[arjun k]

Thank you Mike Bayer for your help..


On Wednesday, June 27, 2018 at 8:32:18 PM UTC+5:30, Mike Bayer wrote:
>
> On Wed, Jun 27, 2018 at 3:22 AM, arjun k > 
> wrote: 
> > Hi 
> > i was trying to convert the below query to sqlalchemy 
> > 
> > 
> > SELECT 
> >addr_idn, 
> >(SELECT MAX(LastUpdateDate) 
> >   FROM (VALUES (crt_dt),(upd_dt),) AS UpdateDate(LastUpdateDate)) 
> >AS LastUpdateDate 
> > FROM ( 
> > select a. addr_idn,a.crt_dt crt_dt , b.upd_dt upd_dt 
> > from emp_addr 
> > where emp_addr.addr_idn = 1 
> > ) a 
> > 
> > 
> > 
> > but i am not able to convert this into sqlalchemy. please help me out to 
> > convert this query. 
>
>
> the hard part here is the "FROM VALUES" which is not built-in to 
> SQLAlchemy.  There is a recipe at 
> https://bitbucket.org/zzzeek/sqlalchemy/wiki/UsageRecipes/PGValues 
> that will show how to build a "values()" function that will give you 
> the VALUES() expression you're looking for. 
>
> > 
> > -- 
> > SQLAlchemy - 
> > The Python SQL Toolkit and Object Relational Mapper 
> > 
> > http://www.sqlalchemy.org/ 
> > 
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