[sqlalchemy] Re: SQL Alchemy TypeDecorator
This is usually done in the ORM with functions, and possibly hybrids. See https://docs.sqlalchemy.org/en/14/orm/mapped_attributes.html On Tuesday, August 9, 2022 at 1:55:45 PM UTC-4 Justvuur wrote: > Hi there, > > Is there a way to pass/access model data for a row within the " > process_result_value" method of a TypeDecorator? > > For example, I want to decrypt the value but only if another value in the > same model row is true/false. > > Regards, > Justin > > > -- 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. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/daa3-b548-4d33-a638-a7fae644f322n%40googlegroups.com.
[sqlalchemy] Re: SQLAlchemy exists() used with first() ?
I think you misunderstand `exists()` in SQLAlchemy and SQL. `exists()` is
a convenience function to create a SQL `EXISTS` clause, which is an
operator used for filtering subqueries.
The 'from_exists' is just a subquery. It is supposed to be used within a
query which would then limit the query, not executed itself.
See
https://docs.sqlalchemy.org/en/14/core/selectable.html?#sqlalchemy.sql.expression.Exists
https://docs.sqlalchemy.org/en/14/core/selectable.html?#sqlalchemy.sql.expression.exists
https://docs.sqlalchemy.org/en/14/orm/query.html#sqlalchemy.orm.Query.exists
https://www.w3schools.com/sql/sql_exists.asp
On Tuesday, August 9, 2022 at 2:05:56 PM UTC-4 Justvuur wrote:
> Hi there,
>
> When creating another column property in a model that makes use of the
> exists(), I noticed that the exists does a "select *".
>
> *For example, the form exists below:*
> class Contact(ResourceMixin, db.Model):
> __tablename__ = 'contacts'
>
> form_contacts = db.relationship(FormContact, backref='contact',
> passive_deletes=True)
>
> form_exists = column_property(
> exists().where(and_( FormContact .form_contact_id == id,
> FormContact.partnership_id == partnership_id
> )).label('form_contact_exist'), deferred=True
> )
> *prints out to be something like:*
> exists(select * from form_contacts where form_contacts.form_contact_id ==
> id and form_contacts. partnership_id == partnership_id)
>
> Does the exists "stop" the query once one row is returned or does it
> execute the entire select all query?
> If the latter, is there a way to limit the select all to one row?
>
> Regards,
> Justin
>
--
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] SQLAlchemy exists() used with first() ?
Hi there,
When creating another column property in a model that makes use of the
exists(), I noticed that the exists does a "select *".
*For example, the form exists below:*
class Contact(ResourceMixin, db.Model):
__tablename__ = 'contacts'
form_contacts = db.relationship(FormContact, backref='contact',
passive_deletes=True)
form_exists = column_property(
exists().where(and_( FormContact .form_contact_id == id,
FormContact.partnership_id == partnership_id
)).label('form_contact_exist'), deferred=True
)
*prints out to be something like:*
exists(select * from form_contacts where form_contacts.form_contact_id ==
id and form_contacts. partnership_id == partnership_id)
Does the exists "stop" the query once one row is returned or does it
execute the entire select all query?
If the latter, is there a way to limit the select all to one row?
Regards,
Justin
--
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] SQL Alchemy TypeDecorator
Hi there, Is there a way to pass/access model data for a row within the " process_result_value" method of a TypeDecorator? For example, I want to decrypt the value but only if another value in the same model row is true/false. Regards, Justin -- 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. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/ea4cc84a-207d-4415-b995-2852ed6f2a47n%40googlegroups.com.
