Hi Mike,
Thanks, `literal` is good.
Regarding the `insert_where` function, would you mind providing some
feedback on the API? I'm writing a library that uses SQLAlchemy so I would
like this API to be relatively consistent with the SQLAlchemy approach.
So far I have been doing it like the following:
def insert_where(table, where, **kwargs):
....
insert_where(
Project,
name=project_name, user_id=user_id,
where=exists(
...
)
Another option might be:
def insert_where(table, where, *args, **kwargs):
...
Where *args could be a dictionary, or tuple, or list of dict/tuple, similar
to the insert(Project).values API.
Any thoughts?
Best regards,
Matthew
On Wednesday, March 23, 2022 at 6:21:34 AM UTC-7 Mike Bayer wrote:
>
>
> On Tue, Mar 22, 2022, at 2:46 PM, mkmo...@gmail.com wrote:
>
> I would like to do a conditional insert of a a single row. This is often
> useful in a CRUD app for checking permissions and inserting in a single
> database call:
>
> INSERT INTO project (name, user_id)
> SELECT :name, :user_id
> WHERE EXISTS (
> SELECT 1
> FROM users
> WHERE id = :user_id
> and role = :admin_role
> )
>
> In SQLAlchemy I use the following which isn't the most beautiful:
>
> ins = insert(Project).from_select(
> ['name', 'user_id'],
>
> select(
> bindparam('name', project_name),
> bindparam('user_id', user_id),
> ).where(
> exists(
> select(1).select_from(
> User
> ).where(
> User.c.id == 1,
> User.c.role == "ADMIN",
> )
> )
> )
> )
>
> I find my use of `bindparam` in the select statement to be rather noisy.
>
> Does anyone know of a way to make it a bit more easier on the eyes?
>
>
> you don't need to name those parameters, you can use sqlalchemy.literal():
>
> select(literal(project_name), literal(user_id)).where( ... )
>
>
>
>
> Would you be open to making a SQLAlchemy conditional insert API?
>
> Project.insert(name=project_name, user_id=user_id).where(
> exists(
> # ...
> )
> )
>
> In other words, create a method "where" on Insert that will not use VALUES
> and instead use a SELECT.
>
>
> this is what you should do in your own application. Make a function
> called insert_where() and pass along the arguments, then you won't have to
> see that code everywhere, if this is a common idiom you like to use.
>
>
>
>
>
> Thanks and best regards,
>
> Matthew
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
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