On PUT-Request respond with updated resource-data - commit(), transaction manager

[benko...@gmail.com]

Hello!

I'm working on a project where I use Pyramid together with Cornice to provide a REST-API. When I do a PUT-request, I would like to return the updated resource in the Response. But as the COMMIT only happens after returning the Response and request.dbession.commit() is not allowed in the default configuration (SQLAlchemy-scaffold - "Transaction must be committed using the transaction manager"), I'm wondering how I could return the resource with the latest DB-State after updating it with the PUT-payload.

Using a GET right after a successful PUT is my current solutions, but that feels like an unclean workaround.

Is there a way to do this without replacing the whole transaction-mechanism, which seems complex?

Kind regards,

Christian

[Mikko Ohtamaa]

Hi Christian,

I'm working on a project where I use Pyramid together with Cornice to provide a REST-API. When I do a PUT-request, I would like to return the updated resource in the Response. But as the COMMIT only happens after returning the Response and request.dbession.commit() is not allowed in the default configuration (SQLAlchemy-scaffold - "Transaction must be committed using the transaction manager"), I'm wondering how I could return the resource with the latest DB-State after updating it with the PUT-payload.

Using a GET right after a successful PUT is my current solutions, but that feels like an unclean workaround.

Is there a way to do this without replacing the whole transaction-mechanism, which seems complex?

If I read this correctly this is not complex at all.

Run:

request.dbsession.flush()

And SQLAlchemy will sync all in-memory objects from the database.

http://docs.sqlalchemy.org/en/latest/orm/session_api.html?highlight=flush#sqlalchemy.orm.session.Session.flush

 

Kind regards,

Christian

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Mikko Ohtamaa
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[benko...@gmail.com]

On Monday, 3 April 2017 21:54:28 UTC+2, Mikko Ohtamaa wrote:

Hi Christian,

I'm working on a project where I use Pyramid together with Cornice to provide a REST-API. When I do a PUT-request, I would like to return the updated resource in the Response. But as the COMMIT only happens after returning the Response and request.dbession.commit() is not allowed in the default configuration (SQLAlchemy-scaffold - "Transaction must be committed using the transaction manager"), I'm wondering how I could return the resource with the latest DB-State after updating it with the PUT-payload.

Using a GET right after a successful PUT is my current solutions, but that feels like an unclean workaround.

Is there a way to do this without replacing the whole transaction-mechanism, which seems complex?

If I read this correctly this is not complex at all.

Run:

request.dbsession.flush()

And SQLAlchemy will sync all in-memory objects from the database.

While I already had flush() in place wherever necessary, your answer made me take a closer look at my model. I realized that I'm creating my JSON-Response from persisted, therefore outdated objects, not the newly created ones - that's why I didn't see my updates. Thanks for pointing me in the right direction!