Re: In-memory queryset

2017-03-08 Thread Neal Todd 
Hi Paul,

Depending on your use cases django-modelcluster might be of some use:

https://github.com/wagtail/django-modelcluster

It's primarly for dealing with a bunch of models that have foreign key 
relationships, but before they're written to a database (i.e before they 
have primary keys that allow the foreign keys to work). At some point they 
are typically committed to a database but they also could be ephemeral or 
serialised and handed off to something else.

It only supports a subset of the QuerySet API (pragmatically that which 
allows it to serve the purpose it was created for).

Cheers, Neal   

On Tuesday, March 7, 2017 at 2:57:57 PM UTC, pa...@dabapps.com wrote:
>
>
> It would be really convenient for me if there was an implementation of the 
> QuerySet API which instead of using a database as its data source, used 
> in-memory model instance that had not been persisted to the database at all.
>
> I looked around and found nothing like this.
>
> Is this because nothing like this exists? Is it because it's a terrible 
> idea for a reason that's not obvious to me? Would it not be awesome for the 
> API for interacting with collections of in-memory instances and with a 
> database-backed collection to be the same?
>
>

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Re: In-memory queryset

2017-03-07 Thread Tim Chase 
On 2017-03-07 07:17, Jacob Kaplan-Moss wrote:
> It's certainly _possible_ to implement a in-memory datastore, and
> it might be pretty useful. It's just pretty dang hard to do more
> than the first 20% or so.

Would there also be issues with WSGI spinning up/down various Django
processes?  Any in-memory (in-process) data would be lost when the
process goes down.  I could see it working for an individual dev
server or if you could guarantee that a single WSGI process remains
running indefinitely. But for those, I'd just go with sqlite's
":memory:" option.

-tkc



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Re: In-memory queryset

2017-03-07 Thread Jacob Kaplan-Moss 
Hey Paul -

There are a couple of implementations I'm aware of:

https://github.com/stphivos/django-mock-queries
https://github.com/dcramer/mock-django

Neither are a complete implementation of the QuerySet API, and I think this
is because the QuerySet API surface is _huge_. Implementing the entire API
would be a monumental task (especially if you start wanting to implement
some of the more complex operations, like annotate/aggregate). At a certain
point, it because easier to just use a real database -- most people use
SQLite at that point.

It's certainly _possible_ to implement a in-memory datastore, and it might
be pretty useful. It's just pretty dang hard to do more than the first 20%
or so.

Jacob

On Tue, Mar 7, 2017 at 6:13 AM,  wrote:

> Hi,
>
> It would be really convenient for me if there was an implementation of the
> QuerySet API which instead of using a database as its data source, used
> in-memory model instance that had not been persisted to the database at all.
>
> I looked around and found nothing like this.
>
> Is this because nothing like this exists? Is it because it's a terrible
> idea for a reason that's not obvious to me? Would it not be awesome for the
> API for interacting with collections of in-memory instances and with a
> database-backed collection to be the same?
>
> Many thanks,
>
> Paul
>
> --
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> msgid/django-developers/d4f7c142-5d3f-4158-98bb-
> 1e2171f0e63e%40googlegroups.com
> 
> .
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Re: In-memory queryset

2017-03-07 Thread ludovic coues 
This look like a question for django user.

The QuerySet API is only an abstraction layer to SQL code. That's why
it require a database.
If you really don't want to store your object on a filesystem, sqlite
support database living only in memory. That's mainly for testing
purpose but that could fit your use-case. And django support multiple
database.

2017-03-07 15:13 GMT+01:00  :
> Hi,
>
> It would be really convenient for me if there was an implementation of the
> QuerySet API which instead of using a database as its data source, used
> in-memory model instance that had not been persisted to the database at all.
>
> I looked around and found nothing like this.
>
> Is this because nothing like this exists? Is it because it's a terrible idea
> for a reason that's not obvious to me? Would it not be awesome for the API
> for interacting with collections of in-memory instances and with a
> database-backed collection to be the same?
>
> Many thanks,
>
> Paul
>
> --
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-- 

Cordialement, Coues Ludovic
+336 148 743 42

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In-memory queryset

2017-03-07 Thread paul 
Hi,

It would be really convenient for me if there was an implementation of the 
QuerySet API which instead of using a database as its data source, used 
in-memory model instance that had not been persisted to the database at all.

I looked around and found nothing like this.

Is this because nothing like this exists? Is it because it's a terrible 
idea for a reason that's not obvious to me? Would it not be awesome for the 
API for interacting with collections of in-memory instances and with a 
database-backed collection to be the same?

Many thanks,

Paul

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