[Qgis-developer] Memory Layers - some proposals

[Mathieu Pellerin]

Thoughts:
- I don't think warning should be occurring when creating a memory layer
(that is when pasting as new layer, when adding the result of a processing
algorithm as memory layer, or creating a blank memory layer)
- I don't think the user should be able to disable the warning message
(which imo should be a dialog with saving shortcuts), the resulting data
loss is too critical; it's like opening a project with missing layers, qgis
doesn't (and shouldn't) allow for this dialog to be skipped
- IMO best to have: a/ a message bar when saving project while in an
ongoing session, and a missing layer-like warning dialog when closing
project
On 25 Sep 2014 12:15, "Denis Rouzaud" <denis.rouzaud at gmail.com> wrote:

>
> On 25.09.2014 04:02, Mathieu Pellerin wrote:
>
>    Regarding the saving aspect of it, IMO it needs to be worked out. I've
> had a couple of users over here already reporting "data loss" with the
> following scenario:
>  1. Open his/her project
> 2. Copies one polygon from a large dataset and pastes is as a new memory
> layer (very useful feature introduced in QGIS 2.x)
>  3. Styles the memory layer, and saves the project
>  4. The next day, when he/she re-opens the project, the polygon is gone
>
>  Throughout the above mentioned workflow, there was never _any_ indication
> that the pasted memory layer would not be saved when saving the project.
>
>  If QGIS further ease access to memory layers via incorporating the new
> memory layer function into the core (which I hope its done :) ), and decide
> against saving across project session, then there must be a UX to deal with
> that, instead of silently killing the data of the memory layer(s). One way
> forward would be to have a warning upon closing a project that has
> non-saveable memory layers to warn the users. That warning should offer for
> users to save the memory layers onto a proper format (possibly like the
> missing layer dialog, with a list of all the memory layers and an input to
> add the saved file location/name).
>
> I would be in favor of a warning when first create a memory layer. The
> warning would say you can't save them except from using a plugin. And,
> there would be a checkbox "do not display this warning anymore".
>
>
>
>
>  Math
>
> On Thu, Sep 25, 2014 at 4:07 AM, Martin Dobias <wonder.sk at gmail.com>
> wrote:
>
>> Hi Nyall
>>
>> On Thu, Sep 25, 2014 at 3:31 AM, Nyall Dawson <nyall.dawson at gmail.com>
>> wrote:
>> > Hi all,
>> >
>> > The recent discussion around memory layers in another thread has
>> started me
>> > thinking about the best way to expose them more readily to users.
>> >
>> > As such, I've opened a pull request which ports Borys Jurgiel's "New
>> Memory
>> > Layer" plugin to core (PR #1591). Hopefully this can be merged for 2.6.
>> It's
>> > more or less a direct port - I've left it without the ability to specify
>> > fields at creation time as I believe that field creation would indicate
>> that
>> > we are encouraging users to store real data in these layers, which is
>> > something we should avoid.
>>
>> Cool - from time to time it is handy to make a memory layer for some
>> temporary data and having to use a plugin / python console for the
>> creation is suboptimal...
>>
>> > What I'm thinking though is that we should rename "memory layers"
>> within the
>> > UI. The name suggests that they are remembered, and conveys more of a
>> > permanent feel.
>> >
>> > I think that for 2.6 we could rename them to "temporary scratch
>> layers", and
>> > then for >2.6 (after we port the memory layer saving plugin/decide on a
>> > suitable format for saving them) drop the " temporary" part of this
>> name. So
>> > they'll be just "scratch layers".
>>
>> I like the name "scratch layer" - and I wouldn't mind having it from
>> 2.6 even without the "temporary" part although there is no saving for
>> it. (Saving is still a bit controversial for me as we would
>> inadvertently create another vector file format - unless we would ask
>> user to save the layer data into one of OGR supported formats or
>> spatialite DB.)
>>
>> Cheers
>> Martin
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>
>
>
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