[gdal-dev] cannot write to gdal_array

[Jon Morris]

Thanks for the quick fix, Even! Glad it wasn't just something I'd missed.

I'm not entirely clear on the uses for gdal_array. Are there cases where it is better than using a MEM raster? Is there any more detailed documentation?

Thanks,

Jon

-----Original Message-----
From: Even Rouault <even.rouault at spatialys.com>
Sent: 13 March 2020 15:42
To: gdal-dev at lists.osgeo.org
Cc: Jon Morris <Jon.Morris at jbarisk.com>
Subject: Re: [gdal-dev] cannot write to gdal_array

Jon,

> I'm trying to upgrade from GDAL 2.2.0 to 3.0.4 and some of our tests
> are failing. We're using gdal_array.OpenArray() to create temporary
> datasets and all the tests where we call band.WriteArray() are failing
> with the error "CPLError: Write operation not permitted on dataset
> opened in read-only mode."
>
> I can't see any way to open a gdal_array in update mode, so is this a
> change in behaviour between 2.2 and 3.0?

A not intended one. Due to gdal_array.OpenArray() having apparently always set ReadOnly setting for a unknown reason, and the MEM driver used by it underneath that didn't honour this setting until recently.

Proposed fix queued in https://github.com/OSGeo/gdal/pull/2317

> Should we be able to write to these
> datasets, or should I change the failing tests to use the MEM driver
> instead?

If you can't apply the above fix, yes, using the MEM driver is probably your best option

Even

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