Question: why "synchronize from QField" updates/changes the project used to generate the off-line project with "Package for Qfield"?

[gioman]

What is the bug or the crash? What were your expectations and what actually happened?

This could be another case of me overlooking docs, if is the case forgive me.

It was a while since I used QFieldsync and can't remember if this was always the case or not.

I'm finding a little puzzling that when using "synchronize from QField" this changes/updates the project used to generate the off-line project with "Package for Qfield".

To be clear:

• take a project A with a postgis layer within the folder "source"
• put it off-line with "Package for Qfield", project is called B within the folder "offline"
• make changes to off-line data in B
• push changes to postgis with "synchronize from QField" > it works, but also A is changed/modified in a way that now the layer do not point anymore to postgis, but rather to the off-line data within "offline"

Why? If there is a reason, is there a way to avoid it?

Steps to reproduce the issue

See above.

QGIS version

3.40

QFieldSync Version

4.17.3

Operating system name

Windows

Operating system version

11

Reinstall QFieldSync

• I have a fresh install of the latest QFieldSync version on a new QGIS profile, but the problem persists.
• Problem can be reliably reproduced, doesn't happen randomly.
• Problem happens with all files and projects, not only some files or projects.

Additional context

No response

[m-kuhn]

Hi @gioman
Can you confirm which project is open when you "sync from qfield", the project A or B?

IIRC this does make a differenct, but I haven't used cable export / import recently.

[gioman]

Hi Matthias,

Can you confirm which project is open when you "sync from qfield", the project A or B?

B

[m-kuhn]

Does it change something if it's A?

[gioman]

Does it change something if it's A?

Hi Matthias, the question does not makes sense, I think.

Is project B that has new data stored as GPKG, is that data that needs to be synched back to the database. The point/question is why qfieldsync changes A even when pointing it to the folder that contains B... This is cause of problems... In the very simple scenario I described A is perfectly working project pointing to a number of postgis layers and after the sync it gets mangled for no reason.

[m-kuhn]

Hi Giovanni

As I said, it's been a while since I used cable sync last time. I agree that what you describe does sound unexpected. I'm just forwarding suggestions for things to try from the dev team.

[gioman]

I'm just forwarding suggestions for things to try from the dev team.

@m-kuhn I understand, that's why I wrote "I Think" ;)

[suricactus]

push changes to postgis with "synchronize from QField" > it works, but also A is changed/modified in a way that now the layer do not point anymore to postgis, but rather to the off-line data within "offline"

This is weird and IMO it's wrong. @SeqLaz can you confirm this behavior?

[SeqLaz]

Is the test still needed?

[gioman]

Is the test still needed?

@SeqLaz not sure on your side, but here I can easily replicate the problem.

[gdt]

I'm seeing something related. I have a project with just geopackage layers (and a georeferenced tiff but that's not problematic, and it's read only). I do not use QFieldCloud. I set up layer prefs to copy, mostly, and offline edit for a few "capture" layers. I do "package for Qfield" (down arrow icon) and get a directory (in nextcloud). on the phone in QField, I import that dir, and I digitize some points. I then export to another dir in nextcloud (QFIeld/foo-export, vs QField/foo that I imported from). Back in qgsi I "synchronize from" (up arrow icon). It seems that both:

• the foo.qgz file is written
• the project (on desktop) appears modified.

I realize syncing is hard, you need metadata, etc. I expect the offline edit data layers to get modified, by replaying the transaction log. Indeed, that's the point.

I do not expect the project file to change. If I selected a layer, or expanded/collapsed some tree view, that's just the UI on the phone. If QField had the ability to change project CRS (that's crazy; don't do it), I would still NOT expect that my desktop project be changed.

So I think there's a fundamental mismatch between how I see the world (probably wrong!) and what QFieldSync is doing. At the very least this is a documentation bug as it should be explained what if anything comes back.

I also think it's a bug if the qgis project file on desktop is written to disk as part of "sync from". If the project has to get changed, it should be changed, and appear with a * etc. But it should only be written if the user says write. And, it should not be written behind the main desktop qgis process's back -- I have seen "the file has been modified, save anyway" at some point.

Feel free to tell me to open a new bug, but I think this is all related and there's a conceptual disconnect between what at least I expect and how it works.

(I'm using qgis 3.40.11 and up-to-date QFS on NetBSD, and QF on Android 15.)

[SeqLaz]

For me, the workflow of packaging offline, then copying it to Android, making some modifications, and then importing the changes to PostgreSQL through QFieldSync did not change the data source in the original project.

The versions I used in the test were:

• QGIS 3.44.3-Solothurn
• QFieldSync v4.17.3
• QField 3.7.8
• Android 15

These were the steps I followed in the complete test. It would be good for @gioman and @gdt to see the steps to determine if there is something different in your workflows that can be considered.

@gdt Could it be possible for you to test on a newer QGIS version?

@gioman Could be possible to test the connection velocity of your PostgreSQL provider?.. Maybe the issue could be related that it take a long time making the changes in the background.

Test QField sync with PostGIS offline converted 001.pdf

[gioman]

@gioman Could be possible to test the connection velocity of your PostgreSQL provider?.. Maybe the issue could be related that it take a long time making the changes in the background.

@SeqLaz no, that is not the case. It may be the case that I'm doing something wrong/unexpected, but still the result is wrong and there should be something to avoid that to happen.

Follow here below the very simple example:

1. project A with 1 postgis layer saved in folder "test_qfieldsync"

2. project A is placed offline (project B) inside a folder called "test_qfieldsync_offline"

3. open project B and some changes are made to offline data (no need to bother do it in QField, is enough to do them in QGIS)

4. changes are synched back

5. synch is ok, but now open project A and you'll see that the layer is pointing to the GPKG in the "test_qfieldsync_folder" rather than PostGIS.

[gdt]

I was actually using 3.40.11, and am not sure when I will get to updating to the new LTR.

Just to be clear, I am not using postgis layers in QField (yet). I was making an observation that there appears to be an architectural issue with the project file being modified/written when my understanding of the intended semantics says that this should not happen.