UWP. Is changing .appxmanifest triggers local app data to be removed? - windows

I want to update my application declarations (add some new) in .appxmanifest file. Also, my application has sensible data in LocalState folder, so it cannot be lost.
The question is if I add these declarations (change .appxmanifest file) will it trigger the application reinstall and as a result data loss in LocalState folder?
I found in documentation and Q&A that changes to AppManifest can trigger app reinstall but there are no details which changes exactly will bring me to this situation.

If you change this file locally and then rebuild the project the app will be reinstalled when debugging.
Changes like these won't cause a reinstall when updates are distributed through the store.

Related

How to change install location of msix bundle?

I have a WPF app that I am planning on deploying with the Windows Application Packaging Project in Visual Studio that makes the MSIX bundle for installations and future updates. The installer automatically installs the app in C:\Program Files\WindowsApps. This is fine until the program needs to cache some data or it needs to modify the appsettings file since the app does not have permission to get to these resources.
Is there a setting I can change in the packaging properties/manifest so it can install somewhere else so I can avoid these problems?
Indeed, only the Windows can write in %ProgramFiles%\WindowsApps when installing the msix package (by design). If your app is writing log files or other data inside the installation folder it will crash.
You need to either update your code to write to %AppData% or, if you don’t have access to the code, use the Package Support Framework to fix it. You can read more about here:
Package Support Framework (aka PSF)
The PSF brings support for API redirection and hooking. Thus, you can fix an app that failed to write a file in the installation folder (this is no longer allowed) and redirects it to a recommended location, or maybe simply update the app’s working directory.
As mentioned above, you cannot write in the install location of an MSIX package - this is by design.
For apps that are no longer under active developer indeed using the Packafe Support Framework is the only way to fix them. However, from what I see you are preparing to launch the app, so you have access to its code.
In this scenario, it is recommended you save all your app settings in the AppData\Roaming folder. For apps deployed as MSIX Windows will automatically redirect it under the Packages folder, but that is handled automatically by the OS, so you don't need to worry about it. More details below.
How to save data under AppData\Roaming instead of AppData\Local\Packages

Xamarin Android change Manifest to allowBackup=true at runtime

In my Xamarin Android app I have set the following in the Manifest:
<application android:allowBackup="false" />
I had to do this cause everytime I was installing the app, it kept track of the previous image of the sqlite database when some information was stored. A
fter adding that line to the Manifest, everytime I reinstall the app I have a clean database to work with, so no previous info is getting used.
But this creates another issue. I have a button on my app that simply creates a copy of the local database to the external storage.
This copy works fine if I don't set up the allowBackup="false" in the Manifest, but since I have to (for the problem I mentioned earlier), I find myself in the
impossibility to have both things working (i.e. the clean DB after each installation and the possibility to create copies of the DB to external drive).
I think that a possible workaround could be to keep the allowBackup="false" in the Manifest but change it to "true" just before creating a copy of the database.
I can then change the flag back to "false".
But how can I achieve this? I haven't found anything online on this. Thank you.
The purpose of the manifest is that it can't be changed. For example this is where you declare on what your app will have access to (until Android Marshmallow this was the only way to make such a declaration). Obviously such things cannot change at the runtime.
Also the purpose of the backup is to restore in all cases including the one that you don't like (for whatever reason which is still not clear as I don't see why your app cannot continue to work with the data it had worked properly before the app was uninstalled), so basically you don't want the backup and you should set it to false.

VS2015 Setup Project not updating Access Database included in package when reinstalling

I'm trying to build a Visual Studio Installer Setup Project that deploys multiple C# projects and some other files. Included in these other files, there are Access Database with forms that needs updates.
To illustrate the problem, I simplified it :
1- Create a new Access Database file, add a simple form to it with a button and a label and save it.
2- Add the file to the setup project;
3- Set DetectNewerInstalledVersion and RemovePreviousVersion to true
4- Build the project.
5- Run the setup executable.
To that point, everything has worked fine
6- Reopen the Access Database file, add a button or a label to the form, save it.
7- Change the Version number of the Setup project, and at the same time the ProductCode as suggested by VS2015.
8- Rebuild the setup project.
9- Reinstall the software.
Expected: the Access data should have been updated with the new button/label.
What is happening: The file hasn't been updated.
Why is that ? I've seen people talking about the Assembly version number of projects included in a setup project, but that's not my case since I'm not deploying the ouput of a project. I'm simply deploying a file that should have been removed during the uninstall process.
If I do the exact same steps as described before but with a text file in which I add text, it works fine, but for some reason in does not work with an Access Database.
What's wrong ?
If you install a data file, and then run a program that updates it you've added user data to that file, or database. The file overwrite rules don't allow a modified data file to be replaced in the kind of update that VS setups do:
https://msdn.microsoft.com/en-us/library/windows/desktop/aa370531(v=vs.85).aspx
Basically it would be a bad idea to ship a product that installs a database that the user updates with potentially large amounts of data, only to have the new version of the product delete the entire database. It's not clear to me how your app deals with updates (do you want that added button/label just to be completely lost, or do you save them in some way?) so recommending a solution is difficult, but maybe you need an uninstall custom action to delete the database, or on an upgrade you add the updates to the existing DB instead of removing it and starting again.
I found a solution. The file wasn't updating because the modified date had changed.
From MSFT site:
Nonversioned Files are User Data—If the Modified date is later than
the Create date for the file on the computer, do not install the file
because user customizations would be deleted. If the Modified and
Create dates are the same, install the file. If the Create date is
later than the Modified date, the file is considered unmodified,
install the file.
Since I had two Access databases (front-end with the forms, backend with the data tables) and needed only one to be updated (the frontend where the forms are), here's the workaround:
1) Change REINSTALLMODE property to amus instead of the default omus. It will force the reinstallation of all files. To do that, I used a PostBuildEvent as explained here.
2) Set the backend file property Permanent to true
3) Add a Launch Condition: Search Target Machineto check if the backend file exists on the computer. Name it something like BACKENDEXISTS
4) Add a Condition value to the backend file in the File System view to install the file only if it hasn't been found by the Launch Condition. In this case, it will be not BACKENDEXISTS. If this is a first install, it will install the file because it hasn't been found. If this is an update, it will find the file because of the Permanent property and will not replace it.

Core Data hoses itself

Periodically I launch my app from Xcode to find Core Data errors due to an empty model file. The versioned model files are found in the main bundle but the model file still inits to nil. See my answer for partial workarounds but no solution to date.
I've verified that the files exist and are accessible using the access function. I've tried using initWithContentsOfURL and mergedModelFromBundles with the same result.
This happens randomly and I suspect something is changing the model file behind the scenes but I don't know what.
Restarting my computer seems to have solved the security related crash but this also necessitates removing the existing Core Data store file as it complains the existing one doesn't match the model file.
[UPDATE]
Restarting does not solve the problem. But reseting the current version of the Core Data model file did the trick. I changed it to an older version and then back. This question helped me think of this as something to try. Using mergedModelFromBundles: and versioning (CoreData) Still not sure what the root problem is.
[ANOTHER UPDATE]
I put a file monitor on the .xccurrentversion file in my Core Data momd file bundle to observe when the file is being touched. I've noticed that XCode (or some build tool) updates the .xccurrentversion file periodically when XCode comes to foreground (either when the project is opened or when it's been in background for a while). When it did this today it updated the file setting _XCCurrentVersionName to the main momd file bundle rather than the version file. I replaced the .xccurrentversion file with an older version and it launched. This would explain why reseting the current model version fixes this issue. I have no idea what the conditions are for XCode to update this file.

Can Xcode ask / react to file changes outside of the IDE?

Is there are means whereby if files are altered outside of Xcode, that a warning in can be shown to ask if you want to refresh the file? This feature is available in Visual Studio, for example.
As a temporary solution, were working on source files in a Dropbox folder.
Although growl notifies us that some files has changed, Xcode doesn't know about these changes.
No, Xcode won't do that, and since there's no support for plugins you're pretty much stuck with that behavior. Some suggestions:
Create a local git repository (Xcode can do this for you when you create the project, I don't know if you can do it once it is created.
Use another IDE, like AppCode (this isn't even a solution, just came to me and I decided to add it).
With a version control system you can see the little 'M' on edited files, browse changes, etc. But since you wrote that this is a temporary solution I bet you already know this.

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