SAF: App Inventor implementation of Storage Access Framework

Extensions
13

Example 2

  1. Open document picker and create document

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    image1036×450 46.8 KB

    (Since you now know how to take persistable permission, so I'll skip that part)

  2. Read and write to document

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    image761×463 29.9 KB

  3. List files

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    image973×435 44.6 KB

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14

Developers might also find these links about SAF useful in addition to your nice explanation.

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15

Thanks @vknow360 for your explanations, making more sense now as to what one can do with your extension.

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16

Well I have fallen at the first hurdle....

Following your first image, when I click the button I am taken to the device's default file manager (or what looks like it), I went to the root folder, the file manager asked me to give permission to this area (to MIT Companion App), then returns me to the project with this error:

image

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17

I forget to mention that direct child's id should be obtained using GetTreeDocumentId method.

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18

Sorry, I used the wrong block :upside_down_face:

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19

OK that all works. :+1:

Is there no way then, in order to get started, other than the user going into their file manager and granting a permission, to get the root or other folder (tree)? (Open Document Tree)

Perhaps a uri for the ASD ?

I can see how one can traverse through a file list to find sub (folders) trees, and then list files again and so on. An image component accepts a content uri to display an image. Is this going to be the same for other components needing a file?

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20

No, user must grant access through Documents Picker.

I am not sure about this.
Image component works fine.
Same should be correct for audio and video player.

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21

Understood :slight_smile:

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22

SAF is only needed for → non-media files. Media files (jpg, png, mp3, m4a, mp4,...) can be accessed from all paths (outside of the ASD or privateDir) with READ permission.

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23

The question was just about the content uri being read by other components, e.g. it works with the image component:

image
image708×42 6.3 KB

not had a chance to test some of the others yet.

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24

Could you please provide an example of how one uses the flags in order to set persistent permissions? I presume this saves the user having to visit the document picker again when restarting the app?

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25

With this extension you really have to bite through and some users might lose teeth in the process. :wink: :grinning:

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26

I am prepared to champion those users, in order to save their teeth ;), and ask Sunny how all the various elements of this extension work.

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27

Sure, here it is:

Also data gets kind of binded to the app and you don't lose access to it even after multiple reboots.

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28

Epic work :star_struck: :+1:

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29

Thank you..:+1:

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30

What is the syntax for setting an initialDir?
image

Whatever I put in here, I am just taken to the last location I selected in the document picker ?

Ah, i just tried a full uri and this worked, e.g.

content://com.android.externalstorage.documents/tree/primary%3A/document/primary%3AMusic

opened at the Music folder

will this part be the same on all devices:

content://com.android.externalstorage.documents/tree/primary%3A/document/primary%3A

If I select the ASD I get a different path:

content://com.android.externalstorage.documents/tree/primary%3AAndroid%2Fdata%2Fedu.mit.appinventor.aicompanion3%2Ffiles/document/primary%3AAndroid%2Fdata%2Fedu.mit.appinventor.aicompanion3%2Ffiles

this is all using the companion...

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31

Yes, it doesn't matter whether there is an empty string or a special path there.

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32

... and you cannot select

  1. the root dir of the external storage /storage/emulated/0 and
  2. /Download

But you can select /Downloads.

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