Internal url handler for referencing other entries

[networkException]

Summary

Add a url sceme for referencing other entries.
This request would make use future html support with the anchor tag.

Examples

For this example I'm using a simple database structure:

The entry "github" is nested inside the group "accounts", which itself is nested inside "root".
In the advanced edit widget there is an additional attribute called "backup codes".

<!-- The path specified specifies an entries location -->
<a href="keepassxc://root/accounts/github/">Opens the main edit widget of "github"</a>

<!-- ... or opens a group. -->
<a href="keepassxc://root/accounts/">Show the "accounts" group</a>

<!-- If the path "ends" and there are no other parameters, 
its possible to just highlight the target group or entry in its parent "scope" -->
<a href="keepassxc://root/accounts/github/?outer=true">Opens the entry's parent group and focuses "github"</a>

<!-- Continue the path to show a specific widget in an entry -->
<a href="keepassxc://root/accounts/github/main/">Opens the main edit widget of "github"</a>
<a href="keepassxc://root/accounts/github/advanced/">Opens the advanced edit widget of "github"</a>
<a href="keepassxc://root/accounts/github/history/">Opens the history edit widget of "github"</a>

<!-- As the advanced area has two subwidgets which have named subentries, 
they can continue the path as well -->
<a href="keepassxc://root/accounts/github/attributes/">Opens the advanced edit widget of "github"</a>
<a href="keepassxc://root/accounts/github/attachments/">Opens the advanced edit widget of "github"</a>
<a href="keepassxc://root/accounts/github/attributes/backup%20codes/">
    Opens the advanced edit widget of "github" and selects the "backup codes" attribute
</a>

<!-- If the path leads to some sort of text area, 
there are parameters for going to some specific line and column -->
<a href="keepassxc://root/accounts/github/main/note/?line=2&column=4">
    Some line and column in the notes of "github"
</a>
<a href="keepassxc://root/accounts/github/attributes/backup%20codes/?line=2&column=4">
    Some line and column in the "backup codes" attribute of "github"
</a>

I'm open for more suggestments / adjustments to the sceme

Context

This feature could allow users to further organize their database.
For example someone might have one entry for payments, but they for example still want a reference
for all payments made on github in their github account entry.

[OLLI-S]

Good suggestion, I suggest an enhancement:
Instead of the scheme keepass: the scheme keepassxc: should be used.

So this will be (taking the first example above):

<!-- The path specified specifies an entries location -->
<a href="keepassxc://root/accounts/github/">Opens the main edit widget of "github"</a>

[networkException]

Yea ok that seems reasonable, I will change it in the examples

[droidmonkey]

We should make it application agnostic in case others want to implement it. Recommend something like entryref://[uuid | path]/[attribute] and groupref://[uuid | path]. This could become a replacement to the attribute reference schema as well.

[networkException]

If others want to implement it I would say that the sceme should just be keepass. However specifying the "type" of entity (group, entry, etc.) in the url is something I would add as well.

I was thinking of using the tld as the type of identifier used and the sld as the type of entity referenced.

<a href="keepass://group.path/root/accounts/">Opens the "accounts" group by path</a>
<a href="keepass://entry.uuid/21ea1457b4ec418496d1811b0a9b67cb/">Opens the "github" entry by uuid</a>

As soon as there is agreement on this I will rewrite the main comment and work out a full specification.

[droidmonkey]

Using the tld is clever, go ahead and write up the final proposal.

[networkException]

Alright here it is keepass-url-spec.md. I'm happy to take any feedback because this is really the first time I've written something comparable

[droidmonkey]

Hmmmmm, couple points, then I will show some changes through examples.

1. The root group is never spelled out in our path conventions, we always start simply with /
2. An action should be in the query string, this allows the crafter/reader of the URL to flow from left to right:
   keepass://[attribute]@[object-type].[ref-type]/[ref]?[action(s)]#[anchor]

<a href="keepass://group.path/accounts/">Show the "accounts" group</a>
<a href="keepass://entry.path/accounts/github/">Focuses on the entry in it's parent group</a>

<a href="keepass://entry.path/accounts/github?edit">Opens the main edit widget of "github"</a>
<a href="keepass://entry.uuid/21ea1457b4ec418496d1811b0a9b67cb?edit">Opens the main edit widget of "github"</a>

<a href="keepass://entry.path/accounts/github?edit#advanced">Opens the advanced edit widget of "github"</a>
<a href="keepass://entry.path/accounts/github?edit#history">Opens the history edit widget of "github"</a>

<a href="keepass://entry.path/accounts/github?attribute=backup%20codes">
Opens the advanced edit widget of "github" and selects the "backup codes" attribute</a>

<a href="keepass://backup%20codes@entry.path/accounts/github">
Opens the advanced edit widget of "github" and selects the "backup codes" attribute</a>

<a href="keepass://entry.path/accounts/github/?attribute=Notes&line=2">Select line 2 of "github" notes</a>

<a href="keepass://entry.uuid/21ea1457b4ec418496d1811b0a9b67cb?customdata=_LAST_MODIFIED">
Hightlights the "_LAST_MODIFIED" key value pair in the plugin data widget</a>

<a href="keepass://db.uuid/34eb1447b7ec218446d1451b0c9b49a1?entry=21ea1457b4ec418496d1811b0a9b67cb&attribute=Password">
Go to open database with uuid 34eb1447b7ec218446d1451b0c9b49a1 open the entry with 
uuid 21ea1457b4ec418496d1811b0a9b67cb and highlight it's password</a>

I would love this syntax to replace/augment the {REF:...} syntax. For example, to fill the password from an entry: keepass://Password@entry.uuid/21ea1457b4ec418496d1811b0a9b67cb

I am in favor of supporting a scheme like dbref:// in addition to keepass://.

[networkException]

I actually didn't know that you can't name an additional attribute "Title", "Password" and so on, so a distinguishment between integrated and additional as the attribute type isn't really nessesarry

1. I wasn't really sure about root, for me it just looked like a group that is contained in the actual root of the database, but I might be wrong. (here a picture of the entry of the example database I used)
   
2. I quite like that change because it indeed makes the url more readable.

I opted for choosing the third level domain to specify the attributeType because a user might have an attachment called "Notes", which then would make the attribute "Notes" inaccessible. Same goes with custom / plugin data. I like the keepass://backup%20codes@entry.path/accounts/github syntax as well but it doesn't specify that type.
Should the attributeType just be left out and risk it being ambigous? Should some other segment be used? And should this just replace the entries history?

Another thing I am not completely sure about is
keepass://db.uuid/34eb1447b7ec218446d1451b0c9b49a1?entry=21ea1457b4ec418496d1811b0a9b67cb#Password.
Having db as an entity type surely isn't a bad idea, but this exact example brings makes both the reference type and the attribute type ambigous. I am not sure if this should be possible as an entry in root with the name "21ea1457b4ec418496d1811b0a9b67cb" might not be possible for example. Same goes with an attachment named "Password". Also I was wondering if db.path/home/user/desktop/keepass.kdbx should be allowed.

Suppporting dbref:// seems reasonable as well.

[droidmonkey]

Attributes are all the same. There are a few reserved names. You can see them in EntryAttributes.h

[networkException]

alright I see

[droidmonkey]

I realize you are comparing attachments and attributes. Those are two completely different aspects of an entry. To reference an attachment by name I would craft this url:

<a href="keepass://entry.path/accounts/github/?attachment=notes.txt">Select attachment "notes.txt" of github entry</a>

I modified my examples above to actually use the query string as intended.

[networkException]

So what I'm still wondering about is the syntax for history items. In my scheme I used the part before the @ (which is now used for attributes) to reference them by timestamp. Should this not be implemented at all or should I use some other url segment for it?

Additionally, the db entity type still causes some headache for me, as this url doesn't specify the referenceType of the entry.
keepass://db.uuid/34eb1447b7ec218446d1451b0c9b49a1?entry=21ea1457b4ec418496d1811b0a9b67cb&attribute=Password.

The following would be my approach

<a href="keepass://Password@db.uuid/34eb1447b7ec218446d1451b0c9b49a1/?entry.uuid=21ea1457b4ec418496d1811b0a9b67cb">
Go to open database with uuid 34eb1447b7ec218446d1451b0c9b49a1 open the entry with 
uuid 21ea1457b4ec418496d1811b0a9b67cb and highlight it's password
</a>
<a href="keepass://Password@db.uuid/34eb1447b7ec218446d1451b0c9b49a1/?entry.path=/accounts/github/">
Go to open database with uuid 34eb1447b7ec218446d1451b0c9b49a1 open the entry with the path /accounts/github/ and highlight it's password
</a>
<a href="dbref://db.uuid/34eb1447b7ec218446d1451b0c9b49a1/?entry.path=/accounts/github/&attribute=Password">
Go to open database with uuid 34eb1447b7ec218446d1451b0c9b49a1 open the entry with the path /accounts/github/ and highlight it's password
</a>
<a href="dbref://db.uuid/34eb1447b7ec218446d1451b0c9b49a1/?entry.path=/accounts/github/&attachment=notes.txt">
Go to open database with uuid 34eb1447b7ec218446d1451b0c9b49a1 open the entry with the path /accounts/github/ and highlight a file named "Notes.txt"
</a>

[droidmonkey]

History of entries should be referenced through the query string: keepass://entry.path/accounts/github?edit&history=[timestamp|index] this will open the entry edit view of the particular history item. You can reference history by explicit timestamp or index (0 = current, 1 = previous, 2 = ...)

I like the entry.uuid and entry.path query selectors for the db entity, keeps it consistant.