Is there a way of Sharing a URL for a panel's state?

Panel
1

Some times a user of a panel dashboard has set all the widgets to display a eureka plot of their data.
They would then like to share an URL that captures that eureka state of the panel. When the URL is resolved, it returns a new instance of the panel dashboard in that eureka state.

I think creating this URL would involve encoding the state of all the widgets in the URL, something like:
https://www.test.com/panel.py?widget1=value1&widget2=value2

When the panel restarts, it extract the initial values of the widgets using:
pn.state.session_args:

Is there a function or shortcut to save the state of all of a panel’s widgets?

1 Like
2

This has been merged into master but not released yet. See https://github.com/holoviz/panel/pull/1150

I’ve contributed a Location component that will enable updating the url with parameters and reacting to changes in the url. @philippjfr has improved this.

The one thing remaining is “serializing” the parameters of a param.Parameterized class into the parameter part of the url and vice versa. But this is standard python functionality (I don’t remember where though :-))

I really need the Location component. Would be so powerful for my users to be able to bookmark and share links to the exact state of their apps and views.

3

This was merged as part of the Location component. Specifically you can call pn.state.location.sync(parameterized, parameters) and the declared parameters will be bi-directionally synced with the URL.

2 Likes
4

The sync functionality sounds so cool @philippjfr. Can I change the parameterized and parameters when I change my “page” in an application with multiple pages?

5

Depends on what you consider a page in your case a “page” is still the same app right? I think you might have to unsync in that case (which is functionality I’d have to add).

1 Like
6

Yes its the same app @philippjfr

7

Okay, would you mind filing an issue about an unsync method?

8

Done: Please add functionality to change the parameters to sync via the Location component · Issue #1335 · holoviz/panel · GitHub

9

Thank you, you guys.
I see that pn.state.location is briefly described in the current check in of the panel documentation.

10

If you have suggestions on improving the visibility of that documentation and/or want to make a PR that would be super helpful. Examples that use the functionality would also be super helpful.

11

Hello folks,

I was just curious if there was ever an update on the examples that use this state. I have developed a rather complex dashboard using param class, and would definitely love to send the URL that captures the state of my widgets to the stakeholders. Is there a good example on how I need to modify my app to achieve that ?
Even a button “Generate URL” would work…

Thanks,
Anton.

12

Check out https://panel.holoviz.org/gallery/simple/sync_location.html#simple-gallery-sync-location

13

Thanks for the pointer. Are there any limitations as to certain widgets not being able to serialize yet ?

1 Like
14

I would not know. But try it out and report back :slight_smile:

15

Hello Marc,

I have checked out the example, and am now puzzled as to how to port it to the dashboard developed as a Param class instance.

16

@Marc

I got somewhere via the following, but it kinda looks hacky, and I do not like using a pre-set index for the widget corresponding to a parameter. Is there a nicer way to do it?

import panel as pn
import param


class ReactiveDashboard(param.Parameterized):
    widget = param.Range(bounds = (0,10))
    widget2 = param.String(default='Text')
    widget3 = param.Integer(10)

    def panel(self):
        result = pn.Row(self.param)

        # if pn.state.location:
        #     #pn.state.location.sync(self.param.widget2)
        #     # pn.state.location.sync(self.widget2, {'value': 'text_value'})
        #     # pn.state.location.sync(self.widget3, {'value': 'value'})
        return result

res = ReactiveDashboard().panel()
if pn.state.location:
    pn.state.location.sync(res.objects[0][2],{'value': 'text_value'})
res.servable()
17

For whoever gets stuck like myself, here is the solution that actually works, and does not look too hacky (in hindsight):

One oustanding question though perhaps to @philippjfr or @Marc - where should I plug in the syncing part - within my class method or outside of it (right before servable) ?

It also does not seem to work if I sync >2 parameters. Perhaps has something to do with picking the first match instead of the one with the right name:

  File "/home/anton/miniconda3/envs/oracle-telescope/lib/python3.8/site-packages/panel/io/location.py", line 124, in _update_query
    serialized[matches[0][e.name]] = val
KeyError: 'widget3'

Is there a way to pass custom json serializer ? I have some of widgets that are datetime and default json encoder does not like datetime.

class ReactiveDashboard(param.Parameterized):
    widget = param.Range(bounds = (0,10))
    widget2 = param.String(default='Text')
    widget3 = param.Integer(10)
    def panel(self):
        result = pn.Row(self.param)
        if pn.state.location:
            pn.state.location.sync(self, {'widget2': 'text_value'})
        return result
res = ReactiveDashboard().panel()
res.servable()