Can we notify Polymer about changes once entire patch applied?

[miyconst]

It is very bug prone when Polymer observers are hit in between of patch items.

cc @warpech, @tomalec

[warpech]

I'd rather avoid it, because then the client side code becomes aware of Puppet.

Can you give any examples when its really unavoidable?

As a workaround, perhaps you can have a property Updated: 0 that is incremented on the server and set the observer on it?

[miyconst]

I'd rather avoid it, because then the client side code becomes aware of Puppet.

Just opposite. It should be hidden into the puppet-polymer-client. Currently we have to be aware that the view-model can get into inconsistent state at any moment and care about it in every web component.

The last case which raised this issue:

<palma-d3-matrix rows="{{model.Rows}}" cols="{{model.Cols}}" cells="{{model.Cells}}"></palma-d3-matrix>

The Rows, Cols, and Cells arrays are updated on certain user action. Now the problem is that palma-d3-matrix observes changes on those values and expect to have cells for existing rows and cols. What happens in reality is that polymer notifies palma-d3-matrix about Cells change before the Rows and Cols have actually been updated.

Even more weird staff happening when partial.Html property is involved.

[warpech]

What version of Starcounter and puppet-polymer-client are you using? Current version uses notifyPath (see https://github.com/PuppetJs/puppet-polymer-client/blob/gh-pages/puppet-client.html#L467) after all of the sequence operations are actually applied.

[miyconst]

You are right. After some more digging and investigation I found that my issue is caused by the following:

• Client receives a patch to replace a partial.
• PuppetJs applies view-model changes.
• puppet-polymer-client notifies Polymer about the changes.
• Polymer applies the view-model changes to the old HTML.
• Exception happens here, as the old HTML is not designed for the new view-model.
• starcounter-include removes old HTML.
• starcounter-include loads new partial.

[miyconst]

I have created a simplest possible example in my Playground.

In the example I have two partials with { "Date": "" } property defined, loading one after another will apply the new value to old HTML first and only then replace the entire partial.

Steps to reproduce:

1. Clone the repository.
2. Start Playground app.
3. Open http://localhost:8080/playground.
4. Open Chrome Console.
5. Click [Load date page] button.
6. Click [Load sub page] button.
7. The DatePage partial will throw an exception because the value from SubPage was applied to it.

Replace console.error with debugger if you want to stop for debugging.

[tomalec]

For the first look, it seems to me like a bug (missing scenario coverage) in starcounter-include (juicy-html). Could you provide an example of a patch received by client?

[miyconst]

@tomalec here is the patch:

[
  {
    "op": "replace",
    "path": "/_ver#s",
    "value": 3
  },
  {
    "op": "test",
    "path": "/_ver#c$",
    "value": 2
  },
  {
    "op": "replace",
    "path": "/SubPage",
    "value": {
      "Playground": {
        "Html": "/Playground/SubPage.html",
        "Date": "SubPage",
        "Items": [ "i7-4790k", "i7-5820k", "i7-6700k" ],
        "SelectedItem$": "",
        "Details": { },
        "Remove$": 0,
        "Add$": 0,
        "Message": ""
      }
    }
  },
  {
    "op": "replace",
    "path": "/LoadSubPage$",
    "value": 0
  }
]

Can you look at my example? It is tiny and easy to understand.

[warpech]

Let's look at this when Polymer 2.0 integration is tested in Starcounter 2.4.