How to deal with database, historian, not loaded

In perspective, is there a way to deal with the below?

I got a requirement, to display "page error, retry" popup, when, for some reason,
connectivity to database/historian is loss, thus on page, data are not completely loaded and show Null.

In this age where application is driven by data source that are stored remotely.
I hope there is a way to check that something when wrong, and will raise popup: "something went wrong, please refresh".

Of course, but the how of the answer is a bit vague based on the information you have provided.

Is this specifically for the entire project or is it for a specific view or component?

There are various way that a lack of connectivity to a data source will present itself and depending on how you are accessing that, the way you can detect it can vary.

For instance you could use a Gateway Scheduled or Timer Event in conjunction with system.db.getConnectionInfo() to show a global popup.

Thanks, I guess that is the way.

For now, On page startup, after few seconds, check if value is Null and check connections..

On my case, I am loading data both from DB and historian, I should check connection of both, and allow user to refresh in case of Null.

I guess, I also could run a Now() binding, for timer event, to check connection continuously and raise/hide a popup when data is bad/good.

The Expression Language now() function defaults to 1000 ms poll rate. You can specify a rate in milliseconds such as now(3000).

It is a way. The way would depend on your exact needs.

This terminology is quite possibly mixed.

The historian is not always a separate database connection. In fact I would say in most circumstances they are the same "connection"*. It doesn't have to be, by any means, but most often is.

*Ignition actually used a connection pool, so they wouldn't have the exact same connection but rather be connected to the same endpoint.

I agree, that in most cases Historian is pointing to database as well.
So down in database is also down in Historian.

But we are using Canary as historian, and I don't know how it was configured.

In gateway config, I see both database and historian has Status Indication.

Any idea how to get historian status?