One of my favourite tricks to use on a dashboard is to show the Last Refreshed Date.  This is important as it lets you know how stale your data is.  I think it’s even more important with Power BI, as it tells you if your automatic refresh is actually working!

Last Refreshed Date for Power Pivot

I’ve actually covered this topic in the past for Power Pivot solutions. You can find that article here if you’re interested.

Display the Last Refreshed Date in Power BI

Generate Last Refreshed Date with Power Query

Unlike the previous article, to work with Power BI, we need to generate the Last Refresh date ourselves using Power Query.  No big deal, it is as simple as this:

• Open PowerBI Desktop
• Get Data –-> Blank Query
• Go to Home –> Advanced Editor and replace the code in the window with this:

let
Source = #table(type table[LastRefresh=datetime], {{DateTime.LocalNow()}})
in
Source

• Click Done and rename the query “LastRefresh_Local”
• Click Close & Apply

This code makes a nice little table that returns the current date and time each time we refresh the solution.

Create the Last Refreshed Measure

To finish it off, we need to create a simple measure and add it to our dashboard.

• Go to your Report window –> New Measure –> Define it as follows:

Last Refreshed (Local) = FORMAT(LASTDATE(LastRefresh_Local[LastRefresh]),"mmm dd, yyyy hh:mm:ss AM/PM")

• Now let’s create a Card visual to hold it:

So far everything looks really good here.  The card is formatted nicely, and I updates to the current date and time every time I hit the refresh button.  It’s a thing of beauty!  What could possibly go wrong with this?

Publishing to the Power BI Service

Encouraged with our visual, we’ll now publish it to Power BI:

• File –> Publish –> Publish to Power BI
• Login to the Power BI service and scroll down to the Datasets area

At this point you should click the little … to the right of the dataset you uploaded (whatever you called it) and click Refresh.  It will prepare for a bit, then should refresh.  If your experience is anything like mine, your report shows this:

At first, you think “Hey cool!” until you realize that this is the data – to the second – of your original upload.  So even after you refresh the data set, you need to refresh the report:

And when you do, you get this:

Um… WHAT?  That’s 7 hours different!  How is this possible?

So I’m in the Pacific time zone, which is currently UTC-7.  (We are UTC-8 when we are not on daylight savings time.)  So apparently the date that is showing here is giving me the UTC date.

This really sucks, obviously. I was really hoping that the dates and times would show based on my browser settings or something, but obviously not.

I tried a bunch of things to fix this, including forcing the column to a DateTimeZone data type, but that made the DAX formula choke, as it only accepts DateTime data types.  I tried various combinations using DateTimeZone.UtcNow(), DateTimeZone.LocalNow(), adding periods, subtracting them and more.  The killer though was that as soon as the time zone got removed (which is necessary for the DAX measure to work), Power BI displayed the time assuming it was UTC. So the issue I’m seeing here is that – no matter the DateTime you feed Power BI – it thinks it has the same time zone as the server.  Not so good.

How to Display the (Correct) Last Refreshed Date with Power BI

Just to be clear here, the title above is actually a heinous misrepresentation.  The timestamp was correct, it’s just being interpreted incorrectly by Power BI (but not Power BI desktop).  So I had to fake it out.

I reached out to Chris Webb for his thoughts, and he suggested hitting an API.  I’d already tried looking for a page, but picked up on this API which turned out to be quite useful:  http://www.timeapi.org  Even more interesting is that both www.timeapi.org/pst and www.timeapi.org/pdt return the same thing.  I’m hoping that this means it is going to allow me to survive daylight savings time with no adverse impacts…

So armed with that, I decided that the only way I was going to get this to work was to pull back the UTC offset, and add it to my date.  That effectively returns a bogus date that Power BI will represent in UTC to match my time zone.  Complicated, no?

Collecting the Current PST Date/Time

I don’t think I’m going to clearly document all the steps for this, as that would make this article really long.  Instead, here’s how you can implement this:

• Create a new Blank query and paste this code in the Advanced Editor

let
Source = Web.Page(Web.Contents("http://www.timeapi.org/pst")),
Data0 = Source{0}[Data],
Children = Data0{0}[Children],
Children1 = Children{1}[Children],
#"Removed Other Columns" = Table.SelectColumns(Children1,{"Text"}),
#"Inserted Last Characters" = Table.AddColumn(#"Removed Other Columns", "Last Characters", each Text.End(Text.From([Text], "en-US"), 6), type text),
#"Changed Type2" = Table.TransformColumnTypes(#"Inserted Last Characters",{{"Text", type datetimezone}}),
#"Replaced Value" = Table.ReplaceValue(#"Changed Type2",":00",".0",Replacer.ReplaceText,{"Last Characters"}),
#"Replaced Value1" = Table.ReplaceValue(#"Replaced Value",":30",".5",Replacer.ReplaceText,{"Last Characters"}),
#"Changed Type1" = Table.TransformColumnTypes(#"Replaced Value1",{{"Last Characters", type number}, {"Text", type datetime}}),
#"Added Custom" = Table.AddColumn(#"Changed Type1", "LastRefresh", each [Text]+#duration(0,Number.From([Last Characters]),0,0)),
#"Removed Other Columns1" = Table.SelectColumns(#"Added Custom",{"LastRefresh"}),
#"Changed Type" = Table.TransformColumnTypes(#"Removed Other Columns1",{{"LastRefresh", type datetime}})
in
#"Changed Type"

• Click Done and rename the query as “LastRefresh_API”
• Click Close & Apply

The basic gist is that it does the following:

• Pulls the web page and drills into the single cell we need
• Splits off the time zone information, replacing the minutes with fractional hours and turns it into a decimal number
• Extracts the original date/time (without the time zone) and adds the time zone offset to that value.  This essentially subtracts 7 hours from the original date for me right now
• Performs as bit of cleanup to drill into the faked date/time we need

(If you want to use this for your time zone, I believe all you should need to do is change the “pst” portion of the URL to your time zone name.)

Create a new Last Refreshed Measure

Creating this measure is pretty much the same as the last one.

• Go to your Report window –> New Measure –> Define it as follows:

Last Refreshed (API) = FORMAT(LASTDATE(LastRefresh_API[LastRefresh]),"mmm dd, yyyy hh:mm:ss AM/PM")

• And create a Card visual to hold it

You should now have this odd looking contrast:

Great, except that… it is 3:22 PM for me, not 8:22 AM.  But fine, whatever, let’s publish this and see what happens.

Publishing to the Power BI Service

To publish the file, we take the following steps again:

• File –> Publish –> Publish to Power BI
• Confirm that we want to overwrite the data set
• Login to the Power BI service and scroll down to the Datasets area
• Click Refresh Now

At this point you might be told you can’t as you haven’t provided credentials to the data set.  Just Sign In as Anonymous and you’ll be fine:

And of course, now we can refresh the Report as well.  And when we do…

As you can see, the API version is showing the correct time here, not the Local version.

Takeaways

The biggest takeaway here is that you have to care about how your audience is using your files.  If you are going to deploy your reports by emailing *.pbix files around the company, the setting up a table using the DateTime.LocalNow() will work great.  But if you are going to publish your files to the web… that obviously throws in some wrenches.  Here’s a side by side view of those two alternatives:

Probably the most frustrating thing to me is that I was trying to find a solution that will show it correctly in BOTH Power BI Desktop and Power BI Online.  There’s nothing worse than working with a report you know is broken depending on where you look at it.  🙁

PBIX File

If you want the file so that you can try it out in your own PowerBI service… here you go.  🙂