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nirvana_moksh
Level: Powered On

PowerApps Writing back to SQL?

I have an app which is up and running and writes back to Excel Online hosted on OneDrive. We do not find this a secure way as we have to give users of the Power App edit access to the Excel Online as well to successfully make the comment/write back.

 

We want to replace this with a On-Prem SQL Server Table. I am unsure of what rights are needed for the SQL Table besides reader and writer and how to go about replacing this Excel Online connection and how to go about making this happen. 

 

Any documentation/advice would be really helpful.

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johnmarlowe
Level: Powered On

Re: PowerApps Writing back to SQL?

My suggestion was a bit of a raw principle, but as I sat and thought there are a few ways you could do this i guess. So you could create a table that stores execution of SP'S. In your SP open with creating a record and flagging a Procedure started column. (Set the record ID as max(ID) +1 and store that value within the SP so it can be called at the end. Make sure you put this first part in a transaction and commit before executing the main part of the SP so that you definitely have a record of the proc starting even if it falls over later . At the end update the original record in a Procedure complete flag column. You theft have a full record of procedures failing to fully execute. Useful for debugging. You could even store all parameters passed to the proc in this execution table as this might also.help debugging.

As to how you get this info back to the PA user, it's never going to be as ideal as a Proc failed message immediately after execution of the flow, but it's a start.
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johnmarlowe
Level: Powered On

Re: PowerApps Writing back to SQL?

For what it's worth I recommend this approach based on my own experience. Not only is it more secure but infinitely more flexible. The app I've build pulls in Information from other DB servers which in turn pulls data from 3rd party software api's which means we can use Powerapps to bridge the gaps in off the shelf software and provide the bespoke elements without the need for costly supplier development.

If you intend to do this you will need to.set up a gateway on your network, but ideally as closet to, if not on the DB server (which no allows clustering of multiple gateways, to ensure good availability to your DB) to minimise latency. Our DBA set up the gateway, and although it took a little fiddling to get it working it was fairly straightforward.

One recommendation i would make is that rather than use the standard data links to your data source from within powerapps, that you play around with passing the edits through sql server stored procedures using Flow. This actually gives you a lot more flexibility, and security.
The gateway itself uses the specific SQL server user account details, however if you use stored procedures and pass the user name over as a parameter your stored procedure offers you no end of options for storing information related to the auditing of data.
You might find this takes a bit of time and someone who's comfortable at writing and adapting stored procedures, but I promise it's worth it as you engage the power of the DB rather than complicating your webapp front end.

Anyway, good luck to you in your endeavours.
nirvana_moksh
Level: Powered On

Re: PowerApps Writing back to SQL?

thanks a lot for your reply John, I will surely try this out and discuss with my team.

bbrazeau
Level: Powered On

Re: PowerApps Writing back to SQL?

+1 on John's suggestion to use Stored Procedures.

 

You can limit the SQL account to just executing the necessary procedures, no need to grant Insert/Update on the underlying tables.

 

The SP enforces data types and can have additional logic to validate the data.

 

Is easy to update if business rules change or underlying tables are restructured.  The SP may look the same to the PowerApp/Flow thats using it but it can be completly rewritten - meaning you don't have to rejigger those applications when things change in the database.

johnmarlowe
Level: Powered On

Re: PowerApps Writing back to SQL?

This is a great point. Once you've established your SP execution point you can effectively use it as a static API endpoint for posting data. At first I passed every piece of data as a separate parameter to the SP but each time I wanted to pass a new field I had to fiddle with the flow. Instead what I do now (generally) is pass all data fields across in a single string with my own syntax to delimit the data. I then have logic in the SP to split out the data into separate fields and update accordingly.
I still generally pass the username over as a separate parameter because generally any time someone edits the data I want to make an audit record so i'm always needing a username.

Like I say, this has taken some time to get to and you want to be comfortable with SQL, but having worked with lots of professional software suppliers who seem to give the front end too much of the data logic responsibilities, I'm a big fan of leveraging the massive capabilities of a DB like MSSQL in doing the heavy lifting, leaving your App to be nimble and user-friendly.
It gives you the advantage to develop the front and back ends on different release schedules.
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nirvana_moksh
Level: Powered On

Re: PowerApps Writing back to SQL?

So this is how my Power Apps looks like as of now which is connected to Excel Online and each of the sections in this screen like 'Type' , 'Date', 'Description' write back to the Excel Online. Additionally, I have considered the route of developing the stored procedure that has parameters capturing these details.

 

So my question is how do i define any kind of stored procedure within these 'data cards'/sections to write to the sp, is it just like changing the connection to SQL? I know I can connect to SQL but then it lists out Tables where I want these data cards to write back to, so I am kinda lost. 

 

Power Apps.PNG

Super User
Super User

Re: PowerApps Writing back to SQL?

I will offer here is my step-by-step guide for deploying the gateway and building your first app from SQL. Might help you get started and avoid some of the gotchas with licensing and such. 

Shane - Microsoft MVP, YouTube, and PowerApps Consulting for when you are in a bind to get this fixed quickly. And finally we now have PowerApps Training
johnmarlowe
Level: Powered On

Re: PowerApps Writing back to SQL?

So my own personal approach has been that instead of calling the main table to display (say firstly in a gallery and then the selected record in data cards) I use a database view (which poweapps now supports). Even if the view is just all unfiltered records and all columns from your table (i.e. identical to your core data table) to begin with. There main advantage here is the ability to control what information powerapps sees, but to do it from the database side. So for example...
If you ever want to soft delete a record you can add a simple bit column (isDeleted) into the table, but change the view so it filters out any of the deleted records (i.e. where isDeleted <> 1) and this way you never need to put that logic into your powerapps gallery filter.

Or if you want to join info from another table on, you can do this in the view without having to add and store additional field data in your core record.

So assuming you have your view set up and this is what's coming into.your gallery and being displayed in your sections, you just need to decide exactly how you go about the editing process for the users. But however you want to do this you need to make sure you create a SP in the database that accepts the parameters you want. So let's keep it conceptually simple, we create a SP that accepts parameters for each field you might potentially want to edit in an update. Let's say this is proc_tableUpdate. All parameters are set to NULL maybe which gives you the option of passing only changed values of the record. However if you want to pass over all values to the procedure that's not a problem it's just a case of whether you want to limit the data going across.

Your SP should just effectively be a UPDATE statement. It takes the values you pass it and updates the core record table (and does whatever else you want it to e.g. create an audit record of the change)

To access this SP from Powerapps you need to set up a flow from your powerapps home page, look for the Execute SQL Server stored procedure connector, and then if your gateway is up.and running correctly you should see your SP. the final set up for the flow will ask you to define the parameters but you click on "ask in powerapps" for each parameter space. You can assign a flow to an ON SELECT action in Powerapps, and you then give it the values from your powerapps items, such as drop downs, input boxes etc. The point is here that there are a million and one ways of designing this kind of interface then, and it just depends on your preferred way if setting it up. But ultimately the desired values go.into the flow as parameters and are therefore passed through the gateway to the SP as such.

So things I didn't touch on there are adding new records:
You can either do this using the same SP but use a MERGE function to distinguish between an update or an insert (or you can manually simulate this but SQL server's merge function is pretty valuable)
OR you can set up a separate SP (with an insert function) and flow to handle the insert of a new record of your PA process is different for updates and new records.

The other thing is that eventually you may just want to pass through a single string to your SP and come up with your own logical delimiting syntax to allow you to pull it apart the other side.

Hopefully this is a little help but suspect you'll still be searching around the forums for more info on things, because I've probably left a tonne of gaps in the process. The more I've delved into PA the more I've decoupled the Data handling from PA's own mechanisms and used flow to hand the data to the DB to process. As good as they are, I prefer the flexibility of SQL server in the long term, but this makes PA so much more straightforward and useful from a user front end builder.

johnmarlowe
Level: Powered On

Re: PowerApps Writing back to SQL?

Reading back my post I suspect I may have "over-contributed" a bit!
nirvana_moksh
Level: Powered On

Re: PowerApps Writing back to SQL?

I really appreciate you taking the time out to post this and putting the effort needed to list it all out. This will be my weekend experiment for sure! Thanks again John for being really helpful and awesome with your detail driven posts.