Role based Canvas Apps

The inspiration for this post is this post from Geetha -> https://svaghub.wordpress.com/2018/11/03/role-based-security-in-powerapps-using-spgroups/. The idea is to basically use Flow to check what kind of permission the current user has, so that some functionalities can either be lit up or hidden in the canvas app. In her post, Geetha was using SharePoint user group to get this information. Being from a CRM background, I want this to be retrieved from CDS + I am not a big fan of SharePoint.

Attempt 1: Use DataSourceInfo(‘Users’, DataSourceInfo.CreatePermission), to check if the current user can create Users, which means they are Sys Admin. But, there seems to be a limitation on DataSourceInfo, which means it does not return the correct permissions for CDS entities. It always returns true, which is not correct. So, this attempt was not successful. This would have so much easier if it had worked, as all the logic would be entirely in the canvas app.

Attempt 2: Flow magic. I didn’t want to head this route, but since DataSourceInfo did not work, I had to use Flow to solve the problem. Solution is one of the restricted CDS entities. Only certain roles have access to read this entity OOB. Below are those roles.

Privileges.png

So, I am using this as the flag to show or hide canvas apps controls. Below is my Flow.

Flow.png

There are two parallel branches, one if there is an exception while retrieving Solution records, which means that the user cannot read “Solution” entity and another branch if they have read privilege on “Solution” entity. Depending on which branch the Flow takes, “canread” can be true or false. I can use the result to show or hide controls on the canvas app. The two branches have the appropriate “configure run after” set.

configure run after.png

Branches.png

The clunky bit about this, which I don’t like is that fact that Flow will report that the execution has failed, when Flow takes the “Cannot read Solutions” branch.

Flow result.png

In the programming world, handling an exception appropriately and continuing like nothing happened, is not considered a failure, but it looks like Flow has a different opinion on this.

Potential improvement to the design: Create a new CDS entity called “Canvas App Permission” and create attributes on this entity, to manage which areas in Canvas App should be shown or hidden. Create multiple records of this new entity and assign this to teams or individual users, depending on how you want the permissions to be applied in canvas apps. The Flow can then retrieve this entity, and PowerApps can use this result of the Flow to hide/show areas or functionality.

Hope this is useful. Credit to Geetha for coming up with the original idea.

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Building Spirograph using PowerApps

Over the past few weeks, people have been demonstrating some cool games, built entirely using PowerApps. The reason being, that there was a contest from ThoseDynamicsGuys. If you are interested in finding out about some interesting games from this contest, watch this video from Mr.Dang himself -> https://www.youtube.com/watch?v=0-ZWqs_emQA where he reviews the games.

There were some apps that caught my eye during this period:

  1. Power Flappy by Scott Durow
  2. Power Roulette by Geetha Sivasailam
  3. Coin Dog by Makato Maeda
  4. Air Resistance by Nagao Hiroaki

I was especially fascinated by what Scott and Makato accomplished with the side scrolling nature of the games, how Geetha managed to rotate the roulette as there is no rotate angle property on images and how Nagao managed to calculate the trajectory and resistance of the ball. The first step to learning is to understand how other people do it, so I spend 4-5 days to understand how these apps have been developed.

I then wanted to develop something of my own, using the concepts that I had learnt. Spirograph was the first thing that I thought of. The easiest part was to get the equations to calculate x and y. I had to then learn the basics of starting and stopping a timer, and how to create a sense that the pattern was being “drawn”.

Since image control can render SVG, I decided to try this approach. My first challenge was how do I calculate the x and y on every tick of the timer. So, I decided to follow the approach demonstrated by Brian Dang, that involve checking and un-checking a toggle control.

Every time the toggle is checked, I can increment the iterator variable and calculate x and y for the line to be drawn and the string for the SVG path with all the lines. In SVG you can draw a line, by moving to a location specifying Mxy and then drawing the line using Lxy. Below is the formula in the OnCheckĀ event of the slider

Set(VarI, VarI+1);
UpdateContext({x:
(((RSlider.Value-rSlider.Value) * (Cos(rSlider.Value*VarI/RSlider.Value))) + (aSlider.Value * Cos(VarI*(1-(rSlider.Value/RSlider.Value))))),
y:
(((RSlider.Value-rSlider.Value) * (Sin(rSlider.Value*VarI/RSlider.Value))) - ((aSlider.Value * Sin(VarI*(1-(rSlider.Value/RSlider.Value))))))
});
Collect(Lines, {Row: VarI,
X: x,
Y: y});
Set(PathVar, PathVar & If(PathVar="", "M", "L") & x & "," & y);
true

I can then simply set the SVG path’s d property from the PathVar variable, that has all the line co-ordinates. Below is the value for the Image property of the Image control that renders the Spirograph.

SVG Path.png

Below a video of the app in action. You can play around with the sliders and be fascinated by the patterns that it generates.

Spirograph.gif

Here are some interesting patterns the app generated.

You can download the app from the PowerApps Community Gallery -> https://powerusers.microsoft.com/t5/Community-Apps-Gallery/Spirograph/m-p/175447

References:

SVG Paths – https://developer.mozilla.org/en-US/docs/Web/SVG/Tutorial/Paths#Line_commands

Math behind Spirograph – http://www.mathematische-basteleien.de/spirographs.htm

Improving entity forms using embedded PowerApps

I have been looking into scenarios with PowerApps and Flow that can benefit Dynamics 365 Customer Engagement user experience. One of the scenarios that can add value right away is on the entity forms. PowerApps can be embedded as an IFrame on the normal entity forms, and can be used similar to Dialogs to offload some processing to PowerApps and Flow.

Here is the finished product.

Embed PowerApps in UCI

This works without any JavaScript at all in UCI, with the normal IFrame control on the form. Make sure to tick the option that passes the record id and objecttype code and untick cross site scripting restriction.

IFrame Properties.png

No scripts are needed on the form to embed the PowerApp.

Form Scripts

Once PowerApps is in place, the current form context can be inferred using the “id” parameter that is passed on to the form.

PowerApps Initial

I use a known Guid during the design phase to assist me with the app design process, as the PowerApps calls the Flow during the OnStart event and sets the ProblemDetails variable.

A Flow can be associated to an event, from the Action->Flows area.

Associate Flow.png

When the PowerApps loads, it calls the Flow with the Guid, to retrieve the case details. The Flow that responds to PowerApps with these details on the case: Title, Customer Name, Type of Customer (Account or Contact).

Case Details Flow.png

In this Flow I just use “Respond to PowerApps”action and return the three outputs.

Return to PowerApps.png

I used variables to store the Client, which could be the Account’s name or Contact’s FullName, depending on what is on the case. The client type could be either Account or Contact. Account Details and Contact details are retrieved based on the result of the Client Type branch.

For the second Flow, the user presses the “Check” button which performs some additional checks based on business criteria. For this Flow, I used the “Response” action, which allows me to return JSON results. I stored the cases I am interested in on an array variable.

For each case.png

From the variable, I used Select action to grab only the properties I am interested in.

Select.png

I can then use the “Response” action to return these to PowerApps.

Response.png

One weird thing that I encountered in PowerApps/Flow integration, is that I would simply see the result as “True” from Flow, when I tried to return the return the response straight from the variable.

True Response.png

When I used Parse JSON and then Select to reduce the properties it started working. This can happen when there is something wrong with the schema validation, but I am not sure how this can happen when I copy-paste the JSON response from the previous steps to auto-generate the schema.

One more thing: When the Flow that is associated with the PowerApps changes, just make sure to disassociate and reassociate the Flow. I had issues when I did not do this, due to PowerApps caching the Flow definition.

References;

https://preview.flow.microsoft.com/en-us/blog/howto-upload-return-file/

https://docs.microsoft.com/en-us/powerapps/maker/canvas-apps/get-sessionid