Microsoft Power Apps Canvas Apps, Power Fx Formulas, and Controls
View All Tags
You open your app in Power Apps Studio and nothing can be changed. The title says (Read-only), the formula bar says Cannot edit in read-only editor, and a banner explains: This app is read-only because you already have editing control elsewhere. Nobody else is editing; "elsewhere" is another session of yours. Override gets you editing again.
The App checker in Power Apps Studio lists red errors: Missing accessible label, one per control. Your screen looks fine, but people using a screen reader get nothing useful from those controls. The fix is to give each one an AccessibleLabel that says what it is or what it does.
The screen looks perfect on your monitor. Then you preview it on a phone, and the text is cut off: half of a heading disappears under the header, and a sentence ends mid-way. Auto height is on, so the text controls are growing. The problem is the container around them, which has a fixed height and doesn't.
The modern Avatar control is supposed to show a person's initials when they have no photo. With its default settings, for a user without a photo, it showed a grey person silhouette instead. The cause is User().Image, which returns a default picture rather than nothing. One check with Office 365 Users brings the initials back.
Your canvas app calls Office365Users.ManagerV2 and a red banner appears: Office365Users.ManagerV2 failed … Resource 'manager' does not exist or one of its queried reference-property objects are not present. Nothing is broken in your formula. The person simply has no manager in Microsoft 365, and ManagerV2 reports that as an error rather than a blank.
You type a formula with Set, Navigate or Patch into a property, and Power Apps underlines it in red: Behavior function in a non-behavior property. The formula isn't wrong as such; it's in the wrong place. Functions that do something can only run when something happens, such as a button being selected.
The app gets its home in this part: a Power Apps solution that holds the canvas app and three environment variables, which tell the app where its SharePoint data is. By the end, the app is created, connected to both lists and to Microsoft 365 user profiles, and ready for its first screen.
Where you create a canvas app matters. Create it from inside a solution and it belongs to that solution from the start: it can use the solution's environment variables, and it moves with the solution to other environments. This guide does exactly that, and takes a first look around Power Apps Studio.
A canvas app that reads a SharePoint list normally has the site's address and the list built into it. Move the app to another organization and it still points at the old site. Environment variables fix that: the app asks the variables where its data is, and each environment gives them its own values.
A solution is the box you build a Power Apps app in, so that the app and everything it needs can move to another environment together. Every solution belongs to a publisher, and the publisher's prefix ends up in the name of everything you create. Ten minutes spent on both now saves renaming later, which often isn't possible.
