Conditional logic and validation

Introduction to Power Apps

Luise Freese

Azure & Power Platform Architect

Conditional formatting (recap)

Gallery ticket card with a red High priority pill, illustrating conditional Fill coloring driven by an If() formula on Priority.

If(condition, ifTrue, ifFalse), the workhorse
Already seen on gallery row colors
Same shape powers everything in this video

IsBlank(), catching empty fields

IsBlank(value) returns true if the value is empty
Works on any control's value
The validation building block for the rest of the video

Two Title text inputs showing IsBlank() returning true for an empty field and false when the field contains ticket text.

Prevention: DisplayMode

Submit button disabled when Title is empty and enabled once filled, illustrating DisplayMode controlled by an IsBlank() If() formula.

Stop the bad submit before it happens

DisplayMode = If(IsBlank(...), DisplayMode.Disabled, DisplayMode.Edit)

The button grays out until the field is filled

Correction: Notify() after submit

Notify(
    "Save failed: check fields",
    NotificationType.Error
)

Catches what prevention can't: server rules, network errors
Wire OnFailure → Notify() with NotificationType.Error
Use together with prevention, not on its own

Power Apps form with a red error toast, highlighted Title field, and grayed Save button after a failed validation submit.

Visible versus DisplayMode

Side-by-side screens comparing Visible=false removing a button from layout versus DisplayMode=Disabled graying it out in place.

Visible = false → removes from layout, tab order
DisplayMode.Disabled → stays in place, grayed, read-only
DisplayMode.View → for cards inside forms

A concrete example

Approve button: visible to all, Disabled until fields filled
Manager-only section: Visible = isManager
One screen, both rules in action

Dark phone showing a form app with input fields, action cards, and a green submit button.

Server-side vs client-side

Flowchart showing user submit passing through Power Apps client-side checks (IsBlank, DisplayMode) then SharePoint server-side checks (Required column) before saving.

Client-side, in the app: improves UX
Server-side, on SharePoint: protects data integrity

Power Apps formulas are not a security boundary.

What you'll build

Block empty submits with validation
Show error messages when something goes wrong
Show or hide controls based on user role

Dark phone showing a form with input fields and a green submit button representing the finished validation app.

Let's practice!

Introduction to Power Apps