Form Validation

require(["v0.2", "@gui"])

let statusLabel = widget.NewLabel("Fill out the form and click Submit")

// Email entry with validation
let emailEntry = widget.NewEntry()
emailEntry.PlaceHolder = "user@example.com"
emailEntry.SetValidator((text) => {
	if (text == "") {
		return "Email is required"
	}
	if (!text.contains("@")) {
		return "Invalid email format"
	}
	if (!text.contains(".")) {
		return "Invalid email format"
	}
	return nil  // Valid
})

// Age entry with validation
let ageEntry = widget.NewEntry()
ageEntry.PlaceHolder = "18"
ageEntry.SetValidator((text) => {
	if (text == "") {
		return "Age is required"
	}
	let age = int(text)
	if (age < 18) {
		return "Must be 18 or older"
	}
	if (age > 120) {
		return "Invalid age"
	}
	return nil  // Valid
})

// Username entry with validation
let usernameEntry = widget.NewEntry()
usernameEntry.PlaceHolder = "username123"
usernameEntry.SetValidator((text) => {
	if (text == "") {
		return "Username is required"
	}
	if (text.length() < 3) {
		return "Username must be at least 3 characters"
	}
	if (text.length() > 20) {
		return "Username must be less than 20 characters"
	}
	return nil  // Valid
})

// Submit button
let submitBtn = widget.NewButton("Submit", () => {
	// Check if any field has validation errors
	// Fyne will show red borders on invalid fields

	let email = emailEntry.Text
	let age = ageEntry.Text
	let username = usernameEntry.Text

	if (email == "" || age == "" || username == "") {
		statusLabel.SetText("Error: Please fill out all fields")
		return
	}

	// Manual validation check
	if (!email.contains("@") || !email.contains(".")) {
		statusLabel.SetText("Error: Invalid email")
		return
	}

	let ageNum = int(age)
	if (ageNum < 18 || ageNum > 120) {
		statusLabel.SetText("Error: Invalid age")
		return
	}

	if (username.length() < 3) {
		statusLabel.SetText("Error: Username too short")
		return
	}

	// All validations passed
	statusLabel.SetText(sprintf("Success! Welcome %s (age %s, email: %s)", username, age, email))
})
submitBtn.Importance = constants.SuccessImportance

// Clear button
let clearBtn = widget.NewButton("Clear", () => {
	emailEntry.Text = ""
	ageEntry.Text = ""
	usernameEntry.Text = ""
	statusLabel.SetText("Form cleared")
})
clearBtn.Importance = constants.ImportanceLow

let formItems = [
	widget.NewFormItem("Username:", usernameEntry),
	widget.NewFormItem("Email:", emailEntry),
	widget.NewFormItem("Age:", ageEntry),
]

let form = widget.NewForm(formItems)

let buttons = container.NewHBox(submitBtn, clearBtn)

let layout = container.NewVBox(
	widget.NewLabel("Registration Form"),
	form,
	buttons,
	widget.NewSeparator(),
	statusLabel
)

window.SetContent(layout)

cd examples/21-form-validation
go run main.go

fynerisor script.risor