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This guide shows you how to validate required fields in Joyfill forms.

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How It Works

Joyfill automatically validates required fields based on:
  • Field requirement: Fields marked as required = true
  • Field visibility: Hidden fields are always considered valid (even if required)
  • Field values: Required fields must have non-empty values to be valid

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Document-Level Validation

Validate all fields in your document: 
val editor = rememberDocumentEditor(json)

// Validate entire document
val validity = editor.validate()

when (validity) {
    is FieldsValid -> {
        // All required fields have values
        println("All fields are valid!")
    }
    is FieldsInvalid -> {
        // Handle validation errors
        println("Some fields are invalid")
    }
}

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Handling Invalid Fields

When some required fields are empty: 
when (val validity = editor.validate()) {
    is FieldsInvalid -> {
        // Access valid fields directly
        validity.validFields.forEach { field ->
            println("${field.component.title} is valid")
        }
        
        // Access invalid fields directly
        validity.invalidFields.forEach { field ->
            println("${field.component.title} is invalid")
            field.messages.forEach { message ->
                println("Error: $message")
            }
        }
    }
}

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Individual Field Validation

Validate specific fields: 
// Get a field editor
val nameField = editor.fields.text("Full Name")

// Validate the field
val fieldValidity = nameField?.validate()

when (fieldValidity) {
    is ComponentValid -> {
        println("Field is valid")
    }
    is ComponentInvalid -> {
        println("Field is invalid:")
        fieldValidity.messages.forEach { message ->
            println("- $message")
        }
    }
}

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Validation Messages

Required field validation provides standard error messages: 
when (val validity = editor.validate()) {
    is FieldsInvalid -> {
        validity.invalidFields.forEach { field ->
            // Standard format: "Component [title] is required"
            println(field.messages.first()) // "Component Full Name is required"
        }
    }
}

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Checking Field Requirements

Check if a field is required: 
val nameField = editor.fields.text("Full Name")
val isRequired = nameField?.component?.required == true

if (isRequired) {
    println("This field is required")
}

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Validation Rules

Field TypeConditionValid?
RequiredHas non-empty valueYes
RequiredEmpty or nullNo
RequiredHiddenYes (always)
OptionalAny valueYes (always)

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Key Points

  • Required fields are automatically validated based on the required property
  • Hidden fields are always valid, even if marked as required
  • Validation errors use the format: “Component [title] is required”
  • Call editor.validate() anytime to get current validation status
  • Document validation checks all visible required fields at once