Form controls

All KVision form controls are available in two variants. The first variant, with class name ending with "Input" (e.g. TextInput), is a basic, fully-functional component ready to be used as a standalone widget. The second variant, with class name without "Input" (e.g. Text), is a wrapper component implementing one of FormControl interfaces and is intended primarily for use with a FormPanel container. This variant can display a label, a validation information and has some additional CSS styling consistent with Bootstrap forms components. From the developer point of view both variants have the same properties and methods (a side of label and rich properties available for second variant only).

The following reference do not differentiate both variants of form controls.

All KVision form controls have the following properties:

• value - allows to get or set the value of the component

• name - defines a name attribute of the HTML input element

• size - allows to set the size of the form control (normal, large or small Bootstrap style)

• disabled - defines whether the form control is disabled

Text fields

i.k.f.text.Text

This component is rendered as a standard HTML text field and is used to get simple, textual data from the user. The type property can be set to any of these values: TEXT, PASSWORD, EMAIL, TEL, COLOR, SEARCH, URL and is bound to the type attribute of the HTML input field. Modern browsers can render such fields with additional elements (e.g. color chooser). Other properties allow you to define a placeholder, a maximum length, autofocus or autocomplete attributes and define if the control should be read-only.

Text(type = TextInputType.URL, label = "WWW") {
    placeholder = "Enter the address"
    maxlength = 255
    autofocus = true
    autocomplete = false
    readonly = false
}

With an additional kvision-imask module loaded and initialized you can use all text input mask options supported by Imask.js library.

text(label = "Phone number") {
    maskOptions = ImaskOptions(pattern = PatternMask("+{7}[phone]", lazy = false, eager = true))
}

i.k.f.text.Password

This component is a direct subclass of i.k.form.text.Text with type property set to TextInputType.PASSWORD.

Password(label = "Password")

i.k.f.text.TextArea

This component is rendered as a standard HTML textarea field and is used to get longer, multi-line textual data from the user. It can be sized with cols and rows properties (mapped to standard HTML attributes).

TextArea(cols = 100, rows = 5, label = "Enter some text")

Alternative way (and preferred nowadays) is to set CSS width and height properties.

TextArea(label = "Enter some text") {
    width = 300.px
    height = 120.px
}

Other properties allow you to define a placeholder, a maximum length, autofocus or hard wrap attributes and define if the control should be read-only.

TextArea(label = "Enter some text") {
    width = 300.px
    height = 120.px
    placeholder = "Enter some text"
    autofocus = true
    wrapHard = true
    readonly = true
}

i.k.f.text.RichText

The kvision-richtext module allows you to use a dedicated form control based on a modern Trix Editor component. It can be used to get rich text from the user. This component renders a text editing field with a toolbar containing basic formatting options (bold, italic, strikethrough, heading, quote, code, link and lists with indentations). The value property contains properly formatted HTML markup. Other properties allow you to define a placeholder and autofocus attribute.

RichText(
    value = "<b>Bold text</b>",
    label = "Rich text field with a placeholder"
) {
    placeholder = "Enter some text"
    autofocus = true
}

i.k.f.text.TomTypeahead

The kvision-tom-select module contains an enhanced text field with support for typeahead (autocomplete) functionality. Both local and remote data sources are supported. To use local data source pass a list of values with the options parameter.

TomTypeahead(
    options = listOf("Alabama", "Alaska", "Arizona", "Arkansas", "California"),
    label = "Select state"
)

To use a remote data source pass a TomSelectCallbacks object with a load callback.

TomTypeahead(
    label = "Select a repository",
    tsCallbacks = TomSelectCallbacks(
        load = { query, callback ->
            restClient.callDynamic("https://api.github.com/search/repositories") {
                data = obj { q = query }
                resultTransform = { it.items }
            }.then { items: dynamic ->
                @Suppress("UnsafeCastFromDynamic")
                callback(items.map { item -> item.name })
            }
        }
    )
)

i.k.f.text.TomTypeaheadRemote

This component is contained in the kvision-tom-select-remote module and is a special version of the Typeahead control, tailored for use with KVision server side interfaces. You can find more information in part 3 of this guide.

Checkboxes and radiobuttons

i.k.f.check.CheckBox

This component can be used to display a checkbox and to get true/false data from the user. The style property can be used to render the checkbox with one of six different styles.

vPanel {
    checkBox(true, label = "Default checkbox") { style = CheckBoxStyle.DEFAULT }
    checkBox(true, label = "Primary checkbox") { style = CheckBoxStyle.PRIMARY }
    checkBox(true, label = "Success checkbox") { style = CheckBoxStyle.SUCCESS }
    checkBox(true, label = "Info checkbox") { style = CheckBoxStyle.INFO }
    checkBox(true, label = "Warning checkbox") { style = CheckBoxStyle.WARNING }
    checkBox(true, label = "Danger checkbox") { style = CheckBoxStyle.DANGER }
}

You can layout your checkboxes horizontally using an inline property.

simplePanel {
    checkBox(true, label = "First") { inline = true }
    checkBox(true, label = "Second") { inline = true }
}

And you can even make the checkbox look like a radiobutton.

checkBox(true, label = "Circled checkbox") { circled = true }

A CheckBox component has a convenient onClick method to easily bind some action to the click event.

checkBox(label = "Click me").onClick {
    println("Clicked")
}

By using indeterminate property you can make the checkbox appear as neither selected nor deselected.

checkBox(label = "Indeterminate checkbox") {
    indeterminate = true
}

i.k.f.check.Radio

This component is similar to the CheckBox component, but it is rendered as a radiobutton. By using the name property, you can group some radiobuttons together, with only one control selected at a time.

vPanel {
    radio(name = "radio", label = "First radiobutton")
    radio(name = "radio", label = "Second radiobutton")
    radio(name = "radio", label = "Third radiobutton")
}

The style property can be used to render the radiobutton with one of six different styles.

vPanel {
    radio(name = "radio", label = "Default radiobutton") { style = RadioStyle.DEFAULT }
    radio(name = "radio", label = "Primary radiobutton") { style = RadioStyle.PRIMARY }
    radio(name = "radio", label = "Success radiobutton") { style = RadioStyle.SUCCESS }
    radio(name = "radio", label = "Info radiobutton") { style = RadioStyle.INFO }
    radio(name = "radio", label = "Warning radiobutton") { style = RadioStyle.WARNING }
    radio(name = "radio", label = "Danger radiobutton") { style = RadioStyle.DANGER }
}

You can layout your radiobuttons horizontally using an inline property.

simplePanel {
    radio(label = "First") { inline = true }
    radio(label = "Second") { inline = true }
}

And you can even make the radiobutton look like a checkbox.

radio(name = "radio", label = "Squared radiobutton") { squared = true }

A Radio component has a convenient onClick method to easily bind some action to the click event.

radio(label = "Click me").onClick {
    println("Clicked")
}

i.k.f.check.RadioGroup

Although it is possible to use basic Radio components to build and manage radiobutton groups (you would have to check which radio in a group is selected), KVision offers a dedicated RadioGroup component, which allows you to treat a group of radiobuttons as a single component returning a String value. It can be initialized with a list of options (key to value pairs) and the selected option can be easily set or get with the value property.

val radioGroup = RadioGroup(
    listOf("option1" to "First option", "option2" to "Second option"),
    inline = true, label = "Radio button group"
)
radioGroup.value = "option1"
println(radioGroup.value)

i.k.f.check.TriStateCheckBox

This component extends the usage of indeterminate property of the standard CheckBox component and allows you to easily use all three states of the checkbox - selected (value = true), deselected (value = false) and indeterminate (value = null).

val tsc = triStateCheckBox(value = true, label = "Tri-state checkbox")
button("Make indeterminate").onClick {
    tsc.value = null
}

Select boxes

i.k.f.select.Select

This is a simple select box component, based on standard HTML select control. It can be used when there is no need for advanced options of the Select component. The SimpleSelect component should be initialized with a list of options (key to values pairs).

Select(
    options = listOf("first" to "First option", "second" to "Second option"),
    label = "Simple select"
)

i.k.f.select.TomSelect

The kvision-tom-select module allows you to use a sophisticated form control based on Tom Select. It's a full-featured component, configurable with plenty of options. It can be used for a simple select picker with a few static options as well as a searchable, dynamic lists pulled over the network. The TomSelect component can be initialized with a list of options (key to values pairs).

TomSelect(
    options = listOf("first" to "First option", "second" to "Second option"),
    label = "Select"
)

You can select many options at the same time with multiple property. You can use tsOptions parameter to provide additional options (e.g. limit the number of selected items). See TomSelect documentation for detailed information about available options.

TomSelect(
    options = listOf("first" to "First option", "second" to "Second option", "third" to "Third option"),
    multiple = true,
    label = "Multiple select",
    tsOptions = TomSelectOptions(maxItems = 2)
)

Other properties allow to define a placeholder, an autofocus attribute and to automatically generate an empty option (to be able to de-select value).

TomSelect(
    options = listOf("first" to "First option", "second" to "Second option"),
    label = "Styled Select"
) {
    placeholder = "Select a value"
    autofocus = true
    emptyOption = true
}

TomSelect component can also work with a remote data source - just pass a TomSelectCallbacks object with a load callback

TomSelect(label = "Select a repository",
    emptyOption = true,
    tsCallbacks = TomSelectCallbacks(
        load = { query, callback ->
            restClient.callDynamic("https://api.github.com/search/repositories") {
                data = obj { q = query }
                resultTransform = { it.items }
            }.then { items: dynamic ->
                @Suppress("UnsafeCastFromDynamic")
                callback(items.map { item ->
                    obj {
                        this.value = item.id
                        this.text = item.name
                        this.subtext = item.owner.login
                    }
                })
            }
        },
        shouldLoad = { it.length >= 3 }
    ),
    tsRenders = TomSelectRenders(option = { item, escape ->
        """
            <div>
                <span class="title">${escape(item.text)}</span>
                <small>(${escape(item.subtext)})</small>
            </div>
        """.trimIndent()
    })
)

i.k.f.select.TomSelectRemote

This component is contained in the kvision-tom-select-remote module and is a special version of TomSelect control, tailored for use with KVision server side interfaces. You can find more information in part 3 of this guide.

Numeric

i.k.f.number.Spinner

This is a simple integer field component, based on standard HTML input control. You can set min and max values (default - no limits) and set the step value (default 1).

Spinner(label = "Number 10 - 20", 
    min = 10, 
    max = 20, 
    step = 2)

i.k.f.number.Range

This component can be used to allow a user to select numeric value with a slider. You need to configure min (default 0), max (default 100) and step (default 1) attributes.

Range(label = "Range field 10 - 20", min = 10, max = 20)

Note: the actual appearance of the control may depend on your browser.

i.k.f.number.Numeric

This component can be used for fixed precision decimal numbers (e.g. currency). You need do set a number of decimal digits (default 2) and the component will automatically format the number. You can set min and max values (default - no limits). You can also specify a decimal digit character or just use the auto-detected default.

Numeric(label = "Product price", min = 0)

i.k.f.number.ImaskNumeric

With kvision-imask module you can use the advanced numeric component, which allows you to work with all decimal numbers (with or without fixed number of decimal digits) and fully controls the characters entered by the user. By setting decimals property to a larger value (up to 15) you can support inputs with different number of decimal digits.

ImaskNumeric(label = "Enter number", decimals = 15)

If you want to support fixed decimals, set padFractionalZeros = true - the component will automatically format the number.

ImaskNumeric(label = "Product price", min = 0, padFractionalZeros = true)

You can also use decimals and thousands separator chars (both are automatically detected from the current locale).

Note: All numeric components are based on JavaScript Number type, which is double-precision 64-bit binary format IEEE 754. The range and precision of represented numbers is limited. To prevent rounding errors KVision limits the range of supported numbers to about 14 digits.

Others

i.k.f.time.DateTime

Both kvision-datetime module allows you to use a sophisticated form control based on Tempus-dominus library. Is It's a full-featured component, configurable with plenty of options. It can be used to display date and/or time picker, based on the date format specified with Fecha library formatting tokens. The default format is "YYYY-MM-DD HH:mm", which means the control will display date and time picker.

DateTime(format = "YYYY-MM-DD", label = "Date field") {
    placeholder = "Enter date"
}

DateTime(format = "HH:mm", label = "Time field") {
    placeholder = "Enter time"
}

DateTime(label = "Date and time field") {
    placeholder = "Enter date and time"
}

Other properties allow you to set days of the week that should be disabled, visibility of "Clear", "Close" and "Today" buttons and also the increment used to build the hour view (default - 5 minutes).

DateTime(label = "Date and time field") {
    placeholder = "Enter date and time"
    daysOfWeekDisabled = arrayOf(0, 6) // Saturday, Sunday
    showClear = false
    showClose = false
    showTodayButton = false
    stepping = 30
}

You can also use minDate, maxDate, enabledDates and disabledDates properties to control which dates the user is allowed to choose.

i.k.f.upload.BootstrapUpload

The kvision-bootstrap-upload module allows you to use a form component based on Bootstrap fileinput, which allows the user to select and upload files. It can be used as a standard file input element, with files being sent as a multi-part form submission or as an AJAX submission and it can be also used as a client-side file selection tool to be used with FileReader API available in modern browsers. The Upload component has a lot of options to customize its appearance and functionality - see API documentation for more details.

Standard HTML form submission

You can use the Upload component to upload files to the server with standard multi-part form action. You should create the FormPanel container with additional parameters (FormMethod.POST, FormEnctype.MULTIPART). In this mode you will be able to upload only one file at a time (unless you add more Upload controls). You should also add a button with type SUBMIT.

formPanel<Form>(FormMethod.POST, "/upload", FormEnctype.MULTIPART) {
    add(Form::text, Text(label = "Text", name = "text_field"))
    add(Form::upload, BootstrapUpload(label = "Upload file").apply {
        name = "file_field"
    })
    hPanel {
        button("Submit", type = ButtonType.SUBMIT)
    }
}

AJAX upload

To use this mode you have to create a server endpoint responsible for processing an AJAX request and returning the correctly formatted response (at least an empty JSON object {}). More information can be found on this Bootstrap fileinput page. On the client side you can use all available options including multiple file uploads. There is no need to add any form parameters or submit buttons.

formPanel<Form> {
    add(Form::text, Text(label = "Text"))
    add(Form::upload, BootstrapUpload("/ajax-upload", label = "Upload file").apply {
        multiple = true
        explorerTheme = true
        dropZoneEnabled = false
        allowedFileTypes = setOf("image")
    })
}

In this mode you have to handle your uploaded files and the rest of your form data separately. Alternatively you can use uploadExtraData property and add your form data directly to your AJAX request.

formPanel<Form> {
    add(Form::text, Text(label = "Text"))
    add(Form::upload, BootstrapUpload("/ajax-upload", label = "Upload file").apply {
        uploadExtraData = { _, _ -> [e-mail]() }
    })
}

Client side file handling

Modern browsers support FileReader API and allow you to work with files entirely on the client side. The FormPanel<K> class has a suspending getDataWithFileContent extension function, which is using Kotlin coroutines to read the content of all uploaded files as BASE64 dataURL strings. It makes it very easy to use such content in other KVision components (e.g. images or any HTML formatted text).

formPanel<Form> {
    add(Form::text, Text(label = "Caption"))
    add(Form::upload, BootstrapUpload("/", label = "Image").apply {
        showUpload = false
        showCancel = false
        explorerTheme = true
        allowedFileTypes = setOf("image")
    })
    hPanel {
        button("Use form data").onClickLaunch {
            val fdata = [e-mail]()
            val firstImage = fdata.upload?.firstOrNull()?.content
            if (firstImage != null) {
                Alert.show(fdata.text, "<img src=\"$firstImage\">", rich = true)
            }
        }
    }
}

Note: You need to set uploadUrl parameter (e.g. to "/" value), even though it's not directly used in this mode.