This event function will fire immediately the the field value changesįunction that transforms field value before saving to form value. This will form the key in the form value Mapĭetermines whether the field widget will accept user input.ĭefines the border, labels, icons, and styles used to decorate the field.Ī FormFieldValidator that will check the validity of value in the FormField In order to create an input field in the form, along with the label, and any applicable validation, there are several attributes that are supported by all types of inputs namely: Attribute FormBuilderTextField - A Material Design text field input.FormBuilderSwitch - On/Off switch field.FormBuilderSlider - For selection of a numerical value on a slider.FormBuilderRangeSlider - Used to select a range from a range of values.FormBuilderRadioGroup - Used to select one value from a list of Radio Widgets.FormBuilderFilterChip - Creates a chip that acts like a checkbox.FormBuilderDropdown - Used to select one value from a list as a Dropdown.FormBuilderDateTimePicker - For Date, Time and DateTime input.FormBuilderDateRangePicker - For selection of a range of dates.

FormBuilderChoiceChip - Creates a chip that acts like a radio button.

FormBuilderCheckboxGroup - List of checkboxes for multiple selection.

FormBuilderCheckbox - Single checkbox field.

React to form fields changes and validations.

Create a form with several type of inputs.

Implement reset, clear or other button into field.

This gives you a convenient way of adding common ready-made input fields instead of creating your own FormBuilderField from scratch. As we added and removed a FormControl, same way you can also add and remove entire FormGroup to FormArray and can have a custom validator to validate that FormGroup.This package helps in creation of data collection forms in Flutter by removing the boilerplate needed to build a form, validate fields, react to changes and collect final user input.Īlso included are common ready-made form input fields for FormBuilder. Then we go through the controls inside the FormArray and get the count for checked ( true) checkboxes. Then if one or more checkboxes are checked we return null which indicates that FormArray is valid. Otherwise, it returns an object having property notSelected set to true, which indicates there is not a single checkbox checked.

Declaration of custom validator function minSelectedCheckboxes(). As we applied this validator to FormArray it will automatically get that FormArray ( demoArray in our case ) and also all its controls.

Adds a custom validator to the FormArray demoArray.

I am assuming that you already have an working Angular project and a component to render your Form. You can also add entirely new FormGroup to the FormArray.įor this article we will use component named DynamicFormComponent which renders our Form. It is not the case that you can only add FormControl to FormArray. This article explains how we can add and remove checkboxes dynamically to and from FormArray and also making a custom validator that checks if at least one checkbox is checked or not.

It might be the case that we want to add FormControl dynamically to FormArray after completion of some operations like the completion of an API call and also want to remove it. Reactive-forms in Angular is very powerful to handle changes in value, check the statuses, and perform validations on a form-field in particular form because of supporting FormGroup, FormControl, and FormArray.īut sometimes it is very difficult to organize the hierarchy and inside the FormGroup and FormArray.

Flutter form builder