Examples of how to use the Caldera Forms filter caldera_forms_field_attributes to modify Caldera Forms input elements. See: https://calderaforms.com/doc/caldera_forms_field_attributes/

caldera_forms_field_attributes-add-attr.php

<?php
add_filter( 'caldera_forms_field_attributes', function( $attrs, $field, $form ){
	if( 'button' === Caldera_Forms_Field_Util::get_type( $field, $form ) ){
		$attrs[ 'data-form-id' ] = $form[ 'ID' ];
	}

	return $attrs;

}, 20, 3 );

caldera_forms_field_attributes-add-class.php

<?php
add_filter( 'caldera_forms_field_attributes', function( $attrs, $field, $form ){
	if( 'text' === Caldera_Forms_Field_Util::get_type( $field, $form ) ){
		$attrs[ 'class' ] .= ' my-special-class';
	}

	return $attrs;

}, 20, 3 );

caldera_forms_field_attributes-number-max.php

<?php
/**
 * Set all Caldera Forms number fields' max value to 75
 */
add_filter( 'caldera_forms_field_attributes', function( $attrs, $field, $form ){
	if( 'number' === Caldera_Forms_Field_Util::get_type( $field, $form ) ){
		$attrs[ 'max' ] = 75;
	}

	return $attrs;

}, 20, 3 );

/**
 * Set the Caldera Forms number field with the ID of fld_456's  max value to 75
 */
add_filter( 'caldera_forms_field_attributes', function( $attrs, $field, $form ){
	if( 'fld_456' === $field[ 'ID' ] && 'number' === Caldera_Forms_Field_Util::get_type( $field, $form ) ){
		$attrs[ 'max' ] = 75;
	}

	return $attrs;

}, 20, 3 );

/**
 * Set all Caldera Forms number fields that are in the form with the ID cf_12324's max value to 75
 */
add_filter( 'caldera_forms_field_attributes', function( $attrs, $field, $form ){
	if( 'cf_12324' === $form[ 'ID' ] && 'number' === Caldera_Forms_Field_Util::get_type( $field, $form ) ){
		$attrs[ 'max' ] = 75;
	}

	return $attrs;

}, 20, 3 );

caldera_forms_field_attributes-para-max.php

<?php
/**
 * Set all Caldera Forms paragraph fields' maxlength to 75
 */
add_filter( 'caldera_forms_field_attributes', function( $attrs, $field, $form ){
	if( 'paragraph' === Caldera_Forms_Field_Util::get_type( $field, $form ) ){
		$attrs[ 'maxlength' ] = 75;
	}

	return $attrs;

}, 20, 3 );

/**
 * Set the Caldera Forms paragraph field with the ID of fld_456's maxlength to 75
 */
add_filter( 'caldera_forms_field_attributes', function( $attrs, $field, $form ){
	if( 'fld_456' === $field[ 'ID' ] && 'paragraph' === Caldera_Forms_Field_Util::get_type( $field, $form ) ){
		$attrs[ 'maxlength' ] = 75;
	}

	return $attrs;

}, 20, 3 );

/**
 * Set all Caldera Forms paragraph fields that are in the form with the ID cf_12324's maxlength to 75
 */
add_filter( 'caldera_forms_field_attributes', function( $attrs, $field, $form ){
	if( 'cf_12324' === $form[ 'ID' ] && 'paragraph' === Caldera_Forms_Field_Util::get_type( $field, $form ) ){
		$attrs[ 'maxlength' ] = 75;
	}

	return $attrs;

}, 20, 3 );

disable-date-picker-days-of-the-week.php

<?php
//Disable saturday and sunday as options for date picker fields
//see: http://bootstrap-datepicker.readthedocs.io/en/latest/options.html?highlight=disable#daysofweekdisabled
add_filter( 'caldera_forms_field_attributes', function( $attrs, $field, $form ){
	if( 'date_picker' === Caldera_Forms_Field_Util::get_type( $field, $form ) ){
		$attrs[ 'data-date-days-of-week-disabled' ] = '06';
	}

	return $attrs;

}, 20, 3 );