Validating min/max entries in Multivalue fields in Magnolia 5.6+

EntryCountValidatorDefinition.java

package info.magnolia.dev.mgnlui_3527_multifield_validation;

import info.magnolia.ui.form.validator.definition.ConfiguredFieldValidatorDefinition;
import info.magnolia.ui.form.validator.definition.FieldValidatorDefinition;
import info.magnolia.ui.form.validator.factory.AbstractFieldValidatorFactory;
import info.magnolia.ui.form.validator.factory.FieldValidatorFactory;

import java.text.MessageFormat;

import javax.inject.Inject;

import com.vaadin.v7.data.Item;
import com.vaadin.v7.data.Validator;
import com.vaadin.v7.data.validator.AbstractValidator;
import com.vaadin.v7.data.validator.IntegerRangeValidator;

/**
 * Defines a range validator for the count of "property-entries" of a Vaadin {@link Item}.
 *
 * <p>This is especially suited for {@linkplain info.magnolia.ui.form.field.definition.MultiValueFieldDefinition multi-value fields},
 * as they typically hold their entries as a plain {@link com.vaadin.v7.data.util.PropertysetItem PropertysetItem}.
 */
public class EntryCountValidatorDefinition extends ConfiguredFieldValidatorDefinition implements FieldValidatorDefinition {
    private int minValue;
    private int maxValue;

    public int getMinValue() {
        return minValue;
    }

    public void setMinValue(int minValue) {
        this.minValue = minValue;
    }

    public int getMaxValue() {
        return maxValue;
    }

    public void setMaxValue(int maxValue) {
        this.maxValue = maxValue;
    }

    @Override
    public Class<? extends FieldValidatorFactory> getFactoryClass() {
        return EntryCountValidatorFactory.class;
    }

    /**
     * The Magnolia ValidatorFactory.
     */
    private static class EntryCountValidatorFactory extends AbstractFieldValidatorFactory<EntryCountValidatorDefinition> implements FieldValidatorFactory {

        @Inject
        public EntryCountValidatorFactory(EntryCountValidatorDefinition definition) {
            super(definition);
        }

        @Override
        public Validator createValidator() {
            return new EntryCountValidator(getI18nErrorMessage(), definition.getMinValue(), definition.getMaxValue());
        }
    }

    /**
     * And the actual Vaadin Validator.
     */
    private static class EntryCountValidator extends AbstractValidator<Item> {
        private final IntegerRangeValidator delegate;

        public EntryCountValidator(String errorMessage, Integer minValue, Integer maxValue) {
            super(errorMessage);
            MessageFormat messageFormat = new MessageFormat(errorMessage);
            errorMessage = messageFormat.format(new Object[] { minValue, maxValue });
            delegate = new IntegerRangeValidator(errorMessage, minValue, maxValue);
        }

        @Override
        public void validate(Object value) throws InvalidValueException {
            // isValidType ensures that value can safely be cast to TYPE
            if (!isValidType(value)) {
                throw new InvalidValueException(getErrorMessage());
            }
            Item item = (Item) value;
            delegate.validate(item.getItemPropertyIds().size());
        }

        @Override
        public String getErrorMessage() {
            return super.getErrorMessage();
        }

        @Override
        public Class<Item> getType() {
            return Item.class;
        }

        @Override
        protected boolean isValidValue(Item value) {
            throw new IllegalStateException("#isValidValue() should not be used, use #validate() instead.");
        }
    }
}

MGNLUI-3527-multifield-validation.yaml

label: MGNLUI-3527 Multivalue Field with validation
form:
  label: Multivalue Field with validation
  tabs:
    - name: 3527
      label: MGNLUI-3527
      fields:
        - name: ingredients
          class: info.magnolia.ui.form.field.definition.MultiValueFieldDefinition
          transformerClass: info.magnolia.ui.form.field.transformer.multi.DelegatingMultiValueFieldTransformer
          # required: true
          label: Ingredients
          field:
            class: info.magnolia.ui.form.field.definition.TextFieldDefinition
          validators:
            - class: info.magnolia.dev.mgnlui_3527_multifield_validation.EntryCountValidatorDefinition
              minValue: 3
              maxValue: 10
actions:
  commit:
    class: info.magnolia.ui.admincentral.dialog.action.SaveDialogActionDefinition
  cancel:
    class: info.magnolia.ui.admincentral.dialog.action.CancelDialogActionDefinition

mgnlui-3527-multifield-validation_en.properties

samples.MGNLUI-3527-multifield-validation.3527.ingredients.validation.errorMessage=There must be {0} to {1} ingredients.