Building Scalable Applications with Thymeleaf and Spring Boot/

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Custom Editors and Formatters

Custom Editors and Formatters

Learn how custom formatters can be used to directly bind to richer objects.

We'll cover the following...

With Spring MVC and Thymeleaf, we have to convert Java objects from the HTML <input> values. Using String on the FormData objects makes this process trivial.

However, there might be cases where we want to bind to a richer object directly. This can be done by implementing a custom property editor or a custom formatter.

Custom editor

We’ll use PhoneNumber as an example. In AbstractUserFormData, we currently have this:

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@NotBlank
@Pattern(regexp = "[0-9.\\-() x/+]+", groups = ValidationGroupOne.class)
private String phoneNumber;

If we want to use the PhoneNumber class instead of String, we’ll need to create a custom property editor:

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package com.tamingthymeleaf.application.user;
import org.apache.commons.lang3.StringUtils;
import java.beans.PropertyEditorSupport;
public class PhoneNumberPropertyEditor extends PropertyEditorSupport { 
    @Override
    public void setAsText(String text) throws IllegalArgumentException { 
        if (StringUtils.isNotBlank(text)) {
            this.setValue(new PhoneNumber(text)); 
        } else {
            this.setValue(null); 
        }
    }
    @Override
    public String getAsText() { 
        PhoneNumber value = (PhoneNumber) getValue(); 
        return value != null ? value.asString() : ""; 
    }
}

  • Extend from PropertyEditorSupport (Which is a Java SDK class, not a Spring class).

  • Override the setAsText(String text) method. This method must implement the conversion from String to the custom type (PhoneNumber in our example).

  • If the text is not blank, create a PhoneNumber ...