Is fields object from thymeleaf or spring

Question

I saw something as below for form validation using Thymeleaf and Spring boot.

<p th:if="${#fields.hasErrors('datePlanted')}" th:errors="*{datePlanted}">Incorrect date</p>

Now I don't understand: where is this field object coming from? Is this something that Spring prepares? I am lost somewhere here.

Answer 1

Fields.java is a class presented in package org.thymeleaf.spring4.expression.Fields

It's pulled in by thymeleaf-spring4-xxx.jar

#fields.hasErrors is syntax to call method hasErrors() of Fields class.

public boolean hasErrors(final String field) {
    return FieldUtils.hasErrors(this.configuration, this.processingContext, field);
}