@Component
public class BranchParser implements Parser<Branch> {
    /**
     *  Convert id as string to Branch entity.
     *  In templates use th:value with an id.
     *
     *  Example:
     *  <option th:each="item : ${items}" th:value="${item.getId}"
     *                         th:text="${item}">Value</option>
     */


    private final BranchRepo branchRepo;

    public BranchParser(BranchRepo branchRepo) {
        this.branchRepo = branchRepo;
    }

    @Override
    public Branch parse(String id, Locale locale) throws ParseException {
        Branch branch;
        try {
            branch = this.branchRepo.findById(Integer.parseInt(id)).get();
        } catch (NoSuchElementException | NumberFormatException e) {
            throw new ParseException(0, "Branch not found with id: " + id);
        }
        return branch;
    }
}







package org.springframework.format;

@FunctionalInterface
public interface Parser<T> {

	/**
	 * Parse a text String to produce a T.
	 * @param text the text string
	 * @param locale the current user locale
	 * @return an instance of T
	 * @throws ParseException when a parse exception occurs in a java.text parsing library
	 * @throws IllegalArgumentException when a parse exception occurs
	 */
	T parse(String text, Locale locale) throws ParseException;

}