Thymeleaf bind a String field to a select box - string

Question

#GetMapping("add")
public String addPart(Model model)
{
model.addAttribute("suppliers", this.partService.getSupplierNames());
model.addAttribute("part", new AddPartViewModel());
return "parts/parts-add";
}
This is my class
public class AddPartViewModel
{
private String name;
private double price;
private int quantity;
private String supplierName;
//PUBLIC GETERS AND SETTERS AND AN EMPTY CONSTRUCTOR
}
Thymeleaf syntax
<div class="form-group">
<label for="supplierName">Example select</label>
<select class="form-control" id="supplierName">
<option th:each="name : ${suppliers}" th:text="${name}" th:field="*{supplierName}"></option>
</select>
</div>
This is the only place where i get error on. The rest of the fragment works correctly, even if just remove the th:field tag the List<String> suppliers parces it self correctly in to the select box. Not i tried to put the th:field in the <select> tag as well, i.e
<select class="form-control" id="supplierName" th:field="*{supplierName}">
but still i get an error during parcing

Answer 1

th:field reffers to a form-backing bean's field, so make sure you've provided the proper bean in a <form> tag (using th:object attribute).
Regarding select: th:field should be provided in a <select> tag, like you've attempted to do. But you should provide also the proper th:value attribute in a <option> tag, so that any value could be assigned to the field.
Your form containing the problematic select should look like this:
<form th:object="${part}">
<div class="form-group">
<label for="supplierName">Example select</label>
<select class="form-control" th:field="*{supplierName}">
<option th:each="name : ${suppliers}" th:value="${name}" th:text="${name}"></option>
</select>
</div>
<!-- the rest of form's inputs and buttons -->
</form>