如何同时启用Thymeleaf输入字段（th:field）并设置值（th:value）？将${#authentication.name}存入数据库*{pres}位置是否可行？

Hey there! Let's walk through your two Thymeleaf questions and share a working solution I used for a similar scenario (for other devs who might hit this same roadblock):

Here's the key: Thymeleaf's th:field is built to bind directly to a property in your form-backing object (the one you link with th:object). It automatically sets the input's value based on that object's property, so using th:value alongside it can cause conflicts because th:field takes priority.

The cleanest approach is to populate the initial value in your backend controller before passing the object to the view. For example:

// In your Spring controller
@GetMapping("/your-form")
public String showForm(Model model) {
    YourFormDto formDto = new YourFormDto();
    formDto.setTargetField("Your desired initial value"); // Set the value here
    model.addAttribute("formDto", formDto);
    return "your-form-template";
}

Then in your Thymeleaf template:

<form th:object="${formDto}" method="post">
    <input type="text" th:field="*{targetField}" />
</form>

If you must set the value directly in the template (instead of the backend), you can use th:attr to override the value—though this is less ideal for maintainability:

<input type="text" th:field="*{targetField}" th:attr="value='Template-side initial value'" />

Absolutely, this is totally doable! Here are two solid approaches:

Option 1: Backend-driven (Recommended) #

Fetch the authenticated user's name in your controller, assign it to the pres property of your entity/form object, then bind it via th:field in the template. This keeps auth logic in the backend (safer, since frontend values can be tampered with):

// Controller code
import org.springframework.security.core.context.SecurityContextHolder;

@GetMapping("/pres-form")
public String showPresForm(Model model) {
    YourEntity entity = new YourEntity();
    // Grab the authenticated username
    String currentUser = SecurityContextHolder.getContext().getAuthentication().getName();
    entity.setPres(currentUser); // Assign to the `pres` field
    model.addAttribute("entity", entity);
    return "pres-form-template";
}

@PostMapping("/pres-form")
public String submitPresForm(@ModelAttribute YourEntity entity) {
    // Save the entity—your database's `pres` column will get the username
    yourEntityRepository.save(entity);
    return "success-page";
}

Template code:

<form th:object="${entity}" th:action="@{/pres-form}" method="post">
    <!-- Auto-populates with the username from the backend -->
    <input type="text" th:field="*{pres}" readonly /> <!-- Add readonly if users shouldn't edit this -->
    <button type="submit">Save</button>
</form>

Option 2: Template-driven #

If you want to set the value directly in the Thymeleaf template, combine th:field with th:attr to inject the authenticated username:

<form th:object="${entity}" th:action="@{/pres-form}" method="post">
    <input type="text" th:field="*{pres}" th:attr="value=${#authentication.name}" />
    <button type="submit">Save</button>
</form>

Just keep in mind: if your backend entity's pres property already has a value, th:field will use that instead of the template-set value.

My Working Solution for This Exact Scenario #

Since I dealt with this same requirement recently, here's the structure that worked perfectly for me—balancing visibility for users and security for submission:

<form th:object="${document}" th:action="@{/save-document}" method="post">
    <!-- Visible read-only field so users see the username -->
    <input type="text" th:value="${#authentication.name}" readonly class="form-control mb-3" />
    <!-- Hidden field bound to `pres` to pass the value on submission -->
    <input type="hidden" th:field="*{pres}" th:value="${#authentication.name}" />
    <!-- Other form fields -->
    <textarea th:field="*{content}" class="form-control mb-3"></textarea>
    <button type="submit" class="btn btn-primary">Save Document</button>
</form>

Pro tip: Even with the hidden field, I added a validation step in the backend to confirm the submitted pres value matches the authenticated user's name—always good to guard against frontend tampering!

内容的提问来源于stack exchange，提问作者isfa afreen