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Thymeleaf construct URL with variable

I have the following code setting a variable in my controller:

model.set("type", type);

In the thymeleaf view I want to construct a form with action url:

/mycontroller/{type}

Any ideas how to achieve this? I've read thymeleaf documentation with no luck.


C
Community

As user482745 suggests in the comments (now deleted), the string concatenation I previously suggested

<form th:action="@{/mycontroller/} + ${type}">

will fail in some web contexts.

Thymeleaf uses LinkExpression that resolves the @{..} expression. Internally, this uses HttpServletResponse#encodeURL(String). Its javadoc states

For robust session tracking, all URLs emitted by a servlet should be run through this method. Otherwise, URL rewriting cannot be used with browsers which do not support cookies.

In web applications where the session tracking is done through the URL, that part will be appended to the string emitted for @{..} before the ${..} is appended. You don't want this.

Instead, use path variables as suggested in the documentation

You can also include parameters in the form of path variables similarly to normal parameters but specifying a placeholder inside your URL’s path:

So your example would look like

<form th:action="@{/mycontroller/{path}(path=${type})}"> //adding ending curly brace

C
Community

If You don't want to use string concatenation (proposed by Sotirios), You can use expression preprocessing in URL link:

<form th:action="@{/mycontroller/__${type}__}">

I also think that this is better solution than solution proposed by Sotirios. I have links like th:action="@{/offers/__${offer.id}__/changeStatus}".
This works, but you should be aware that this bypasses the URL encoding of the path variable that Thymeleaf does when using the solution in Sotirios' answer.
u
user482745

You need concatenate string inside @{}.

<form th:action="@{'/mycontroller/' + ${type}}">

@{} is used for URL rewriting. Part of URL rewriting is keeping track of session. First time user request URL, app server adds to url ;jsessionid=somehexvalue and generates cookie with jsessionid. When client sends cookie during next request server knows client supports cookies. If server knows that client support cookies, server will not keep addind jsessionid in URL.

My preferred way is literal substitution with the pipeline syntax (|).

<form th:action="@{|/mycontroller/${type}|}">

Thymeleaf path variable syntax is

<form th:action="@{/mycontroller/{pathParam}(pathParam=${type}}">

Reference: Thymeleaf Standard URL Syntax


I also prefer the literal substitution, as it is clearer and easy to maintain. The thymeleaf syntax is too complex for simple tasks.
Doing string concatenation works for me, but this is very ugly. Why doesn't it just work to write th:href="@{/foo/bar/{obj.property}}"? That does not work for me.
The Thymeleaf version here works nice but it is missing the right parentheses. It should be: <form th:action="@{/mycontroller/{pathParam}(pathParam=${type})}">
e
erhun
Exception evaluating SpringEL expression: "businessId" (login:50)

I have the same problem and solve via string concatination like below.

LoginController.java

@RequestMapping(value = "/login/{businessId}", method = RequestMethod.GET)
    public ModelAndView get(HttpServletRequest request, @PathVariable String businessId) {
        ModelAndView modelAndView = new ModelAndView("login");
        modelAndView.addObject("businessId", businessId);
        return modelAndView;
    }

login.html

            <form role="form" th:action="@{/login} + '/'+ ${businessId}" th:method="post">
                            <fieldset>
                                <div class="form-group">
                                    <input class="form-control" placeholder="E-mail" name="userName"
                                        type="email"></input>
                                </div>
                                <div class="form-group">
                                    <input class="form-control" placeholder="Password"
                                        name="password" type="password" value=""></input>
                                </div>
                                <div class="checkbox">
                                    <label> <input name="remember" type="checkbox"
                                        value="Remember Me"></input>Remember Me
                                    </label>
                                </div>
                                <!-- Change this to a button or input when using this as a form -->
                                <button id="login" class="btn btn-lg btn-success btn-block" type="submit">Login</button>
                            </fieldset>
            </form>