Skip to main content

Attribute 'for' of label component with id xxxx is not defined


I got the warning in the log file when I have used the tag <h:outputLabel> without attribute "for" in xhtml file. It was really polluting my server log files.

The logged information actually makes sense anyway! We could find an answer as the following:

"Having h:outputLabel without a "for" attribute is meaningless. If you are not attaching the label, you should be using h:outputText instead of h:outputLabel."

However, these solutions are not possible just for my situation. Instead of using h:outputText for only displaying text, my team has used h:outputLabel too many places. We were nearly in our release time (next day) so it is quite risky and takes much efforts if we try to correct it. Because the style (with CSS) is already done with h:ouputLabel. The alternative by adding attribute "for" the existing h:outputLabel is not reasonable either. I really need to find another solution.

Fortunately, I came across a way if I change to use p:outputLabel, the warning won't be logged! What?

I was just curious to know why; so then I decided to delve into the implementation of outputLabel of both Primefaces and Myfaces source code (at grepcode.com). I found the reason is:

In Myfaces (1.2.2), we can easily to find the line of code below in method "encodeBegin" in class "HtmlLabelRenderer". It is executed whether the attribute "for" is null.

log.warn("Attribute 'for' of label component with id " 
+ uiComponent.getClientId(facesContext)+" is not defined");

However, Primefaces (5.2) does not. In class "OutputLabelRenderer", it uses the default implementation of method "encodeBegin" from superclass without logging. Ahh! The method "encodeBegin" is just a hook!

Okay! The reason is clear. I saw that the only difference of HTML rendering between h:outputLabel and p:outputLabel is as below:

1. <h:ouputLabel> will be rendered  to become <label>
2. <p:outputLabel> will be rendered to become <label class="ui-outputlabel">

It should be an acceptable approach to fix the issue in my case. I just do a little bit more with style and I can achieve my goal without spending much efforts for testing whole the application again. Yeah!

Something like this:

1. XHTML

<h:panelGroup layout="block" styleClass="child-add-ons-container">

    <ul>

        <li>

            <h:panelGroup layout="block" styleClass="type-of-check">

                <p:outputLabel value="bonity"></p:outputLabel>

            </h:panelGroup>

        <li>

        ....

    <ul>

</h:panelGroup>

2. CSS: just make sure the style of p:outputLabel is the same with current style of h:outputLabel, for example:
.add-ons-compliance-check .type-of-check label.ui-outputlabel {

    font-style: normal; /*style of tag label in our app*/

    color: inherit;  /*style of tag label in our app*/

    font: inherit;  /*style of tag label in our app*/

}

References
[1]. http://stackoverflow.com/questions/12744264/attribute-for-of-label-error
[2]. http://docs.oracle.com/javaee/5/javaserverfaces/1.2/docs/tlddocs/h/outputLabel.html
[3]. http://grokbase.com/t/myfaces/users/143vdzqp11/how-to-disable-label-warnings
[4]. http://grepcode.com/file/repo1.maven.org/maven2/org.primefaces/primefaces/5.2/org/primefaces/component/outputlabel/OutputLabelRenderer.java?av=f
[5]. http://grepcode.com/file/repository.springsource.com/org.apache.myfaces/com.springsource.org.apache.myfaces/1.2.2/org/apache/myfaces/renderkit/html/HtmlLabelRenderer.java?av=f
Labels:

Comments

Post a Comment

Popular posts from this blog

How to apply Lean - Kanban for your business

This is the topic of Scrum Breakfast meetup this time, speaker: Ms. Phuong Bui - Technical Project Manager of YOOSE Pte. Ltd. http://www.meetup.com/Scrum-Breakfast-Vietnam-Agile-and-Scrum-Meetup/events/230313727/ Lean comes from Lean manufacturing is a method that focuses on elimination of wastes. In other words, this is a set of principles for archiving the quality, speed and customer alignment. The first time I knew about the term "Lean" is  from the book Software Craftsmanship . Sandro recommends if we want to transform our pet projects into a real business, we should get familiar with Lean Startup concepts. In this talk, Ms. Phuong pointed out some major wastes includes information (ex: unclear requirements), processes (ex: waiting), physical environment and people. Knowing what the problems should be the best way to eliminate them. The difference between  Single item flow and Batch processing is the second main point; and it is the Lean's idea. Batch pr...
Post a Comment
Read more

[Snippet] CSS - Child element overlap parent

I searched from somewhere and found that a lot of people says a basic concept for implementing this feature looks like below: HTML code: <div id="parent">  <div id="child">  </div> </div> And, CSS: #parent{   position: relative;   overflow:hidden; } #child{   position: absolute;   top: -1;   right: -1px; } However, I had a lot of grand-parents in my case and the above code didn't work. Therefore, I needed an alternative. I presumed that my app uses Boostrap and AngularJs, maybe some CSS from them affects mine. I didn't know exactly the problem, but I believed when all CSS is loaded into my browser, I could completely handle it. www.tom-collinson.com I tried to create an example to investigated this problem by Fiddle . Accidentally, I just changed: position: parent; to position: static; for one of parents -> the problem is solved. Look at my code: <div class="modal-body dn-placeholder-parent-positi...
Post a Comment
Read more

Software Craftsmanship by Sandro Mancuso

Source: http://www.goodreads.com/book/show/18054154-software-craftsmanship My first time to know about the term "Software Craftsmanship" is from Agile Tour Vietnam 2015. I finally read this book written by Sandro Mancuso who I met at this event. Software Craftsmanship is a metaphor for software development: software as a craft and developers as blacksmiths. In other words, Software Craftsmanship is about professionalism in software development. The Software Craftsmanship manifesto: Not only working software, but also well-crafted software : regardless how old the application is, developers can understand it easily; high an reliable test coverage, clear and simple design, business language well expressed in the code. Not only responding to change, but also steadily adding value : constantly improving the structure of the code, keeping it clean, extendable, testable, and easy to maintain; always leave the code cleaner than we found it. Not only individuals and int...
Post a Comment
Read more

The HelloWorld example of JSF 2.2 with Myfaces

I just did by myself create a very simple app "HelloWorld" of JSF 2.2 with a concrete implementation Myfaces that we can use it later on for our further JSF trying out. I attached the source code link at the end part. Just follow these steps below: 1. Create a Maven project in Eclipse (Kepler) with a simple Java web application archetype "maven-archetype-webapp". Maven should be the best choice for managing the dependencies , so far. JSF is a web framework that is the reason why I chose the mentioned archetype for my example. 2. Import dependencies for JSF implementation - Myfaces (v2.2.10) into file pom.xml . The following code that is easy to find from  http://mvnrepository.com/  with key words "myfaces". <dependency> <groupId>org.apache.myfaces.core</groupId> <artifactId>myfaces-api</artifactId> <version>2.2.10</version> </dependency> <dependency> <groupId>org.apache.myfaces.core<...
Post a Comment
Read more

Selenium - Use Explicit Waits for checking elements quickly disappear like loading icon

I have a table that is displayed a list of competence groups. When I click on a competence group, it will display a table that contains a lot of criteria belong to the competence group. Each times I click on a competence group, a "loading" icon is displayed while waiting for all criteria is fully displayed. <div id="loading" style="display: none;"> <div></div> <div></div> I tried to write a Selenium test to make sure this behavior is covered. I saw that the loading icon element is always available on DOM tree because I just used Jquery to handle its displaying. Beside that, the loading icon is appeared dynamically and quickly disappear afterwards. It is hard to checking the visibility on GUI of loading icon. By normal way that I frequently used, the code looks like: public boolean isLoadingIconDisplayed() { List<WebElement> loadingIcons = driver.findElements(By.id("loading")); if(!loadingIcons.isE...
Post a Comment
Read more