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

Comments

Popular posts from this blog

A Template for Software Engineering Standards

Software engineering standard template A well-structured standard acts as a blueprint that guides engineers in their daily tasks and long-term goals. Below, I will outline a template for creating a comprehensive software engineering standard. Header The header serves as the document's identifier. It contains the following: Authors : The people who have contributed to the creation of the standard. Created Date : The date when the document was initially created. Version : The version of the standard. It is typically updated with significant changes. Status : The current status of the document, whether it's in draft, in-review, or official. Next Review Date : The date when the standard will be reviewed for relevancy and accuracy. Table of Contents A table of contents provides an overview of what the document contains, making it easier for readers to navigate through the document. Body The body of the standard comprises: Values : The core beliefs that guide the decision-maki...

AngularJS - Build a custom validation directive for using multiple emails in textarea

AngularJS already supports the built-in validation with text input with type email. Something simple likes the following: <input name="input" ng-model="email.text" required="" type="email" /> <span class="error" ng-show="myForm.input.$error.email"> Not valid email!</span> However, I used a text area and I wanted to enter some email addresses that's saparated by a comma (,). I had a short research and it looked like AngualarJS has not supported this functionality so far. Therefore, I needed to build a custom directive that I could add my own validation functions. My validation was done only on client side, so I used the $validators object. Note that, there is the $asyncValidators object which handles asynchronous validation, such as making an $http request to the backend. This is just my implementation on my project. In order to understand that, I supposed you already had experiences with ...

Books Read in 2022

My bookshelf Technical - Operating System: Three Easy Pieces. Andrea Arpaci-Dusseau, Remzi Arpaci-Dusseau. - The Effective Engineer. Edmond Lau. - English Grammar in Use. Raymond Murphy - Mythical Man-Month, The: Essays on Software Engineering. Brooks Jr., Frederick P.  - Peopleware: Productive Projects and Teams (3rd edition). Tom DeMarco, Timothy Lister. - A Philosophy of Software Design. John Ousterhout. - Modern Computer Architecture and Organization: Learn x86, ARM, and RISC-V architectures and the design of smartphones, PCs, and cloud servers. Jim Ledin. Thought Provoking - Đúng Việc. Giản Tư Trung. - A Brief History of Time. Stephen Hawking. - Một đời như kẻ tìm đường. Phan Văn Trường. - Một đời thương thuyết. Phan Văn Trường. - Tinh hoa xử thế - Dám bị ghét. Kishimi Ichiro, Koga Fumitake. - Phép màu để vượt lên chính mình. Nhan Húc Quân. - Scouting for Boys: A Handbook for Instruction in Good Citizenship Through Woodcraft. Robert Baden-Powell. - Thay Đổi Cuộc Sống Với Nhân ...

Think like a Engineering Manager

Off-boarding Members can leave the company for various reasons, and as a manager, it is important to take action. Hoping for the best is not a strategy. In the case of a low-performing member, I can kindly issue an official warning, set clear objectives for improvement, and re-evaluate the results. If there is a conflict between members, I need to be mindful and go beyond the situation to list our expectations with corresponding actions. Finally, if a member has a big chance to grow at another company, I can have an honest discussion with that member about the trade-offs. Balance at Work As an engineering manager, it is important to balance involvement in meetings and getting your hands dirty on some topics. The goal is to become a companion to teams. Here are my two actions to deal with the situation: Dedicate time for important-but-not-urgent tasks and prioritize them daily. Categorize work into four lines including management, project support, OKRs, and self-study. Management Conduc...

Journal: This Month I Learned (2023-April)

I learned that it's important to take breaks and practice self-care to avoid burnout. It's also important to communicate with colleagues and managers about workload and prioritize tasks accordingly. Finally, getting hands-on experience with different aspects of the business can be valuable for personal and professional growth. OKRs review The results of the OKR review should not directly impact performance appraisals. Key Results should be straightforward measurements of Objectives, not just a to-do list. They should also be related to daily work, rather than separate topics. There are two ways to review objectives: "Completion" or "Rating". The status should be balanced among objectives and used to adapt to current efforts. Member reassignment How to find a good fit between business and personnel growth: Salary costs increase year by year. It doesn't make sense to increase customer billing year by year. Burnout counter: Engagement I engage to work close...