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POCreate Custom Tag that talks to the database
 

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    <p>I want to create a custom tag that talks to the database and retreives records from a table and then displays on a jsp page.</p> <p>I am using spring. and Eclipselink as JPA provider. I wrote a custom class.</p> <pre><code>package com.persistent.testjpa.taghandlers; import java.io.IOException; import java.util.Date; import java.util.List; import javax.servlet.jsp.JspException; import javax.servlet.jsp.JspWriter; import javax.servlet.jsp.tagext.SimpleTagSupport; import org.springframework.beans.factory.annotation.Autowired; import com.persistent.testjpa.dao.MyUserDao; import com.persistent.testjpa.domain.MyAuthorities; public class MyListTagHandler extends SimpleTagSupport { private String tableName; private MyUserDao dao; public String getTableName() { return tableName; } public void setTableName(String tableName) { this.tableName = tableName; } public void doTag() throws JspException, IOException { System.out.println("Indise Do Tag Method"); JspWriter out = getJspContext().getOut(); if (tableName != null) { System.out.println("Table Name : "+getTableName()); out.println("&lt;html&gt;&lt;body&gt;"); out.println("Today's Date is "+ new Date()); out.println("&lt;/body&gt;&lt;/html&gt;"); } else { out.println("&lt;html&gt;&lt;body&gt;"); out.println("Please Enter Table Name"); out.println("&lt;/body&gt;&lt;/html&gt;"); } } @Autowired public void setDao(MyUserDao dao) { this.dao = dao; } public List&lt;MyAuthorities&gt; getList(){ return dao.list(); } } </code></pre> <p>When I try to access the Dao Object The code throws a NullPointer Exception.</p> <p>Can someone tell me what's wrong?</p> <p>Thanks</p>
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    1. COYou can't use Spring autowiring for Tag classes. See http://stackoverflow.com/questions/3924909/how-to-write-tag-in-my-spring-project.
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    2. COHi Thanks for your time. I read the post you referenced. It says we need to set the object in the controller. I want to make a generic tag say myList that has an attribute called tablename. If I pass in an existing table name it should connect to the database and fetch the records and display on the JSP page. Could you provide me some directions on how to achieve this?
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