Spring mvc add multiple rows

问题

i need your help as the title says i have a problem inserting multiple rows from a jsp form. The code is from an answer from this site.

Controller

@ModelAttribute("programform")
public ProgramForm populatePojos() {
    // Don't forget to initialize the pojos list or else it won't work
    ProgramForm programform = new ProgramForm();
    List<Programs> programs = new ArrayList<Programs>();
    for(int i=0; i<2; i++) {
        programs.add(new Programs());

    }
    programform.setPrograms(programs);
    return programform;
}




@RequestMapping(value = "/createprog")
public ModelAndView tiles2(@ModelAttribute("programform") ProgramForm  programform,
        BindingResult result) {
    //Map<String, Object> model = new HashMap<String, Object>();
    //model.put("articles",  articleService.listArticles());

    return new ModelAndView("createprogram");
}


@RequestMapping(value = "/saveprogram", method = RequestMethod.POST)
public ModelAndView saveProgram(@ModelAttribute("programform") ProgramForm  programform,
        BindingResult result) {
    for(Programs programs : programform.getPrograms()) {
           System.out.println(programs.getProgram_id());
           articleService.addProgram(programs);
        }

jsp

 <c:url var="saveProgramUrl" value="/articles/saveprogram.html" />
<form:form modelAttribute="programform" method="POST" action="${saveProgramUrl}">
<table>
<tr>
            <th>ProgramId</th>
            <th>Date</th>
            <th>Type</th>
            <th>Start</th>
            <th>End</th>
            <th>Location</th>
            <th>User</th>
            <th>Program Name</th>
</tr>
    <tr> 
                <th><form:input path="programs[0].program_id" /></th>
                 <th> <form:input path="programs[0].date" id="datepick" class="date-pick"/>
        <script type="text/javascript">
            datepickr('datepick', { dateFormat: 'Y-m-d' });
        </script></th>
                <th><form:input path="programs[0].type" /></th>
                <th><form:input path="programs[0].start" /></th>
                <th><form:input path="programs[0].end" /></th>
                <th><form:input path="programs[0].location" /></th>
                <th><form:input path="programs[0].user_id" /></th>
                <th><form:input path="programs[0].program_name" /></th>
    </tr>
 <tr> 
                <th><form:input path="programs[1].program_id" /></th>
                 <th> <form:input path="programs[1].date" id="datepick" class="date-pick"/>
        <script type="text/javascript">
            datepickr('datepick', { dateFormat: 'Y-m-d' });
        </script></th>
                <th><form:input path="programs[1].type" /></th>
                <th><form:input path="programs[1].start" /></th>
                <th><form:input path="programs[1].end" /></th>
                <th><form:input path="programs[1].location" /></th>
                <th><form:input path="programs[1].user_id" /></th>
                <th><form:input path="programs[1].program_name" /></th>
    </tr>
</table>
<br/>
<input type="submit" value="Insert User" />
</form:form>

Program

    package net.roseindia.model;



import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "program")
public class Programs {




    @Id
    @Column(name = "Program_Id")
    private int program_id;
    @Column(name = "Date")
    private String date;
    @Column(name = "Duty_Type")
    private String type;
    @Column(name = "Duty_Start_Time")
    private String start;
    @Column(name = "Duty_End_Time")
    private String end;
    @Column(name = "Location")
    private String location;
    @Column(name = "User_Id")
    private int user_id;
    @Column(name = "Program_Name")
    private String program_name;


    public int getProgram_id() {
        return program_id;
    }


    public void setProgram_id(int program_id) {
        this.program_id = program_id;
    }


    public String getDate() {
        return date;
    }


    public void setDate(String date) {
        this.date = date;
    }


    public String getType() {
        return type;
    }


    public void setType(String type) {
        this.type = type;
    }




    public String getStart() {
        return start;
    }


    public void setStart(String start) {
        this.start = start;
    }


    public String getEnd() {
        return end;
    }


    public void setEnd(String end) {
        this.end = end;
    }


    public String getLocation() {
        return location;
    }


    public void setLocation(String location) {
        this.location = location;
    }


    public int getUser_id() {
        return user_id;
    }


    public void setUser_id(int user_id) {
        this.user_id = user_id;
    }


    public String getProgram_name() {
        return program_name;
    }


    public void setProgram_name(String program_name) {
        this.program_name = program_name;
    }


    public Programs() { 

    }





}

ProgramForm

package net.roseindia.model;

import java.util.List;

public class ProgramForm {



    private List<Programs> programs;

    public List<Programs> getPrograms() {
        return programs;
    }

    public void setPrograms(List<Programs> programs) {
        this.programs = programs;
    }


}

When i push the button to save this to programs nothing inserted in the database, what i am doing wrong?

回答1:

To add multiple rows you need to lazy init your list. Please change your code in the @ModelAttribute("programform") as per following and then try again.

@ModelAttribute("programform") 
public ProgramForm populatePojos() { 
    // Don't forget to initialize the pojos list or else it won't work 
    ProgramForm programform = new ProgramForm(); 
    List<Programs> programs = LazyList.decorate(new ArrayList<Programs>(), FactoryUtils.instantiateFactory(Programs.class));

    for(int i=0; i<2; i++) { 
        programs.add(new Programs()); 

    } 
    programform.setPrograms(programs); 
    return programform; 
}

With having list inilialized as above you can also add more fields run time using javascript and can get those values binded in your list.

After doing this changes if it won't work then you need to do changes in your jsp page. Instead of using the use simple tag but don't forget to specify the same value in name attribute as you have specified in the path attribute here.

Hope this helps you. Cheers.

来源：https://stackoverflow.com/questions/10878748/spring-mvc-add-multiple-rows