Can't set/update nullable reference field to null

[Andrew Swan]

Imagine a reference field that can be null (e.g. a Car can have a Radio or not). There are two problems with the auto-generated views for the Car entity (assuming some Radios have already been added to the database):

• in car/create.jspx, the "Radio" drop-down defaults to blank, but if no Radio is selected, the form fails to submit and shows no error (presumably there is a binding and/or validation problem)
• in car/update.jspx, you can't change a Car from having a Radio to not having a Radio, because the select tag doesn't have a null option even though the Car.radio field can be null in Java.

Here's a test script if you want to try it for yourself:

project --topLevelPackage test
persistence setup --provider HIBERNATE --database HYPERSONIC_IN_MEMORY 
entity --class ~.domain.Car
entity --class ~.domain.Radio
field reference --class ~.domain.Car --fieldName radio --type ~.domain.Radio
controller all --package ~.web

Here's the original view code for the "Radio" field (in both the above views):

<form:select cssStyle="width:250px" id="_radio_id" path="radio">
    <form:options itemValue="id" items="${radios}" />
</form:select>

To fix this, I had to edit both create.jspx and update.jspx to include a null option like this:

<form:select cssStyle="width:250px" id="_radio_id" path="radio">
    <form:option value="" label="(none)"/>
    <form:options itemValue="id" items="${radios}" />
</form:select>

And register a custom PropertyEditor in CarController as follows:

@InitBinder
public void initBinder(final WebDataBinder binder) {
    binder.registerCustomEditor(Radio.class, new PropertyEditorSupport() {
        @Override
        public void setAsText(final String text) {
            if (StringUtils.hasText(text)) {
                setValue(Radio.findRadio(Long.valueOf(text)));
            }
            else {
                setValue(null);
            }
        }
    });
}

It's a pain to do all this work when Roo knows all along that the field can be null. Should I log this as an improvement request (or an enhancement, I never know the difference in JIRA)?

P.S. I'm using Roo 1.0.0.RELEASE (and it still happens in 1.0.1.RELEASE).

[sdyson]

Same problem here. Did you make a feature request?

[Andrew Swan]

Sorry for not mentioning it earlier, but yes I have already logged it as ROO-581. Vote early and vote often!

[maciejb]

Here is how I managed to work around this:
http://maciej.inszy.org/2010/02/18/s...relationships/
it's a generic solution and I think a good one.

Any feedback is greatly appreciated.

[Andrew Swan]

That's a good workaround for Roo 1.0.1 and earlier, especially if you have lots of entity classes that are nullable properties of other entities.

However from Roo 1.0.2 onwards (due out tomorrow), entity finders will gracefully accept a null ID, as per ROO-623. So the only change people will need to make for nullable fields will be to add this line to the relevant select tags:

<form:option value="" label="whatever"/>

(which as you blogged, is also required with your approach)

[aheusingfeld]

Andrew,

I do not see this as a real solution as adding this line to the select tag means modifying the jspx which in turn means I have to disable Roo's management of the according jspx.

There definitely has to be another solution! I'm currently thinking of something like an @After advice which fires after the EntityController.createForm(..) and EntityController.updateForm(..) methods are called contributing an empty element to the relevant lists.
I'll check whether this works...

...if anyone has a better solution I'm all ears!

Cheers
Alex

[mnehrkorn]

I'm working to implement the work-around in this post, but I believe I must have newer versions of the tools because my JSP is using different tags (see below).

Can someone provide some assistance on what this work-around might look like using this newer set of tags?


<form:create id="fc_com_rulereposv4_domain_ICD9List" modelAttribute="iCD9List" path="/icd9lists" render="${empty dependencies}" z="33rQ/5LzxSvLPyzthRVkjx+leqU=">
<field:select field="diagCode" id="c_com_rulereposv4_domain_ICD9List_diagCode" itemValue="id" items="${icd9diagcodes}" path="/icd9diagcodes" z="vAD8YMecyA9YOqEEYJ8yKLOMbmo="/>
<field:select field="procCode" id="c_com_rulereposv4_domain_ICD9List_procCode" itemValue="id" items="${icd9proccodes}" path="/icd9proccodes" z="DK7EgYnsywsFIMMJFE251Pk/XUw="/>
<field:select field="codeGroup" id="c_com_rulereposv4_domain_ICD9List_codeGroup" itemValue="id" items="${codegroups}" path="/codegroups" z="y9Dr2RCF5qETjV18njea9dFe81M="/>
</form:create>

[btlife]

You can either modify the select tag to accept an option to add the please select. Or you can put in the direct tag instead of using the <field:select>
us <form:
instead of

<field:select field="diagCode" id="c_com_rulereposv4_domain_ICD9List_diagCode" itemValue="id" items="${icd9diagcodes}" path="/icd9diagcodes" z="vAD8YMecyA9YOqEEYJ8yKLOMbmo="/>

                  <springform:select id="_diagCode_id"  path="diagCode" >
                 			<springform:option value="" label="--All--" />
                  		<springform:options items="${icd9diagcodes}" itemValue="id" />
                  </springform:select>

you have to add the spring tag library to the tag section at the top of the file

xmlns:springform="http://www.springframework.org/tags/form"

Roo uses the roo generated form.tagx in the tags directory and maps form to

xmlns:form="urn:jsptagdir:/WEB-INF/tags/form"

So you don't want to change this if you are using the other Roo tags. (You probably have other fields that are not drop downs and still want to use the "helper" tags. The helper tags, are wrapping up the spring tag library, but since you are wanting to access the springtag library directly you have to reference it and give it a name that is not currently being used. I picked springform just for fun, you could name it whatever you wanted to.

So a complete listing using your stuff:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<div xmlns:c="http://java.sun.com/jsp/jstl/core" xmlns:field="urn:jsptagdir:/WEB-INF/tags/form/fields" xmlns:form="urn:jsptagdir:/WEB-INF/tags/form" xmlns:springform="http://www.springframework.org/tags/form" xmlns:jsp="http://java.sun.com/JSP/Page" xmlns:spring="http://www.springframework.org/tags" version="2.0">
    <jsp:output omit-xml-declaration="yes"/>
<form:create id="fc_com_rulereposv4_domain_ICD9List" modelAttribute="iCD9List" path="/icd9lists" render="${empty dependencies}" z="33rQ/5LzxSvLPyzthRVkjx+leqU=">
                  <springform:select id="_diagCode_id"  path="diagCode" >
                 			<springform:option value="" label="--All--" />
                  		<springform:options items="${icd9diagcodes}" itemValue="id" />
                  </springform:select>
<field:select field="procCode" id="c_com_rulereposv4_domain_ICD9List_procCode" itemValue="id" items="${icd9proccodes}" path="/icd9proccodes" z="DK7EgYnsywsFIMMJFE251Pk/XUw="/>
<field:select field="codeGroup" id="c_com_rulereposv4_domain_ICD9List_codeGroup" itemValue="id" items="${codegroups}" path="/codegroups" z="y9Dr2RCF5qETjV18njea9dFe81M="/>
</form:create>
</div>

[balteo]

I came across this post and tried to manually implement it as explained by Andrew Swan.
I now systematically get the following exception:

Caused by: javax.servlet.jsp.JspException: java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'command' available as request attribute
	at org.apache.jsp.WEB_002dINF.views.plis.findPlisByMultiField_jspx$Helper.invoke(findPlisByMultiField_jspx.java:440)
	at org.apache.jsp.tag.web.form.find_tagx._jspx_meth_form_005fform_005f0(find_tagx.java:404)
	at org.apache.jsp.tag.web.form.find_tagx.access$1(find_tagx.java:384)
	at org.apache.jsp.tag.web.form.find_tagx$Helper.invoke0(find_tagx.java:484)
	at org.apache.jsp.tag.web.form.find_tagx$Helper.invoke(find_tagx.java:501)
	at org.apache.jsp.tag.web.util.panel_tagx._jspx_meth_c_005fif_005f0(panel_tagx.java:185)
	at org.apache.jsp.tag.web.util.panel_tagx.doTag(panel_tagx.java:131)
	at org.apache.jsp.tag.web.form.find_tagx._jspx_meth_util_005fpanel_005f0(find_tagx.java:351)
	at org.apache.jsp.tag.web.form.find_tagx._jspx_meth_c_005fif_005f0(find_tagx.java:210)
	at org.apache.jsp.tag.web.form.find_tagx.doTag(find_tagx.java:176)
	at org.apache.jsp.WEB_002dINF.views.plis.findPlisByMultiField_jspx._jspService(findPlisByMultiField_jspx.java:89)
	... 113 more
Caused by: java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'command' available as request attribute
	at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:141)
	at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getBindStatus(AbstractDataBoundFormElementTag.java:178)
	at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getPropertyPath(AbstractDataBoundFormElementTag.java:198)
	at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getName(AbstractDataBoundFormElementTag.java:164)
	at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.writeDefaultAttributes(AbstractDataBoundFormElementTag.java:127)
	at org.springframework.web.servlet.tags.form.AbstractHtmlElementTag.writeDefaultAttributes(AbstractHtmlElementTag.java:421)
	at org.springframework.web.servlet.tags.form.SelectTag.writeTagContent(SelectTag.java:199)
	at org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:102)
	at org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:79)
	at org.apache.jsp.WEB_002dINF.views.plis.findPlisByMultiField_jspx$Helper.invoke0(findPlisByMultiField_jspx.java:375)
	at org.apache.jsp.WEB_002dINF.views.plis.findPlisByMultiField_jspx$Helper.invoke(findPlisByMultiField_jspx.java:433)
	... 123 more

Here is my jspx:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<div xmlns:field="urn:jsptagdir:/WEB-INF/tags/form/fields" xmlns:form="urn:jsptagdir:/WEB-INF/tags/form" xmlns:jsp="http://java.sun.com/JSP/Page" xmlns:springform="http://www.springframework.org/tags/form" version="2.0">
    <jsp:directive.page contentType="text/html;charset=UTF-8"/>
    <jsp:output omit-xml-declaration="yes"/>
    <form:find finderName="ByMultiField" id="ff_trc_suivi_domain_Pli" path="/plis" z="user-managed">
        <field:input disableFormBinding="true" field="identifiant" id="f_trc_suivi_domain_Pli_identifiant" max="50" min="1" required="false" z="user-managed"/>
        <field:datetime disableFormBinding="true" field="dateReceptionFrom" dateTimePattern="${pli_datereception_date_format}"  id="f_trc_suivi_domain_Pli_dateReceptionFrom" required="false" z="user-managed"/>
        <field:datetime disableFormBinding="true" field="dateReceptionTo" dateTimePattern="${pli_datereception_date_format}" id="f_trc_suivi_domain_Pli_dateReceptionTo" required="false" z="user-managed"/>
        <field:checkbox disableFormBinding="true" field="paiement" id="f_trc_suivi_domain_Pli_paiement" z="user-managed"/>
        <field:checkbox disableFormBinding="true" field="AR" id="f_trc_suivi_domain_Pli_AR" z="user-managed"/>    
        <field:input disableFormBinding="true" field="numeroAR" id="f_trc_suivi_domain_Pli_numeroAR" max="50" min="1" required="false" z="user-managed"/>
        <field:checkbox disableFormBinding="true" field="FDV" id="f_trc_suivi_domain_Pli_FDV" z="user-managed"/>
        <field:select disableFormBinding="true" field="statut" id="f_trc_suivi_domain_Pli_statut" items="${statutplis}" path="statutplis" required="false" z="user-managed"/>
        <!-- <field:select disableFormBinding="true" field="conteneurNum" id="f_trc_suivi_domain_Pli_conteneurNum" items="${conteneurnums}" itemLabel="identifiant"  itemValue="id" path="conteneurnums" required="false" z="user-managed"/> -->
        <springform:select id="f_trc_suivi_domain_Pli_conteneurNum" path="conteneurnums" >
   			<springform:option value="" label="(blank)" />
       		<springform:options items="${conteneurnums}" itemValue="id" />
        </springform:select>
     </form:find>
</div>

Here is my controller:

package trc.suivi.controller;

import java.beans.PropertyEditorSupport;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;

import org.joda.time.format.DateTimeFormat;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.propertyeditors.CustomDateEditor;
import org.springframework.context.i18n.LocaleContextHolder;
import org.springframework.roo.addon.web.mvc.controller.finder.RooWebFinder;
import org.springframework.roo.addon.web.mvc.controller.scaffold.RooWebScaffold;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

import trc.suivi.domain.ConteneurNum;
import trc.suivi.domain.Pli;
import trc.suivi.domain.StatutPli;
import trc.suivi.repository.PliRepository;

@RequestMapping("/plis")
@Controller
@RooWebScaffold(path = "plis", formBackingObject = Pli.class)
@RooWebFinder
public class PliController {

	@Autowired
	private PliRepository pliRepository;

	@InitBinder
    public void initBinder(WebDataBinder binder) {
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        dateFormat.setLenient(false);
        binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, false));
        binder.registerCustomEditor(ConteneurNum.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(final String text) {
                if (StringUtils.hasText(text)) {
                    setValue(ConteneurNum.findConteneurNum(Long.valueOf(text)));
                }
                else {
                    setValue(null);
                }
            }
        });
    }
	
	@RequestMapping(params = { "find=ByMultiField", "form" }, method = RequestMethod.GET)
	public String findPlisByMultiFieldForm(Model uiModel) {
		populateMultiFieldForm(uiModel);
		return "plis/findPlisByMultiField";
	}

	 @RequestMapping(params = "form", produces = "text/html")
	 public String createForm(Model uiModel) {
	    populateEditForm(uiModel, new Pli());
	    addDateTimeFormatPatterns(uiModel);
	    return "plis/create";
	 }
	
	@RequestMapping(params = "find=ByMultiField", method = RequestMethod.GET)
	public String findPlisByMultiField(
			@RequestParam("identifiant") String identifiant,
			@RequestParam("dateReceptionFrom") Date dateReceptionFrom,
			@RequestParam("dateReceptionTo") Date dateReceptionTo,
			@RequestParam(value="paiement",required=false) Boolean paiement,
			@RequestParam(value="AR",required=false) Boolean ar,
			@RequestParam("numeroAR") String numeroAR,
			@RequestParam(value="FDV", required=false) boolean fdv,
			@RequestParam("conteneurNum") ConteneurNum conteneurNum,
			@RequestParam("statut") StatutPli statut,
			Model uiModel) {
		uiModel.addAttribute("plis", pliRepository.findPlisByMultiField(identifiant, dateReceptionFrom,	dateReceptionTo,  paiement, ar, numeroAR, fdv, conteneurNum, statut));
		return "plis/list";
	}

	void addDateTimeFormatPatterns(Model uiModel) {
        uiModel.addAttribute("pli_datecreation_date_format", "yyyy-MM-dd");
        uiModel.addAttribute("pli_datemodification_date_format", "yyyy-MM-dd");
        uiModel.addAttribute("pli_datereception_date_format", "yyyy-MM-dd");
    }
	
	void populateMultiFieldForm(Model uiModel) {
		uiModel.addAttribute("pli_datereception_date_format", "yyyy-MM-dd");
		uiModel.addAttribute("conteneurnums", ConteneurNum.findAllConteneurNums());
		uiModel.addAttribute("statutplis", Arrays.asList(StatutPli.values()));
	}
}

Can anyone please help?

Regards,

J.

[aehh]

Could you modify the IDT that populates the select list to have a null value option?