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Posted to users@tapestry.apache.org by jaques robert <mo...@yahoo.fr> on 2010/03/24 13:20:43 UTC

Could not find a coercion (T5)

Hi,

I've got a simple T5 file with the following loop :
<<
<form t:type="form" t:id="inputs">
    <t:Loop t:source="processTypes" t:value="processType">    
            <div id="div_processus_${processType.processTypeDN}" style="display: block">
                    <a href="#" onclick="javascript:foldOrUnfold('div_processus_${processType.processTypeDN}')">${processType.processType} (${processType.processTypeDN})</a>    
                    <t:Loop t:source="processType.documentTypes" t:value="documentType">
                        <div id="div_documenttype_${documentType.documentTypeDn}" style="display: block">
                                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                                <a href="#" onclick="javascript:foldOrUnfold('div_documenttype_${documentType.documentTypeDn}')">
                                    ${documentType.documentType} (${documentType.documentTypeDn})
                                </a>                            
                                ...
                        ..
                    </t:Loop>
            ...
    </t:Loop>
    <t:submit t:id="save" value="Sauvegarder"/>
    <t:submit t:id="retour" value="Retour"/>
</form>
>>

When accessing this page with a simple get via the browser it works well however when I click on the submit button included in this page, I've got the following error of Type coercion.
<<
org.apache.tapestry5.ioc.internal.util.TapestryException
Could not find a coercion from type java.lang.String to type com.wizard.data.model.ExportProcessType.
 Available coercions: Double --> Float, Float --> Double, Long --> Boolean, Long --> Byte, Long --> Double, Long --> Integer, 
 Long --> Short, Number --> Long, Object --> Object[], Object --> String, Object --> java.util.List, Object[] --> java.util.List, String --> Boolean, 
 String --> Double, String --> Long, String --> java.io.File, String --> java.math.BigDecimal, String --> java.math.BigInteger, String --> java.text.DateFormat, 
 String --> java.util.regex.Pattern, String --> org.apache.tapestry5.Renderable, String --> org.apache.tapestry5.SelectModel, String --> org.apache.tapestry5.corelib.LoopFormState, 
 String --> org.apache.tapestry5.corelib.data.BlankOption, String --> org.apache.tapestry5.corelib.data.GridPagerPosition, String --> org.apache.tapestry5.corelib.data.InsertPosition, 
 String --> org.apache.tapestry5.ioc.Resource, String --> org.apache.tapestry5.ioc.util.TimeInterval, boolean[] --> java.util.List, byte[] --> java.util.List,
 char[] --> java.util.List, double[] --> java.util.List, float[] --> java.util.List, int[] --> java.util.List, java.math.BigDecimal --> Double, java.util.Collection --> Boolean,
 java.util.Collection --> Object[], java.util.Collection --> org.apache.tapestry5.grid.GridDataSource, java.util.List --> org.apache.tapestry5.SelectModel, java.util.Map --> org.apache.tapestry5.SelectModel,
 long[] --> java.util.List, null --> Boolean, null --> org.apache.tapestry5.grid.GridDataSource, org.apache.tapestry5.ComponentResources --> org.apache.tapestry5.PropertyOverrides, 
 org.apache.tapestry5.PrimaryKeyEncoder --> org.apache.tapestry5.ValueEncoder, org.apache.tapestry5.Renderable --> org.apache.tapestry5.Block, 
 org.apache.tapestry5.Renderable --> org.apache.tapestry5.runtime.RenderCommand, org.apache.tapestry5.ioc.util.TimeInterval --> Long, 
 org.apache.tapestry5.runtime.ComponentResourcesAware --> org.apache.tapestry5.ComponentResources, short[] --> java.util.List.
>>

I cannot understand why this error occurs. Have you got any pointers which could guide me toward this error ?

Regards,
Mondes_engloutis.

Re: Could not find a coercion (T5)

Posted by Michael Gentry <mg...@masslight.net>.

Here is one from our code (I made no attempt to map it to yours, but
hopefully it'll give you an idea):

	@Property
	private final ValueEncoder<SurveyAnswer> answerEncoder = new
ValueEncoder<SurveyAnswer>() {
		@Override
		public String toClient(SurveyAnswer answer) {
			int in = question.getAnswers().indexOf(answer);
			return String.valueOf(in);
		}

		@Override
		public SurveyAnswer toValue(String str) {
			if(StringUtils.isNotBlank(str)){
				return question.getAnswers().get(Integer.parseInt(str));
			}else{
				return null;
			}
		}
	};

This one basically uses the integer index into a list to be passed
in/out of the ValueEncoder.

mrg


On Wed, Mar 24, 2010 at 9:16 AM, jaques robert
<mo...@yahoo.fr> wrote:
> Thanks a lot.
>
> <<
> If you're editing ExportProcessType instances, implement a ValueEncoder
> for that type and use pass it to the encoder parameter of Loop.
> If
> you're not, try formState="none" in the Loop.
>>>
>
> Have you got some samples about using ValueEncoder ?
>
> Regards,
> Mondes_engloutis.
>
> --- En date de : Mer 24.3.10, Thiago H. de Paula Figueiredo <th...@gmail.com> a écrit :
>
> De: Thiago H. de Paula Figueiredo <th...@gmail.com>
> Objet: Re: Could not find a coercion (T5)
> À: "Tapestry users" <us...@tapestry.apache.org>
> Date: Mercredi 24 mars 2010, 13h40
>
> On Wed, 24 Mar 2010 09:20:43 -0300, jaques robert <mo...@yahoo.fr> wrote:
>
>> Hi,
>
> Hi!
>
>> org.apache.tapestry5.ioc.internal.util.TapestryException
>> Could not find a coercion from type java.lang.String to type com.wizard.data.model.ExportProcessType.
>
> If you're editing ExportProcessType instances, implement a ValueEncoder for that type and use pass it to the encoder parameter of Loop.
> If you're not, try formState="none" in the Loop.
>
> --Thiago H. de Paula Figueiredo
> Independent Java, Apache Tapestry 5 and Hibernate consultant, developer, and instructor
> Owner, software architect and developer, Ars Machina Tecnologia da Informação Ltda.
> http://www.arsmachina.com.br
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tapestry.apache.org
> For additional commands, e-mail: users-help@tapestry.apache.org
>
>
>
>
>

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Re: Could not find a coercion (T5)

Posted by "Thiago H. de Paula Figueiredo" <th...@gmail.com>.

On Wed, 24 Mar 2010 10:56:00 -0300, jaques robert  
<mo...@yahoo.fr> wrote:

> So it works for the display, however it
> seems that it isn't sufficiant for update ... Why ?

Because Tapestry needs to keep information about the looped objects so  
they can be correctly updated when the form is submitted.

-- 
Thiago H. de Paula Figueiredo
Independent Java, Apache Tapestry 5 and Hibernate consultant, developer,  
and instructor
Owner, software architect and developer, Ars Machina Tecnologia da  
Informação Ltda.
http://www.arsmachina.com.br

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Re: Could not find a coercion (T5)

Posted by jaques robert <mo...@yahoo.fr>.

I don't understand the need of use of coercion inside loop. Indeed 
in my loop I define :
<<
 <t:Loop t:source="processTypes"
 t:value="processType" formState="none">    
            <div 
id="div_processus_${processType.processTypeDN}" style="display: 
block">
                    <a href="#" 
onclick="javascript:foldOrUnfold('div_processus_${processType.processTypeDN}')">${processType.processType}
 (${processType.processTypeDN})</a>    

<t:Loop t:source="processType.documentTypes" t:value="documentType"
 formState="none">
                        <div 
id="div_documenttype_${documentType.documentTypeDn}" style="display: 
block">
>>

So it works for the display, however it 
seems that it isn't sufficiant for update ... Why ? The samples from jumpstart don't make use of such kind of valueencoder

Regards,
Mondes_engloutis.

--- En date de : Mer 24.3.10, Thiago H. de Paula Figueiredo <th...@gmail.com> a écrit :

De: Thiago H. de Paula Figueiredo <th...@gmail.com>
Objet: Re: Could not find a coercion (T5)
À: "Tapestry users" <us...@tapestry.apache.org>
Date: Mercredi 24 mars 2010, 14h22

On Wed, 24 Mar 2010 10:16:10 -0300, jaques robert <mo...@yahoo.fr> wrote:

> Have you got some samples about using ValueEncoder ?

It's quite easy. toClient() should return the id of the received object. toValue() should return the object that has a given id. This last method is usually implemented using a database lookup (using a DAO or otherwise). Just do what the Javadoc tells you to do.

--Thiago H. de Paula Figueiredo
Independent Java, Apache Tapestry 5 and Hibernate consultant, developer, and instructor
Owner, software architect and developer, Ars Machina Tecnologia da Informação Ltda.
http://www.arsmachina.com.br

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Re: Could not find a coercion (T5)

Posted by "Thiago H. de Paula Figueiredo" <th...@gmail.com>.

On Wed, 24 Mar 2010 10:16:10 -0300, jaques robert  
<mo...@yahoo.fr> wrote:

> Have you got some samples about using ValueEncoder ?

It's quite easy. toClient() should return the id of the received object.  
toValue() should return the object that has a given id. This last method  
is usually implemented using a database lookup (using a DAO or otherwise).  
Just do what the Javadoc tells you to do.

-- 
Thiago H. de Paula Figueiredo
Independent Java, Apache Tapestry 5 and Hibernate consultant, developer,  
and instructor
Owner, software architect and developer, Ars Machina Tecnologia da  
Informação Ltda.
http://www.arsmachina.com.br

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Re: Could not find a coercion (T5)

Posted by jaques robert <mo...@yahoo.fr>.

Thanks a lot.

<<
If you're editing ExportProcessType instances, implement a ValueEncoder 
for that type and use pass it to the encoder parameter of Loop.
If 
you're not, try formState="none" in the Loop.
>>

Have you got some samples about using ValueEncoder ? 

Regards,
Mondes_engloutis.

--- En date de : Mer 24.3.10, Thiago H. de Paula Figueiredo <th...@gmail.com> a écrit :

De: Thiago H. de Paula Figueiredo <th...@gmail.com>
Objet: Re: Could not find a coercion (T5)
À: "Tapestry users" <us...@tapestry.apache.org>
Date: Mercredi 24 mars 2010, 13h40

On Wed, 24 Mar 2010 09:20:43 -0300, jaques robert <mo...@yahoo.fr> wrote:

> Hi,

Hi!

> org.apache.tapestry5.ioc.internal.util.TapestryException
> Could not find a coercion from type java.lang.String to type com.wizard.data.model.ExportProcessType.

If you're editing ExportProcessType instances, implement a ValueEncoder for that type and use pass it to the encoder parameter of Loop.
If you're not, try formState="none" in the Loop.

--Thiago H. de Paula Figueiredo
Independent Java, Apache Tapestry 5 and Hibernate consultant, developer, and instructor
Owner, software architect and developer, Ars Machina Tecnologia da Informação Ltda.
http://www.arsmachina.com.br

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Re: Could not find a coercion (T5)

Posted by "Thiago H. de Paula Figueiredo" <th...@gmail.com>.

On Wed, 24 Mar 2010 09:20:43 -0300, jaques robert  
<mo...@yahoo.fr> wrote:

> Hi,

Hi!

> org.apache.tapestry5.ioc.internal.util.TapestryException
> Could not find a coercion from type java.lang.String to type  
> com.wizard.data.model.ExportProcessType.

If you're editing ExportProcessType instances, implement a ValueEncoder  
for that type and use pass it to the encoder parameter of Loop.
If you're not, try formState="none" in the Loop.

-- 
Thiago H. de Paula Figueiredo
Independent Java, Apache Tapestry 5 and Hibernate consultant, developer,  
and instructor
Owner, software architect and developer, Ars Machina Tecnologia da  
Informação Ltda.
http://www.arsmachina.com.br

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