Tapestry5: loop, access value in expression

Question

I am trying to use loop component as follows.

<tr t:type="Loop" t:source="summarizer.byAssociationConceptSorted" t:value="entry" >
    <td style="border: 1px solid #EEEEEE; padding: 3px">${page.store.loadConcept(${entry.key}).name}</td>
    <td style="border: 1px solid #EEEEEE; padding: 3px">${entry.value}</td>
</tr>

Here, entry.key is String and entry.value is Long

It generates an exception in Tapestry....."Could not convert 'page.store.loadConcept(${entry.key' into a component parameter binding: Error parsing property expression 'page.store.loadConcept(${entry.key': Unable to parse input at character position 25."

It works fine if I do as follows,

<tr t:type="Loop" t:source="summarizer.byAssociationConceptSorted" t:value="entry" >
    <td style="border: 1px solid #EEEEEE; padding: 3px">${entry.key}</td>
    <td style="border: 1px solid #EEEEEE; padding: 3px">${entry.value}</td>
</tr>

This works fine. Exception is thrown when I try to use entry.key within an expression.

I am also able to use the method loadConcept like this,

<tr t:type="Loop" t:source="summarizer.byAssociationConceptSorted" t:value="entry" >
    <td style="border: 1px solid #EEEEEE; padding: 3px">${page.store.loadConcept('some id').name}</td>
    <td style="border: 1px solid #EEEEEE; padding: 3px">${entry.value}</td>
</tr>

This is means that the problem is not with method or entry.key. The problem is when you try use entry.key within an expression. I am new to Tapestry and trying to learn it, can anyone tell me how to use loop value within some expression?

Answer 1

You can't use expression inside other expression in tapestry. It is always recommended to use separate method in java class for such expressions e.g.:

<tr t:type="Loop" t:source="summarizer.byAssociationConceptSorted" t:value="entry" >
    <td>${entryConcept.name}</td>
    <td>${entry.value}</td>
</tr>

And in java class:

public Concept getEntryConcept() {
    return getPage().getStore().loadConcept(entry.getKey());
}

It is also possible but not recommended to use something like this:

<tr t:type="Loop" t:source="summarizer.byAssociationConceptSorted" t:value="entry" >
    <td>${page.store.loadConcept(entry.key).name}</td>
    <td>${entry.value}</td>
</tr>