Databases
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    <p>The method expression is not evaluated during the request of displaying the form (the encode step as the book is talking about), but during the request of processing the form submit (the decode step as the book is talking about). The inputs and actions of the datatable row are determined on basis of the table's row index. During processing of the form submit, JSF re-iterates over the data model in order to find the submitted values and the invoked actions.</p> <p>So, if the <code>&lt;h:dataTable value&gt;</code> is tied to a request scoped bean and thus the data model is reinitialized on a per-request basis, then you'll risk the <code>#{item}</code> to <em>actually</em> reference the item at the wrong index during the processing the form submit, because between the requests of displaying the form and submitting the form, the DB might have retrieved a new item, or have removed another item, which would potentially move the desired item to a different index.</p> <p>To avoid this, the bean needs to be placed in the view scope so that exactly the same datamodel which is initialized in (post)constructor of the initial request will be preserved across postbacks without the need to reinitialize it during the beginning of every single request and thus potentially containing different items or in a different order. The influence is bigger if loading of the datamodel is tied to a specific request parameter under full control of the enduser like a search query.</p> <p>An alternative, which is actually a bad one in this particular non-idempotent "Delete this item" case, but a good one for the idempotent "Edit this item" case, would be to use a GET link instead. The desired item is immediately rendered as query string parameter of the <code>&lt;a&gt;</code> element.</p> <pre><code>&lt;h:link value="Edit" outcome="edit"&gt; &lt;f:param name="id" value="#{item.id}" /&gt; &lt;/h:link&gt; </code></pre>
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    1. COo.k. so if I understand you correctly, 1. the book should read "between the rendering of the table and the decoding of the **postback**" and 2. using request scope should just plain be avoided when using this technique?
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    2. COThat's correct.
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Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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