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| <h1 class="content-header header-section1" id="pgui_quickstart_createdatamodel" itemprop="headline">Create a data-model</h1> |
| </div></div><p>In simple cases you can build data-models using |
| <code class="inline-code">java.lang</code> and <code class="inline-code">java.util</code> classes |
| and custom JavaBeans:</p><ul> |
| <li> |
| <p>Use <code class="inline-code">java.lang.String</code> for strings.</p> |
| </li> |
| |
| <li> |
| <p>Use <code class="inline-code">java.lang.Number</code> subclasses for |
| numbers.</p> |
| </li> |
| |
| <li> |
| <p>Use <code class="inline-code">java.lang.Boolean</code> for boolean |
| values.</p> |
| </li> |
| |
| <li> |
| <p>Use <code class="inline-code">java.util.Date</code> and its subclasses for |
| date/time values</p> |
| </li> |
| |
| <li> |
| <p>Use <code class="inline-code">java.util.List</code> or Java arrays for |
| sequences.</p> |
| </li> |
| |
| <li> |
| <p>Use <code class="inline-code">java.util.Map</code> with |
| <code class="inline-code">String</code> keys for hashes.</p> |
| </li> |
| |
| <li> |
| <p>Use your custom bean class for hashes where the items |
| correspond to the bean properties. For example the |
| <code class="inline-code">price</code> property (<code class="inline-code">getPrice()</code>) |
| of <code class="inline-code">product</code> can be get as |
| <code class="inline-code">product.price</code>. (The actions of the beans can be |
| exposed as well; see much later <a href="pgui_misc_beanwrapper.html">here</a>)</p> |
| </li> |
| </ul><p>For example, let's build the data-model of the <a href="dgui_quickstart_basics.html#example.first">first example of the Template Author's |
| Guide</a>. For convenience, here it is again:</p> |
| |
| <div class="code-block role-data-model"> |
| <div class="code-block-label">Data Model</div><pre class="code-block-body">(root) |
| | |
| +- user = "Big Joe" |
| | |
| +- latestProduct |
| | |
| +- url = "products/greenmouse.html" |
| | |
| +- name = "green mouse"</pre> </div> |
| <p>This Java code fragment that builds this data-model:</p> |
| |
| <div class="code-block role-unspecified"> |
| <pre class="code-block-body">// Create the root hash. We use a Map here, but it could be a JavaBean too. |
| Map<String, Object> root = new HashMap<>(); |
| |
| // Put string "user" into the root |
| root.put("user", "Big Joe"); |
| |
| // Create the "latestProduct" hash. We use a JavaBean here, but it could be a Map too. |
| Product latest = new Product(); |
| latest.setUrl("products/greenmouse.html"); |
| latest.setName("green mouse"); |
| // and put it into the root |
| root.put("latestProduct", latest);</pre> </div> |
| <p>As demonstrated above, for hashes (something that stores other |
| named items) you can use either a <code class="inline-code">Map</code> or any kind |
| of public class that has public |
| <code class="inline-code">get<em class="code-color">Xxx</em></code>/<code class="inline-code">is<em class="code-color">Xxx</em></code> |
| methods as prescribed by the JavaBeans specification. Like the above |
| <code class="inline-code">Product</code> class could be something like:</p> |
| |
| <div class="code-block role-unspecified"> |
| <pre class="code-block-body">/** |
| * Product bean; note that it must be a public class! |
| */ |
| public class Product { |
| |
| private String url; |
| private String name; |
| |
| // As per the JavaBeans spec., this defines the "url" bean property |
| // It must be public! |
| public String getUrl() { |
| return url; |
| } |
| |
| public void setUrl(String url) { |
| this.url = url; |
| } |
| |
| // As per the JavaBean spec., this defines the "name" bean property |
| // It must be public! |
| public String getName() { |
| return name; |
| } |
| |
| public void setName(String name) { |
| this.name = name; |
| } |
| |
| }</pre> </div> |
| <p>Regardless if <code class="inline-code">latestProduct</code> is a |
| <code class="inline-code">Map</code> that contains the <code class="inline-code">"name"</code> and |
| <code class="inline-code">"url"</code> keys, or it's a JavaBean as shown above, in |
| the template you can use <code class="inline-code">${latestProduct.name}</code>. The |
| root itself need not be a <code class="inline-code">Map</code> either; it could be |
| an object with <code class="inline-code">getUser()</code> and |
| <code class="inline-code">getLastestProduct()</code> methods too.</p> <div class="callout note"> |
| <strong class="callout-label">Note:</strong> |
| |
| <p>The behavior described here only stands if the value of the |
| <code class="inline-code">object_wrapper</code> configuration setting is something |
| that's used in almost all real world setups anyway. Anything that |
| the <code class="inline-code">ObjectWrapper</code> wraps to be a hash (something |
| that implements the <code class="inline-code">TemplateHashModel</code> interface) |
| can be used as the root, and can be traversed in templates with the |
| dot and <code class="inline-code">[]</code> operators. Something that it doesn't |
| wrap to be a hash can't be used as the root or be traversed like |
| that.</p> |
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