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possible. Strolch searches are implemented using the <code>StrolchSearch</code> class and
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one of its concrete implementations: <code>ResourceSearch</code>, <code>OrderSearch</code>,
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<code>ActivitySearch</code>.</p><p>A Strolch element always has two identifiers: <code>Type</code> and <code>Id</code>. The type is
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important as it classifies an element. So if a car and a house would be modelled
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in Strolch, then those would both be a <code>Resource</code>, but one of type <code>Car</code>
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and the other of type <code>House</code>. Both would have different parameters. Thus when
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searching for objects, the first thing to do is define the type of object being
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searched.</p><p>The Strolch search API is very expressive and offers multiple ways to perform
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the same search. The search API consists of three components: The search
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classes, the search expressions and the search predicates. The concept was taken
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from the <a href=https://camel.apache.org/>Apache Camel</a> project.</p><p>There are four main search classes:</p><ul><li>RootElementSearch - search for any of Resource, Order or Activity elements</li><li>ResourceSearch - search for Resources</li><li>OrderSearch - search for Orders</li><li>ActivitySearch - search for Activities</li></ul><p>No search is useful without a <code>where</code> clause, which are called search
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expressions. When writing a search, there are multiple ways to add such where
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clauses. Either</p><ul><li>override the <code>define()</code>-method in your sub class and add the where clauses by
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calling the <code>where()</code> method, or</li><li>define special methods on the class e.g. <code>byColor()</code> which also calls the
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<code>where()</code>-method to add a search expression, or</li><li>directly call the <code>where()</code>-method after instantiating a search.</li></ul><p>When extending the class, then the search expressions are available as methods
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on the super class, otherwise you can statically import them from
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<a href=https://github.com/4treesCH/strolch/blob/develop/li.strolch.agent/src/main/java/li/strolch/search/ExpressionsSupport.java>ExpressionsSupport</a>
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.</p><p>And of course a where clause needs operators, which are called search
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predicates. Just as search expressions are available in sub classes, so are
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search predicates and can also be statically imported through
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<a href=https://github.com/4treesCH/strolch/blob/develop/li.strolch.agent/src/main/java/li/strolch/search/PredicatesSupport.java>PredicatesSupport</a>
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.</p><p>Examples of search expressions with search predicates follow:</p><div class=highlight><pre style=color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4><code class=language-java data-lang=java>ResourceSearch search<span style=color:#f92672>=</span><span style=color:#66d9ef>new</span> ResourceSearch<span style=color:#f92672>();</span>
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<span style=color:#75715e>// predicate either as parameter, or chained
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</span><span style=color:#75715e></span>search<span style=color:#f92672>.</span><span style=color:#a6e22e>where</span><span style=color:#f92672>(</span>id<span style=color:#f92672>().</span><span style=color:#a6e22e>isEqualTo</span><span style=color:#f92672>(</span><span style=color:#e6db74>"myId"</span><span style=color:#f92672>));</span>
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search<span style=color:#f92672>.</span><span style=color:#a6e22e>where</span><span style=color:#f92672>(</span>id<span style=color:#f92672>(</span>isEqualTo<span style=color:#f92672>(</span><span style=color:#e6db74>"myId"</span><span style=color:#f92672>)));</span>
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<span style=color:#75715e>// negating
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</span><span style=color:#75715e></span>search<span style=color:#f92672>.</span><span style=color:#a6e22e>where</span><span style=color:#f92672>(</span>id<span style=color:#f92672>(</span>isEqualTo<span style=color:#f92672>(</span><span style=color:#e6db74>"myId"</span><span style=color:#f92672>)).</span><span style=color:#a6e22e>not</span><span style=color:#f92672>());</span>
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search<span style=color:#f92672>.</span><span style=color:#a6e22e>where</span><span style=color:#f92672>(</span>param<span style=color:#f92672>(</span><span style=color:#e6db74>"bagId"</span><span style=color:#f92672>,</span><span style=color:#e6db74>"paramId"</span><span style=color:#f92672>).</span><span style=color:#a6e22e>isIn</span><span style=color:#f92672>(</span>Arrays<span style=color:#f92672>.</span><span style=color:#a6e22e>asList</span><span style=color:#f92672>(</span><span style=color:#e6db74>"red"</span><span style=color:#f92672>,</span><span style=color:#e6db74>"blue"</span><span style=color:#f92672>,</span><span style=color:#e6db74>"green"</span><span style=color:#f92672>)));</span>
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search<span style=color:#f92672>.</span><span style=color:#a6e22e>where</span><span style=color:#f92672>(</span>paramNull<span style=color:#f92672>(</span><span style=color:#e6db74>"bagId"</span><span style=color:#f92672>,</span><span style=color:#e6db74>"paramId"</span><span style=color:#f92672>)));</span>
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<span style=color:#75715e>// boolean operations
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</span><span style=color:#75715e></span>search<span style=color:#f92672>.</span><span style=color:#a6e22e>where</span><span style=color:#f92672>(</span>id<span style=color:#f92672>(</span>isEqualTo<span style=color:#f92672>(</span><span style=color:#e6db74>"myId"</span><span style=color:#f92672>))</span> <span style=color:#75715e>//
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</span><span style=color:#75715e></span> <span style=color:#f92672>.</span><span style=color:#a6e22e>or</span><span style=color:#f92672>(</span>name<span style=color:#f92672>(</span>isEqualTo<span style=color:#f92672>(</span><span style=color:#e6db74>"myName"</span><span style=color:#f92672>))));</span>
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</code></pre></div><p>Note how the predicates can be chained to the search expression, or passed as a
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parameter to the expression.</p><p>In addition to using predefined search search expressions, one can also just
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pass a lambda expression which performs a custom filter:</p><div class=highlight><pre style=color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4><code class=language-java data-lang=java>personSearch<span style=color:#f92672>.</span><span style=color:#a6e22e>where</span><span style=color:#f92672>(</span>person <span style=color:#f92672>-></span> person<span style=color:#f92672>.</span><span style=color:#a6e22e>getName</span><span style=color:#f92672>().</span><span style=color:#a6e22e>length</span><span style=color:#f92672>()</span> <span style=color:#f92672>==</span> 3<span style=color:#f92672>);</span>
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</code></pre></div><p>See
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the <a href=https://github.com/4treesCH/strolch/blob/develop/li.strolch.agent/src/test/java/li/strolch/search/StrolchSearchTest.java>StrolchSearchTest</a>
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for many ways in which you can implement tests.</p><div class="notices tip"><p>Note that strolch searches requires privileges, thus when you
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use a strolch search, add it to the role of the user in <code>PrivilegeRoles.xml</code>:</p></div><div class=highlight><pre style=color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4><code class=language-xml data-lang=xml>
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<span style=color:#f92672><Privilege</span> <span style=color:#a6e22e>name=</span><span style=color:#e6db74>"li.strolch.search.StrolchSearch"</span> <span style=color:#a6e22e>policy=</span><span style=color:#e6db74>"DefaultPrivilege"</span><span style=color:#f92672>></span>
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<span style=color:#f92672><Allow></span>internal
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<span style=color:#f92672></Allow></span> <span style=color:#75715e><!-- internal used for when the search is done in an internal service --></span>
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<span style=color:#f92672><Allow></span>li.strolch.bookshop.search.BookSearch<span style=color:#f92672></Allow></span>
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<span style=color:#f92672></Privilege></span>
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</code></pre></div><footer class=footline></footer></div></div><div id=navigation><a class="nav nav-prev" href=/documentation/services-and-commands/ title="Services and Commands"><i class="fa fa-chevron-left"></i></a><a class="nav nav-next" href=/documentation/queries/ title=Queries style=margin-right:0><i class="fa fa-chevron-right"></i></a></div></section><div style=left:-1000px;overflow:scroll;position:absolute;top:-1000px;border:none;box-sizing:content-box;height:200px;margin:0;padding:0;width:200px><div style=border:none;box-sizing:content-box;height:200px;margin:0;padding:0;width:200px></div></div><script src=/js/clipboard.min.js?1626091328></script><script src=/js/perfect-scrollbar.min.js?1626091328></script><script src=/js/perfect-scrollbar.jquery.min.js?1626091328></script><script src=/js/jquery.sticky.js?1626091328></script><script src=/js/featherlight.min.js?1626091328></script><script src=/js/highlight.pack.js?1626091328></script><script>hljs.initHighlightingOnLoad();</script><script src=/js/modernizr.custom-3.6.0.js?1626091328></script><script src=/js/learn.js?1626091328></script><script src=/js/hugo-learn.js?1626091328></script><script src=/mermaid/mermaid.js?1626091328></script><script>mermaid.initialize({startOnLoad:true});</script></body></html> |