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copied!<p>Here is my generic Criteria filtering method.</p> <p>Properties according to bean conventions have following form <code>foo.bar.name</code>.<br> With Criteria API a tree can be build from a given filtering map and Restrictions can be added. One special case I observed during testing is that filtering on the identifier property does not needs a new subcriteria since this property is already fetched.</p> <pre><code>/** * Creates a detached criteria from the given Type and given map of filters. * * @param type Target type the Criteria is build for. * @param identifierPropertyName If provided (not null) the identifier * property name can be identified for the given type to simplify * the queries if the identifier property is the only property * used on the parent no subqueries are needed. * @param filters * * @see #createTree(Set, String) * @see #addRestrictions(DetachedCriteria, TreeNode) * * @return */ public static DetachedCriteria createDetachedCriteria(final Class<?> type, final String identifierPropertyName, final Map<String, Criterion> filters) { final DetachedCriteria criteria = DetachedCriteria.forClass(type); // add restrictions using tree final TreeNode<Entry<String, Criterion>> rootNode = HibernateUtils2.createTree(filters.entrySet(), identifierPropertyName); final Iterator<TreeNode<Entry<String, Criterion>>> it = rootNode.getChildren().iterator(); while (it.hasNext()) HibernateUtils.addRestrictions(criteria, it.next()); return criteria; } /** * Creates a Tree from the given Set using a fictional root TreeNode. * * @param <T> * * @param filters * @param identifierPropertyName Property name which is merged with its * parent property. Example: <b>user.id</b> is treated as single * property. * @return */ public static <T extends Object> TreeNode<Entry<String, T>> createTree(final Set<Entry<String, T>> filters, final String identifierPropertyName) { final Iterator<Entry<String, Object>> it = filters.iterator(); /* * create key property tree for Entity properties */ final TreeNode<Entry<String, Object>> rootNode = new TreeNode<Entry<String, Object>>( new SimpleEntry<String, Object>("root", null)); while (it.hasNext()) { final Entry<String, Object> entry = it.next(); // foo.bar.name final String key = entry.getKey(); String[] props; /* * check if we have a nested hierarchy */ if (key.contains(".")) { props = key.split("\\."); // check for identifier since identifier property name does not // need new subcriteria if (!StringUtils.isBlank(identifierPropertyName)) { int propsTempLength = props.length - 1; if (props[propsTempLength].equals(identifierPropertyName)) { props = Arrays.copyOf(props, propsTempLength); propsTempLength--; props[propsTempLength] = props[propsTempLength] + "." + identifierPropertyName; } } // check for "this" identifier of beginning, which needs to be // added for projections because of hibernate not recognizing it if (props.length > 1 && props[0].equals("this")) { props[0] = "this." + props[1]; props = ArrayUtils.remove(props, 1); } } else props = new String[] { key }; TreeNode<Entry<String, Object>> currNode = rootNode; // create nested criteria for (int i = 0; i < props.length; i++) { Object valueAdd; // only leaf needs value if (i != props.length - 1) valueAdd = null; else valueAdd = entry.getValue(); final TreeNode<Entry<String, Object>> childTempNode = new TreeNode<Entry<String, Object>>( new SimpleEntry<String, Object>(props[i], valueAdd)); // try to get the real node TreeNode<Entry<String, Object>> childNode = currNode.getChild(childTempNode.getElement()); // check if we already have a unique node if (childNode == null) { childNode = childTempNode; // add new child to set if its a new node currNode.addChild(childNode); } currNode = childNode; } } return rootNode; } /** * Recursively adds the given Restriction's wrapped in the given TreeNode to * the Criteria. * * @param criteria * @param treeNode */ public static void addRestrictions(final DetachedCriteria criteria, final TreeNode<Entry<String, Criterion>> treeNode) { // if we have a leaf simply add restriction if (treeNode.getChildren().size() == 0) criteria.add(treeNode.getElement().getValue()); else { // create new sub Criteria and iterate children's final DetachedCriteria subCriteria = criteria.createCriteria(treeNode.getElement().getKey()); final Iterator<TreeNode<Entry<String, Criterion>>> it = treeNode.getChildren().iterator(); while (it.hasNext()) HibernateUtils.addRestrictions(subCriteria, it.next()); } } /* * Utility classes */ /** * Generic TreeNode implementation with a Set to hold its children to only allow * unique children's. */ public class TreeNode<T> { private final T element; private final Set<TreeNode<T>> childrens; public TreeNode(final T element) { if (element == null) throw new IllegalArgumentException("Element cannot be null"); this.element = element; this.childrens = new HashSet<TreeNode<T>>(); } public void addChildren(final TreeNode<T> children) { this.childrens.add(children); } /** * Retrieves the children which equals the given one. * * @param children * @return If no children equals the given one returns null. */ public TreeNode<T> getChildren(final TreeNode<T> children) { final Iterator<TreeNode<T>> it = this.childrens.iterator(); TreeNode<T> next = null; while (it.hasNext()) { next = it.next(); if (next.equals(children)) return next; } return null; } public T getElement() { return this.element; } public Set<TreeNode<T>> getChildrens() { return this.childrens; } /** * Checks if the element of this instance equals the one of the given * Object. */ @Override public boolean equals(final Object obj) { if (this == obj) return true; if (obj != null && obj instanceof TreeNode) { final TreeNode<?> treeNode = (TreeNode<?>) obj; return this.element.equals(treeNode.element); } else return false; } @Override public int hashCode() { int hash = 1; hash = hash * 17 + this.element.hashCode(); return hash; } } </code></pre> <p>Hope this helps you. Or have a look at the generic dao project you mentioned. I knew about this project and checked it out but never downloaded it.</p> <p>Using this approach a query can be created very simple like following:</p> <pre><code>Map<String, Object> filters = new HashMap<String, Object>(); filters.put("foo.bar.name", Restrictions.like("name", "peter")); filters.put("foo.test.id", Restrictions.eq("id", 2)); List<Class> data = HibernateUtils.createDetachedCriteria(Class, "get identifier from sessionFactory", filters).getExecutableCriteria(session).list(); </code></pre> <p><em>This odd approach to add the property name as the key and into the Restrictions is related to the fact that Restrictions have no getter and setter for property names.</em></p> <p><strong>Custom filtering</strong></p> <p>My real application uses similar code which is not restricted to <code>Criterion</code> class only. For my web tier I created custom filters which are equivalent to Restrictions api but the client does not needs hibernate jar's anymore. </p> <p><strong>Edit</strong></p> <p>Generic filtering across non-entities such as component's and composite-id's is not supported. It can easily be extended with help of <code>ClassMetadata</code> to support them without need for reflection. If code is needed i can provide it.</p>

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