# HG changeset patch
# User Raimund Renkert <rrenkert@intevation.de>
# Date 1372338149 -7200
# Node ID bca4bda93a9873bfddff889eeccfc764731b33ab
# Parent  cfa61bb7a86fc73a2c50936462a1bb021176798d
Added builder to have an easier interface for java persistence queries.

diff -r cfa61bb7a86f -r bca4bda93a98 src/main/java/de/intevation/lada/data/QueryBuilder.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/main/java/de/intevation/lada/data/QueryBuilder.java	Thu Jun 27 15:02:29 2013 +0200
@@ -0,0 +1,116 @@
+package de.intevation.lada.data;
+
+import java.util.List;
+
+import javax.persistence.EntityManager;
+import javax.persistence.criteria.CriteriaBuilder;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Expression;
+import javax.persistence.criteria.Order;
+import javax.persistence.criteria.Predicate;
+import javax.persistence.criteria.Root;
+
+public class QueryBuilder<T>
+{
+    private EntityManager manager;
+    private CriteriaBuilder builder;
+    private CriteriaQuery<T> query;
+    private Root<T> root;
+    private Class<T> clazz;
+    private Predicate filter;
+
+    public QueryBuilder(EntityManager manager, Class<T> clazz) {
+        this.manager = manager;
+        this.clazz = clazz;
+        this.builder = this.manager.getCriteriaBuilder();
+        this.query = this.builder.createQuery(this.clazz);
+        this.root = this.query.from(this.clazz);
+    }
+
+    public CriteriaQuery<T> getQuery() {
+        this.query.where(this.filter);
+        return this.query;
+    }
+
+    public QueryBuilder<T> and(String id, String value) {
+        Predicate p = this.builder.equal(this.root.get(id), value);
+        if (this.filter != null) {
+            this.filter = this.builder.and(this.filter, p);
+        }
+        else {
+            this.filter = this.builder.and(p);
+        }
+        return this;
+    }
+
+    public QueryBuilder<T> or(String id, String value) {
+        Predicate p = this.builder.equal(this.root.get(id), value);
+        if (this.filter != null) {
+            this.filter = this.builder.or(this.filter, p);
+        }
+        else {
+            this.filter = this.builder.or(p);
+        }
+        return this;
+    }
+
+    public QueryBuilder<T> and(String id, List<String> values) {
+        for(String v: values) {
+            this.and(id, v);
+        }
+        return this;
+    }
+
+    public QueryBuilder<T> or(String id, List<String> values) {
+        for (String v: values) {
+            this.or(id, v);
+        }
+        return this;
+    }
+
+    public QueryBuilder<T> and(QueryBuilder<T> b) {
+        if (b == null || b.filter == null) {
+            return this;
+        }
+        if (this.filter != null) {
+            this.filter = this.builder.and(this.filter, b.filter);
+        }
+        else {
+            this.filter = this.builder.and(b.filter);
+        }
+        return this;
+    }
+
+    public QueryBuilder<T> or(QueryBuilder<T> b) {
+        if (b == null || b.filter == null) {
+            return this;
+        }
+        if (this.filter != null) {
+            this.filter = this.builder.or(this.filter, b.filter);
+        }
+        else {
+            this.filter = this.builder.or(b.filter);
+        }
+        return this;
+    }
+
+    public void distinct() {
+        this.query.distinct(true);
+    }
+
+    public void orderBy(String id, boolean asc) {
+        if (asc) {
+            this.query.orderBy(this.builder.asc(this.root.get(id)));
+        }
+        else {
+            this.query.orderBy(this.builder.desc(this.root.get(id)));
+        }
+    }
+    
+    public QueryBuilder<T> getEmptyBuilder(){
+        QueryBuilder<T> copy = new QueryBuilder<T>(manager, clazz);
+        copy.builder = this.builder;
+        copy.root = this.root;
+        return copy;
+    }
+}