Grails hack之改写findAll和find方法
GORM的查询方法很方便(可查看http://www.grails.org/doc/1.2.x/ref/Domain%20Classes/findAll.html)但因为我现在用Db4o，根本就不需要ORM，GORM的finders派不上用场。但是GORM把finders以及validate注入到Domain Classes中的方式对我们很有启发性。
Db4o提供三种查询方式：QBE， NQ和SODA。其中NQ是type-safe的，在编译期可以作语法检查，在运行期可以被Db4o转化成高效的SODA。我不喜欢在Grails中使用NQ，一是因为这让代码看起来不太漂亮，二是无法保证所有的NQ都会被转化成SODA。
利用Groovy的Closure我写了两个方法：findAll和find，最终执行的都是SODA查询。改一改Grails的FindAllPersistentMethod代码：
package com.grs.db4opersistence.metaclass;import com.db4o.ObjectContainer;import com.db4o.query.Query;import com.grs.utils.GroovyDataUtils;import groovy.lang.MissingMethodException;import groovy.lang.Closure;import org.springframework.beans.SimpleTypeConverter;import java.util.Iterator;import java.util.Map;import java.util.regex.Pattern;/** * The "findAll" persistent static method allows searching for instances * * Usages: * (1) 0 arguments: User.findAll() * (2) 1 argument : User.findAll(sortInfoAndExampleMap) : User.findAll(sort:'dateCreated',order:'asc',department:department) * (3) 1 argument : User.findAll(exampleObject) * (4) 2 arguments: User.findAll(sortInfoMap, exampleObject): User.findAll(,userExample) * (5) 1 argument : User.findAll{it.descend('department').constrain(department)} * (6) 2 arguments: User.findAll(sort:'dateCreated',order:'asc'){it.descend('department').constrain(department)} * (7) 2 arguments: User.findAll(sort:'dateCreated',order:'asc',department:department){other complex constraints...} * (8) 3 arguments: User.findAll(sortInfoMap, exampleObject){other complex constraints} * * @author Sam Chen * * Created: Jun 2, 2010 * */public class FindAllPersistentMethod extends AbstractStaticPersistentMethod { public static SimpleTypeConverter converter = new SimpleTypeConverter();public FindAllPersistentMethod(ObjectContainer objectContainer,ClassLoader classLoader) {super(objectContainer, classLoader, Pattern.compile("^findAll$"));}protected Object doInvokeInternal(final Class clazz, String methodName, Closure additionalCriteria, final Object[] arguments) {return doFindAll(clazz, methodName, additionalCriteria, arguments);} protected final Object doFindAll(final Class clazz, String methodName, Closure additionalCriteria, final Object[] arguments) { if (arguments.length == 0) { Query q = getDb4oTemplate().query(); q.constrain(clazz); q.descend("deleted").constrain(false); return q.execute(); } if (arguments.length == 1) { Object arg = arguments; if(clazz.isAssignableFrom(arg.getClass())) { return getDb4oTemplate().queryByExample(arg); } else if(arg instanceof Map) { Query q = getDb4oTemplate().query(); q.constrain(clazz);q.descend("deleted").constrain(false); Map map = (Map) arg; if (map.containsKey("sort") && map.containsKey("order")) { if (map.get("order").equals("desc")) { q.descend((String)map.get("sort")).orderDescending(); } else { q.descend((String)map.get("sort")).orderAscending(); } } for(Iterator<String> it = map.keySet().iterator(); it.hasNext();) { String key = it.next(); if("sort".equals(key) || "order".equals(key)) { continue; } q.descend(key).constrain(map.get(key)); } return q.execute(); } else if(arg instanceof Closure) { Query q = getDb4oTemplate().query(); q.constrain(clazz);q.descend("deleted").constrain(false); ((Closure)arg).call(q); return q.execute(); } else { throw new MissingMethodException(methodName, clazz, arguments); } } if (arguments.length == 2) { Object arg0 = arguments; Object arg1 = arguments; if(!(arg0 instanceof Map)) { throw new MissingMethodException(methodName, clazz, arguments); } Query q = getDb4oTemplate().query(); q.constrain(clazz);q.descend("deleted").constrain(false); Map map = (Map) arg0; if (map.containsKey("sort") && map.containsKey("order")) { if (map.get("order").equals("desc")) { q.descend((String)map.get("sort")).orderDescending(); } else { q.descend((String)map.get("sort")).orderAscending(); } } for (Iterator<String> it = map.keySet().iterator(); it.hasNext();) { String key = it.next(); if("sort".equals(key) || "order".equals(key)) { continue; } q.descend(key).constrain(map.get(key)); } if (arg1 instanceof Closure) { ((Closure) arg1).call(q); } else if (arg1 instanceof Map || clazz.isAssignableFrom(arg1.getClass())) { // extract properties from the domain object... applyConstraintsFromExample(arg1, q); } else { throw new MissingMethodException(methodName, clazz, arguments); } return q.execute(); } if (arguments.length == 3) { Object arg0 = arguments; // sortInfoMap Object arg1 = arguments; // example Object arg2 = arguments; // closure if(!(arg0 instanceof Map) || !(arg1 instanceof Map || clazz.isAssignableFrom(arg1.getClass())) || !(arg2 instanceof Closure)) { throw new MissingMethodException(methodName, clazz, arguments); } Query q = getDb4oTemplate().query(); q.constrain(clazz);q.descend("deleted").constrain(false); Map map = (Map) arg0; if (map.containsKey("sort") && map.containsKey("order")) { if (map.get("order").equals("desc")) { q.descend((String)map.get("sort")).orderDescending(); } else { q.descend((String)map.get("sort")).orderAscending(); } } // extract properties from the domain object... applyConstraintsFromExample(arg1, q); ((Closure)arg2).call(q); return q.execute(); } throw new MissingMethodException(methodName, clazz, arguments); } private void applyConstraintsFromExample(Object o, Query q) { Map properties = (o instanceof Map ? (Map)o : GroovyDataUtils.getProperties(o)); for(Iterator<String> it = properties.keySet().iterator(); it.hasNext();) { String key = it.next(); Object v = properties.get(key); if(v != null) { q.descend(key).constrain(v); } } }}
有了FindAllPersistentMethod方法，FindPersistentMethod就很简单了：
package com.grs.db4opersistence.metaclass;import com.db4o.ObjectContainer;import com.db4o.ObjectSet;import groovy.lang.Closure;import org.springframework.beans.SimpleTypeConverter;import java.util.regex.Pattern;/** * <p> * The "find" persistent static method allows searching for an instance ** @author Sam Chen * Created: Jun 2, 2010 **/public class FindPersistentMethod extends FindAllPersistentMethod { public static SimpleTypeConverter converter = new SimpleTypeConverter();public FindPersistentMethod(ObjectContainer objectContainer, ClassLoader classLoader) {super(objectContainer, classLoader); this.setPattern(Pattern.compile("^find$"));}protected Object doInvokeInternal(final Class clazz, String methodName, Closure additionalCriteria, final Object[] arguments) {ObjectSet os = (ObjectSet)this.doFindAll(clazz, methodName, additionalCriteria, arguments); return os.size() > 0 ? os.get(0) : null;}}
，同时修改它的method signature：
def findAllMethod = new FindAllPersistentMethod(objectContainer, application.classLoader)/** * Usages: * (1) 0 arguments: User.findAll() * (2) 1 argument : User.findAll(sortInfoAndExampleMap) : User.findAll(sort:'dateCreated',order:'asc',department:department) * (3) 1 argument : User.findAll(exampleObject) * (4) 2 arguments: User.findAll(sortInfoMap, exampleObject): User.findAll(,userExample) * (5) 1 argument : User.findAll{it.descend('department').constrain(department)} * (6) 2 arguments: User.findAll(sort:'dateCreated',order:'asc'){it.descend('department').constrain(department)} * (7) 2 arguments: User.findAll(sort:'dateCreated',order:'asc',department:department){other complex constraints...} * (8) 3 arguments: User.findAll(sortInfoMap, exampleObject){other complex constraints} */mc.static.findAll = {-> findAllMethod.invoke(mc.javaClass, "findAll", [] as Object[])}mc.static.findAll = {Object sortMapOrExampleOrClosure-> findAllMethod.invoke(mc.javaClass, "findAll", as Object[])}mc.static.findAll = {Map map, Object eoc -> findAllMethod.invoke(mc.javaClass, "findAll", as Object[])}mc.static.findAll = {Map map, Object example, Closure c-> findAllMethod.invoke(mc.javaClass, "findAll", as Object[])} 再写一点测试代码：
package com.grs.sctmsimport grails.test.*class FindMethodIntegrationTests extends GrailsUnitTestCase { protected void setUp() { super.setUp() for (int i = 0; i < 100; i++) { new User(username:"user#$i", password:"pwd").save() } new User(username:"sam.ds.chen@xxx.com", password:"sam's password").save() } protected void tearDown() { super.tearDown() } void testFindAllWithEmptyArgument() { def users = User.findAll() assertEquals 101, users.size() } void testFindAllWithOneArguments() {// def users = User.findAll(sort:'username',order:'asc')// assertEquals 'sam.ds.chen@xxx.com', users.username def users = User.findAll(sort:'username',order:'asc', password:'pwd') assertEquals 100, users.size() users = User.findAll(new User(password:'pwd')) assertEquals 100, users.size() users = User.findAll{it.descend('password').constrain('pwd')} assertEquals 100, users.size() } void testFindAllWithTwoArguments() { def users = User.findAll(, new User(password:'pwd')) assertEquals 100, users.size() users = User.findAll(sort:'username',order:'asc') { it.descend('username').constrain('user#').like() } assertEquals 100, users.size() users = User.findAll(sort:'username',order:'asc',password:"sam's password") { it.descend('username').constrain('sam.ds.chen@xxx.com') } assertEquals 1, users.size() assertEquals "sam.ds.chen@xxx.com", users.username } void testFindAllWithThreeArguments() { def users = User.findAll(, ) { } assertEquals 1, users.size() assertEquals "sam.ds.chen@xxx.com", users.username users = User.findAll(, new User(password:"sam's password")) { it.descend('password').constrain("sam's password") } assertEquals 1, users.size() assertEquals "sam.ds.chen@xxx.com", users.username }} 测试结果
-------------------------------------------------------Running 2 integration tests...Running test com.grs.sctms.FindMethodIntegrationTests...PASSEDRunning test com.grs.sctms.ValidationIntegrationTests...PASSEDTests Completed in 2485ms ...-------------------------------------------------------Tests passed: 5Tests failed: 0-------------------------------------------------------不过有个小问题： 测试代码中被注释掉的部分
// def users = User.findAll(sort:'username',order:'asc')// assertEquals 'sam.ds.chen@xxx.com', users.username通不过。每次跑的
users.username的值都不一样 - 看来测试环境下排序没生效。而用grails run-app把它跑起来的时候，经debug证实数据是排好序的！怀疑是Grails的bug...
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