DATACMNS-669 - Introduced QuerydslBindingsFactory.

QuerydslBindingsFactory creates a completely build up and customized QuerydslBindings instance for a given QuerydslBinderCustomizer type and domain type.

This basically involves creating or obtaining an instance of the customizer with the following algorithm:

1. If an explicit customizer type is given and no BeanFactory is configured, we'll simply instantiate the configured type. This allows simple customizer implementations with a no-arg constructor.
2. If a BeanFactory is configured and a customizer type configured, we're trying to locate a bean of that type in the BeanFactory, falling back to creating an instance of the customizer through the BeanFactory if no existing bean definition can be found. This allows unique customizer bean definitions or complex prototype scoped customizer beans created on the fly.
3. If no customizer type is configured, we check whether the the repository of the domain type implements QuerydslBinderCustomizer and use it if so.

The extraction of that functionality allows that algorithm being used by Spring Data REST, although only step 3 is currently used there as no explicit customizer can currently be configured with Spring Data REST.

src/test/java/org/springframework/data/querydsl/binding/QuerydslBindingsFactoryUnitTests.java

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+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.querydsl.binding;
+
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
+
+import java.util.Collections;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.springframework.beans.factory.config.AutowireCapableBeanFactory;
+import org.springframework.data.mapping.PropertyPath;
+import org.springframework.data.querydsl.QUser;
+import org.springframework.data.querydsl.SimpleEntityPathResolver;
+import org.springframework.data.querydsl.User;
+import org.springframework.data.repository.support.Repositories;
+import org.springframework.data.util.ClassTypeInformation;
+import org.springframework.data.util.TypeInformation;
+import org.springframework.data.web.querydsl.QuerydslPredicate;
+import org.springframework.test.util.ReflectionTestUtils;
+import org.springframework.web.servlet.ModelAndView;
+
+import com.mysema.query.types.Path;
+import com.mysema.query.types.Predicate;
+import com.mysema.query.types.path.StringPath;
+
+/**
+ * Unit tests for {@link QuerydslBindingsFactory}.
+ * 
+ * @author Oliver Gierke
+ * @soundtrack Miles Davis - All Blues (Kind of Blue)
+ */
+public class QuerydslBindingsFactoryUnitTests {
+
+	static final TypeInformation<?> USER_TYPE = ClassTypeInformation.from(User.class);
+
+	public @Rule ExpectedException exception = ExpectedException.none();
+
+	QuerydslBindingsFactory factory;
+
+	@Before
+	public void setUp() {
+		this.factory = new QuerydslBindingsFactory(SimpleEntityPathResolver.INSTANCE);
+	}
+
+	/**
+	 * @see DATACMNS-669
+	 */
+	@Test
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	public void createBindingsShouldHonorQuerydslBinderCustomizerHookWhenPresent() {
+
+		Repositories repositories = mock(Repositories.class);
+
+		when(repositories.hasRepositoryFor(User.class)).thenReturn(true);
+		when(repositories.getRepositoryFor(User.class)).thenReturn(new SampleRepo());
+
+		QuerydslBindingsFactory factory = new QuerydslBindingsFactory(SimpleEntityPathResolver.INSTANCE);
+		ReflectionTestUtils.setField(factory, "repositories", repositories);
+
+		QuerydslBindings bindings = factory.createBindingsFor(null, USER_TYPE);
+		MultiValueBinding<Path<Object>, Object> binding = bindings
+				.getBindingForPath(PropertyPath.from("firstname", User.class));
+
+		assertThat(binding.bind((Path) QUser.user.firstname, Collections.singleton("rand")),
+				is((Predicate) QUser.user.firstname.contains("rand")));
+	}
+
+	/**
+	 * @see DATACMNS-669
+	 */
+	@Test
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	public void shouldReuseExistingQuerydslBinderCustomizer() {
+
+		AutowireCapableBeanFactory beanFactory = mock(AutowireCapableBeanFactory.class);
+		when(beanFactory.getBean(SpecificBinding.class)).thenReturn(new SpecificBinding());
+
+		QuerydslBindingsFactory factory = new QuerydslBindingsFactory(SimpleEntityPathResolver.INSTANCE);
+		ReflectionTestUtils.setField(factory, "beanFactory", beanFactory);
+
+		QuerydslBindings bindings = factory.createBindingsFor(SpecificBinding.class, USER_TYPE);
+		MultiValueBinding<Path<Object>, Object> binding = bindings
+				.getBindingForPath(PropertyPath.from("firstname", User.class));
+
+		assertThat(binding.bind((Path) QUser.user.firstname, Collections.singleton("rand")),
+				is((Predicate) QUser.user.firstname.eq("RAND")));
+	}
+
+	/**
+	 * @see DATACMNS-669
+	 */
+	@Test
+	public void rejectsPredicateResolutionIfDomainTypeCantBeAutoDetected() {
+
+		exception.expect(IllegalStateException.class);
+		exception.expectMessage(QuerydslPredicate.class.getSimpleName());
+		exception.expectMessage("root");
+
+		factory.createBindingsFor(null, ClassTypeInformation.from(ModelAndView.class));
+	}
+
+	static class SpecificBinding implements QuerydslBinderCustomizer<QUser> {
+
+		public void customize(QuerydslBindings bindings, QUser user) {
+
+			bindings.bind(user.firstname).first(new SingleValueBinding<StringPath, String>() {
+
+				@Override
+				public Predicate bind(StringPath path, String value) {
+					return path.eq(value.toUpperCase());
+				}
+			});
+
+			bindings.bind(user.lastname).first(new SingleValueBinding<StringPath, String>() {
+
+				@Override
+				public Predicate bind(StringPath path, String value) {
+					return path.toLowerCase().eq(value);
+				}
+			});
+
+			bindings.excluding(user.address);
+		}
+	}
+
+	public static class SampleRepo implements QuerydslBinderCustomizer<QUser> {
+
+		@Override
+		public void customize(QuerydslBindings bindings, QUser user) {
+
+			bindings.bind(QUser.user.firstname).first(new SingleValueBinding<StringPath, String>() {
+
+				@Override
+				public Predicate bind(StringPath path, String value) {
+					return path.contains(value);
+				}
+			});
+		}
+	}
+}