Merge pull request #10666 from tkvw/feature-databinding-initializer

Created BindInitializer annotation

Author: graemerocher

grails-databinding/src/main/groovy/grails/databinding/BindInitializer.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2013 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 grails.databinding;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * This annotation may be applied to a a field to
+ * customize initialization of object properties in the data binding process.
+ *
+ * When the annotation is applied to a field, the value assigned to the
+ * annotation should be a Closure which accepts 1 parameter.  The 
+ * parameter is the object that data binding is being applied to.  
+ * The value returned by the Closure will be bound to the field.  The
+ * following code demonstrates using this technique to bind a contact
+ * to user with the same account as the user.
+ *
+<pre>
+class Contact{
+  Account account
+  String firstName
+} 
+class User {
+    &#064;BindInitializer({
+        obj -> new Contact(account:obj.account)
+    })
+    Contact contact
+    Account account
+}
+</pre>
+ 
+ *
+ * @since 3.2.11
+ * @see BindingHelper
+ * @see DataBindingSource
+ */
+@Retention(RetentionPolicy.RUNTIME)
+public @interface BindInitializer {
+    Class<?> value();
+}

grails-databinding/src/main/groovy/grails/databinding/SimpleDataBinder.groovy

@@ -18,26 +18,22 @@ package grails.databinding
 import grails.databinding.converters.FormattedValueConverter
 import grails.databinding.converters.ValueConverter
 import grails.databinding.events.DataBindingListener
+import grails.databinding.initializers.ValueInitializer
 import groovy.transform.CompileStatic
 import groovy.transform.TypeCheckingMode
 import groovy.util.slurpersupport.GPathResult
+import org.grails.databinding.ClosureValueConverter
+import org.grails.databinding.ClosureValueInitializer
+import org.grails.databinding.IndexedPropertyReferenceDescriptor
+import org.grails.databinding.converters.*
+import org.grails.databinding.errors.SimpleBindingError
+import org.grails.databinding.xml.GPathResultMap
 
 import java.lang.annotation.Annotation
 import java.lang.reflect.Array
 import java.lang.reflect.Field
 import java.lang.reflect.ParameterizedType
 
-import grails.databinding.BindUsing
-import org.grails.databinding.ClosureValueConverter
-import org.grails.databinding.IndexedPropertyReferenceDescriptor
-import org.grails.databinding.converters.ConversionService
-import org.grails.databinding.converters.FormattedDateValueConverter
-import org.grails.databinding.converters.StructuredCalendarBindingEditor
-import org.grails.databinding.converters.StructuredDateBindingEditor
-import org.grails.databinding.converters.StructuredSqlDateBindingEditor
-import org.grails.databinding.errors.SimpleBindingError
-import org.grails.databinding.xml.GPathResultMap
-
 /**
  * A data binder that will bind nested Maps to an object.
  *
@@ -713,9 +709,51 @@ class SimpleDataBinder implements DataBinder {
     }
 
     protected initializeProperty(obj, String propName, Class propertyType, DataBindingSource source) {
-        obj[propName] = propertyType.newInstance()
+        def initializer = getPropertyInitializer(obj,propName)
+        if(initializer){
+            obj[propName] = initializer.initialize()
+        }
+        else{
+            obj[propName] = propertyType.newInstance()
+        }        
+    }
+    
+    protected ValueInitializer getPropertyInitializer(obj, String propName){
+        def initializer = getValueInitializerForField obj, propName
+        initializer
     }
 
+    protected ValueInitializer getValueInitializerForField(obj, String propName) {
+        def initializer
+        try {
+            def field = getField(obj.getClass(), propName)
+            if (field) {
+                def annotation = field.getAnnotation(BindInitializer)
+                if (annotation) {
+                    def valueClass = getValueOfBindInitializer(annotation)
+                    if (Closure.isAssignableFrom(valueClass)) {
+                        Closure closure = (Closure)valueClass.newInstance(null, null)
+                        initializer = new ClosureValueInitializer(initializerClosure: closure.curry(obj), targetType: field.type)
+                    }
+                }
+            }
+        } catch (Exception e) {
+        }
+        initializer
+    }
+    /**
+     * @param annotation An instance of grails.databinding.BindInitializer 
+     * @return the value Class of the annotation
+     */
+    protected Class getValueOfBindInitializer(Annotation annotation) {
+        assert annotation instanceof BindInitializer
+        def value
+        if(annotation instanceof BindInitializer) {
+            value = ((BindInitializer)annotation).value()
+        }
+        value
+    }
+    
     protected convert(Class typeToConvertTo, value) {
         if (value == null || typeToConvertTo.isAssignableFrom(value?.getClass())) {
             return value

grails-databinding/src/main/groovy/grails/databinding/initializers/ValueInitializer.java

@@ -0,0 +1,7 @@
+package grails.databinding.initializers;
+
+
+public interface ValueInitializer {
+    Object initialize();
+    Class<?> getTargetType();
+}

grails-databinding/src/main/groovy/org/grails/databinding/ClosureValueInitializer.groovy

@@ -0,0 +1,17 @@
+package org.grails.databinding
+
+import grails.databinding.initializers.ValueInitializer
+import groovy.transform.CompileStatic
+
+@CompileStatic
+class ClosureValueInitializer implements ValueInitializer {
+
+    Closure initializerClosure
+    Class targetType
+    
+
+    @Override
+    Object initialize() {
+        initializerClosure.call()
+    }
+}

grails-databinding/src/test/groovy/grails/databinding/BindInitializerSpec.groovy

@@ -0,0 +1,32 @@
+package grails.databinding
+
+import spock.lang.Specification
+
+
+class BindInitializerSpec extends Specification {
+    
+    void 'Test BindInitializer for specific property'() {
+        given:
+            def binder = new SimpleDataBinder()
+            def obj = new ClassWithBindInitializerOnProperty()
+        when:
+            binder.bind(obj, new SimpleMapDataBindingSource(['association': [valueBound:'valueBound']]))
+
+        then:
+            obj.association.valueBound == 'valueBound'
+            obj.association.valueInitialized == 'valueInitialized'
+    }
+
+
+    static class ReferencedClass{
+        String valueInitialized
+        String valueBound
+    }
+    class ClassWithBindInitializerOnProperty {
+        @BindInitializer({
+            obj -> 
+                new ReferencedClass(valueInitialized:'valueInitialized')
+        })
+        ReferencedClass association
+    }
+}