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Improvement to support multiple generics class parameters #992

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Aug 12, 2015
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Improvement to support multiple generics class parameters #992

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Improvement to support multiple generics class parameters
francofabio Jul 6, 2015
b419f32
Removed the class TypeExtractor. The extractType method back to IogiP…
francofabio Jul 9, 2015
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10 changes: 3 additions & 7 deletions vraptor-core/src/main/java/br/com/caelum/vraptor/http/iogi/IogiParametersProvider.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@
package br.com.caelum.vraptor.http.iogi;

import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.ArrayList;
Expand All @@ -39,6 +38,7 @@
import br.com.caelum.vraptor.http.Parameter;
import br.com.caelum.vraptor.http.ParameterNameProvider;
import br.com.caelum.vraptor.http.ParametersProvider;
import br.com.caelum.vraptor.util.TypeExtractor;
import br.com.caelum.vraptor.validator.Message;

@RequestScoped
Expand Down Expand Up @@ -90,23 +90,19 @@ private Object instantiateOrAddError(Parameters parameters, List<Message> errors
private List<Target<Object>> createTargets(ControllerMethod method) {
Method javaMethod = method.getMethod();
List<Target<Object>> targets = new ArrayList<>();
TypeExtractor typeExtractor = new TypeExtractor(method.getController().getType());
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what about changing TypeExtractor to be a CDI managed bean?
so it could be specialized -- extensible

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Ok. Good idea.
What is your suggestion of the package for include this class?

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This is really needed? This method is used in one place only. So I'd keep
as private method in the same class, to using kiss principle.
On Jul 6, 2015 15:39, "Rodrigo Turini" [email protected] wrote:

In
vraptor-core/src/main/java/br/com/caelum/vraptor/http/iogi/IogiParametersProvider.java
#992 (comment):

@@ -90,11 +90,12 @@ private Object instantiateOrAddError(Parameters parameters, List errors
private List<Target> createTargets(ControllerMethod method) {
Method javaMethod = method.getMethod();
List<Target> targets = new ArrayList<>();

  •   TypeExtractor typeExtractor = new TypeExtractor(method.getController().getType());

what about changing TypeExtractor to be a CDI managed bean?
so it could be specialized -- extensible

—
Reply to this email directly or view it on GitHub
https://github.com/caelum/vraptor4/pull/992/files#r33967540.

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In the other hand, extracting to a class are giving us the single responsibility principle.
It's a small class, easily testable, with a well-defined purpose. That's why I'm ok with
this change. But sure, we can keep it as a private method. @francofabio it's your call.

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When I created the TypeExtractor class, my intention was to allow this feature to be reused if there was a need.
Thinking about the opinion of @garcia-jj, it makes sense because VRaptor exists a few years ago and yet there was no need to use this feature.
Maybe have less impact on the project if we keep this feature in their own class (private method).
@Turini, What do you think?

** Sorry for my terrible english. :-/

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That sounds great to me, go ahead @francofabio


for (Parameter p : nameProvider.parametersFor(javaMethod)) {
Type type = p.getParameterizedType();
if (type instanceof TypeVariable) {
type = extractType(method);
type = typeExtractor.extractType(type);
}

targets.add(new Target<>(type, p.getName()));
}

return targets;
}

private Type extractType(ControllerMethod method) {
ParameterizedType superclass = (ParameterizedType) method.getController().getType().getGenericSuperclass();
return superclass.getActualTypeArguments()[0];
}

private Parameters parseParameters(HttpServletRequest request) {
Map<String, String[]> parameters = request.getParameterMap();
Expand Down
45 changes: 45 additions & 0 deletions vraptor-core/src/main/java/br/com/caelum/vraptor/util/TypeExtractor.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,45 @@
package br.com.caelum.vraptor.util;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;

import javax.enterprise.inject.Vetoed;

/**
* Extract and resolve type of a generic parameter
*
* @author Fábio Franco
*/
@Vetoed
public class TypeExtractor {

private Class<?> cls;

public TypeExtractor(Class<?> cls) {
this.cls = cls;
}

private Type resolveTypeVariable(TypeVariable<?> type) {
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could you create a few more tests for this method?

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Yes. I do.

ParameterizedType parameterizedType = (ParameterizedType) cls.getGenericSuperclass();
Class<?> rawType = (Class<?>) parameterizedType.getRawType();
TypeVariable<?>[] typeParameters = rawType.getTypeParameters();
if (typeParameters.length > 0) {
for (int i = 0; i < typeParameters.length; i++) {
TypeVariable<?> typeVariable = typeParameters[i];
if (typeVariable.getName().equals(type.getName())) {
return (Class<?>) parameterizedType.getActualTypeArguments()[i];
}
}
}
return type;
}

public Type extractType(Type type) {
if (type instanceof TypeVariable) {
return resolveTypeVariable((TypeVariable<?>) type);
}
return type;
}

}
23 changes: 23 additions & 0 deletions vraptor-core/src/test/java/br/com/caelum/vraptor/http/iogi/IogiParametersProviderTest.java
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Expand Up @@ -148,6 +148,21 @@ public void isCapableOfDealingWithGenerics() throws Exception {
assertThat(abc.x, is(123l));
}

@Test
public void isCapableOfDealingWithGenericsAndMultipleParameters() throws Exception {
requestParametersAre(ImmutableMap.of("key", new String[] { "age" }, "value", new String[] { "32" }));

ControllerMethod generic = method(SpecificKeyValueResource.class, GenericKeyValueResource.class, "put", Object.class, Object.class);
Object[] params = iogi.getParametersFor(generic, errors);
String key = (String) params[0];
Long value = (Long) params[1];

assertThat(key, is("age"));
assertThat(value, notNullValue());
assertThat(value, instanceOf(Long.class));
assertThat(value, is(32L));
}

@Test
public void isCapableOfDealingWithIndexedLists() throws Exception {
requestParameterIs("abc[2]", "1");
Expand Down Expand Up @@ -602,6 +617,14 @@ void generic(T t) { }

static class Specific extends Generic<ABC> {
}

static class GenericKeyValueResource<K, V> {
void put(K key, V value) { }
}

static class SpecificKeyValueResource extends GenericKeyValueResource<String, Long> {

}

public static class Cat {
private String id;
Expand Down