I have a Nancy module which uses a function which expects as parameters a string (a captured pattern from a route) and a method group. When trying to pass the parameter directly it will not compile as I "cannot use a method group as an argument to a dynamically dispatched operation".
I have created a second route which attempts to cast the dynamic to a string, but this always returns null.
using System;
using Nancy;
public class MyModule : NancyModule
{
public MyModule()
{
//Get["/path/{Name}/action"] = parameters =>
// {
// return MyMethod(parameters.Name, methodToBeCalled); // this does not compile
// };
Get["/path/{Name}/anotherAction"] = parameters =>
{
return MyMethod(parameters.Name as string, anotherMethodToBeCalled);
};
}
public Response MyMethod(string name, Func<int> doSomething)
{
doSomething();
return Response.AsText(string.Format("Hello {0}", name));
}
public int methodToBeCalled()
{
return -1;
}
public int anotherMethodToBeCalled()
{
return 1;
}
}
Tested with the following class in a separate project:
using System;
using Nancy;
using Nancy.Testing;
using NUnit.Framework;
[TestFixture]
public class MyModuleTest
{
Browser browser;
[SetUp]
public void SetUp()
{
browser = new Browser(with =>
{
with.Module<MyModule>();
with.EnableAutoRegistration();
});
}
[Test]
public void Can_Get_View()
{
// When
var result = browser.Get("/path/foobar/anotherAction", with => with.HttpRequest());
// Then
Assert.AreEqual(HttpStatusCode.OK, result.StatusCode);
Assert.AreEqual("Hello foobar", result.Body.AsString()); //fails as parameters.Name is always null when cast to a string
}
}
You can find the whole test over on github
I've had similar issues when using 'as' so I tend to use explicitly cast it:
return MyMethod((string)parameters.Name, anotherMethodToBeCalled);
Also I think there was a bug raised with the casing on parameters, but I think it's better to keep them lowercase:
Get["/path/{name}/anotherAction"]
(string)parameters.name
Your code works for me with upper case and lowercase, using the explicit cast.
Related
I want to use a UUID as a part of a URL:
https://example.com/books/fiction/don-quixote-37d8d0a6-692a-11ed-9022-0242ac120002
Where in my controller should I generate this UUD?
class BookController extends Controller
{
public function store(BookStoreRequest $request)
{
$this->authorize('create', Book::class);
$validated = $request->validated();
$validated['identifier'] = (string) Str::uuid();
$book = Book::create($validated);
}
}
Above results in the error:
SQLSTATE Field 'identifier' doesn't have a default value
This assume that the value for identifier wasn't passed correctly?
Solution is to add a boot function to the model:
public static function boot()
{
parent::boot();
static::creating(function ($model) {
$model->identifier = Str::uuid();
});
}
This might be a duplicate. But I cannot find a solution to my Problem.
I have a class
public class MyResponse implements Serializable {
private boolean isSuccess;
public boolean isSuccess() {
return isSuccess;
}
public void setSuccess(boolean isSuccess) {
this.isSuccess = isSuccess;
}
}
Getters and setters are generated by Eclipse.
In another class, I set the value to true, and write it as a JSON string.
System.out.println(new ObjectMapper().writeValueAsString(myResponse));
In JSON, the key is coming as {"success": true}.
I want the key as isSuccess itself. Is Jackson using the setter method while serializing? How do I make the key the field name itself?
This is a slightly late answer, but may be useful for anyone else coming to this page.
A simple solution to changing the name that Jackson will use for when serializing to JSON is to use the #JsonProperty annotation, so your example would become:
public class MyResponse implements Serializable {
private boolean isSuccess;
#JsonProperty(value="isSuccess")
public boolean isSuccess() {
return isSuccess;
}
public void setSuccess(boolean isSuccess) {
this.isSuccess = isSuccess;
}
}
This would then be serialised to JSON as {"isSuccess":true}, but has the advantage of not having to modify your getter method name.
Note that in this case you could also write the annotation as #JsonProperty("isSuccess") as it only has the single value element
I recently ran into this issue and this is what I found. Jackson will inspect any class that you pass to it for getters and setters, and use those methods for serialization and deserialization. What follows "get", "is" and "set" in those methods will be used as the key for the JSON field ("isValid" for getIsValid and setIsValid).
public class JacksonExample {
private boolean isValid = false;
public boolean getIsValid() {
return isValid;
}
public void setIsValid(boolean isValid) {
this.isValid = isValid;
}
}
Similarly "isSuccess" will become "success", unless renamed to "isIsSuccess" or "getIsSuccess"
Read more here: http://www.citrine.io/blog/2015/5/20/jackson-json-processor
Using both annotations below, forces the output JSON to include is_xxx:
#get:JsonProperty("is_something")
#param:JsonProperty("is_something")
When you are using Kotlin and data classes:
data class Dto(
#get:JsonProperty("isSuccess") val isSuccess: Boolean
)
You might need to add #param:JsonProperty("isSuccess") if you are going to deserialize JSON as well.
EDIT: If you are using swagger-annotations to generate documentation, the property will be marked as readOnly when using #get:JsonProperty. In order to solve this, you can do:
#JsonAutoDetect(isGetterVisibility = JsonAutoDetect.Visibility.NONE)
data class Dto(
#field:JsonProperty(value = "isSuccess") val isSuccess: Boolean
)
You can configure your ObjectMapper as follows:
mapper.setPropertyNamingStrategy(new PropertyNamingStrategy() {
#Override
public String nameForGetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName)
{
if(method.hasReturnType() && (method.getRawReturnType() == Boolean.class || method.getRawReturnType() == boolean.class)
&& method.getName().startsWith("is")) {
return method.getName();
}
return super.nameForGetterMethod(config, method, defaultName);
}
});
I didn't want to mess with some custom naming strategies, nor re-creating some accessors.
The less code, the happier I am.
This did the trick for us :
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonProperty;
#JsonIgnoreProperties({"success", "deleted"}) // <- Prevents serialization duplicates
public class MyResponse {
private String id;
private #JsonProperty("isSuccess") boolean isSuccess; // <- Forces field name
private #JsonProperty("isDeleted") boolean isDeleted;
}
Building upon Utkarsh's answer..
Getter names minus get/is is used as the JSON name.
public class Example{
private String radcliffe;
public getHarryPotter(){
return radcliffe;
}
}
is stored as { "harryPotter" : "whateverYouGaveHere" }
For Deserialization, Jackson checks against both the setter and the field name.
For the Json String { "word1" : "example" }, both the below are valid.
public class Example{
private String word1;
public setword2( String pqr){
this.word1 = pqr;
}
}
public class Example2{
private String word2;
public setWord1(String pqr){
this.word2 = pqr ;
}
}
A more interesting question is which order Jackson considers for deserialization. If i try to deserialize { "word1" : "myName" } with
public class Example3{
private String word1;
private String word2;
public setWord1( String parameter){
this.word2 = parameter ;
}
}
I did not test the above case, but it would be interesting to see the values of word1 & word2 ...
Note: I used drastically different names to emphasize which fields are required to be same.
You can change primitive boolean to java.lang.Boolean (+ use #JsonPropery)
#JsonProperty("isA")
private Boolean isA = false;
public Boolean getA() {
return this.isA;
}
public void setA(Boolean a) {
this.isA = a;
}
Worked excellent for me.
If you are interested in handling 3rd party classes not under your control (like #edmundpie mentioned in a comment) then you add Mixin classes to your ObjectMapper where the property/field names should match the ones from your 3rd party class:
public class MyStack32270422 {
public static void main(String[] args) {
ObjectMapper om3rdParty = new ObjectMapper();
om3rdParty .addMixIn(My3rdPartyResponse.class, MixinMyResponse.class);
// add further mixins if required
String jsonString = om3rdParty.writeValueAsString(new My3rdPartyResponse());
System.out.println(jsonString);
}
}
class MixinMyResponse {
// add all jackson annotations here you want to be used when handling My3rdPartyResponse classes
#JsonProperty("isSuccess")
private boolean isSuccess;
}
class My3rdPartyResponse{
private boolean isSuccess = true;
// getter and setter here if desired
}
Basically you add all your Jackson annotations to your Mixin classes as if you would own the class. In my opinion quite a nice solution as you don't have to mess around with checking method names starting with "is.." and so on.
there is another method for this problem.
just define a new sub-class extends PropertyNamingStrategy and pass it to ObjectMapper instance.
here is a code snippet may be help more:
mapper.setPropertyNamingStrategy(new PropertyNamingStrategy() {
#Override
public String nameForGetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName) {
String input = defaultName;
if(method.getName().startsWith("is")){
input = method.getName();
}
//copy from LowerCaseWithUnderscoresStrategy
if (input == null) return input; // garbage in, garbage out
int length = input.length();
StringBuilder result = new StringBuilder(length * 2);
int resultLength = 0;
boolean wasPrevTranslated = false;
for (int i = 0; i < length; i++)
{
char c = input.charAt(i);
if (i > 0 || c != '_') // skip first starting underscore
{
if (Character.isUpperCase(c))
{
if (!wasPrevTranslated && resultLength > 0 && result.charAt(resultLength - 1) != '_')
{
result.append('_');
resultLength++;
}
c = Character.toLowerCase(c);
wasPrevTranslated = true;
}
else
{
wasPrevTranslated = false;
}
result.append(c);
resultLength++;
}
}
return resultLength > 0 ? result.toString() : input;
}
});
The accepted answer won't work for my case.
In my case, the class is not owned by me. The problematic class comes from 3rd party dependencies, so I can't just add #JsonProperty annotation in it.
To solve it, inspired by #burak answer above, I created a custom PropertyNamingStrategy as follow:
mapper.setPropertyNamingStrategy(new PropertyNamingStrategy() {
#Override
public String nameForSetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName)
{
if (method.getParameterCount() == 1 &&
(method.getRawParameterType(0) == Boolean.class || method.getRawParameterType(0) == boolean.class) &&
method.getName().startsWith("set")) {
Class<?> containingClass = method.getDeclaringClass();
String potentialFieldName = "is" + method.getName().substring(3);
try {
containingClass.getDeclaredField(potentialFieldName);
return potentialFieldName;
} catch (NoSuchFieldException e) {
// do nothing and fall through
}
}
return super.nameForSetterMethod(config, method, defaultName);
}
#Override
public String nameForGetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName)
{
if(method.hasReturnType() && (method.getRawReturnType() == Boolean.class || method.getRawReturnType() == boolean.class)
&& method.getName().startsWith("is")) {
Class<?> containingClass = method.getDeclaringClass();
String potentialFieldName = method.getName();
try {
containingClass.getDeclaredField(potentialFieldName);
return potentialFieldName;
} catch (NoSuchFieldException e) {
// do nothing and fall through
}
}
return super.nameForGetterMethod(config, method, defaultName);
}
});
Basically what this does is, before serializing and deserializing, it checks in the target/source class which property name is present in the class, whether it is isEnabled or enabled property.
Based on that, the mapper will serialize and deserialize to the property name that is exist.
I'm trying to translate a ParameterizedTest from JUnit4 to JUnit5 (sadly I'm not particularly skilled in testing).
In JUnit4 I have the following class:
#RunWith(Parameterized.class)
public class AssertionTestCase {
private final TestInput testInput;
public AssertionTestCase(TestInput testInput) {
this.testInput = testInput;
}
#Parameterized.Parameters
public static Collection<Object[]> data() {
return AssertionTestCaseDataProvider.createDataCase();
}
#Test(timeout = 15 * 60 * 1000L)
public void testDailyAssertion() {
LOG.info("Testing input {}/{}", testInput.getTestCase(), testInput.getTestName());
//assert stuffs
}
}
in the AssertionTestCaseDataProvider class I have a simple method generating a collection of Object[]:
class AssertionTestCaseDataProvider {
static Collection<Object[]> createDataCase() {
final List<TestInput> testInputs = new ArrayList<>();
//create and populate testInputs
return testInputs.stream()
.map(testInput -> new Object[]{testInput})
.collect(Collectors.toList());
}
}
I've been trying to translate it using JUnit5 and obtained this:
class AssertionTestCase {
private final TestInput testInput;
public AssertionTestCase(TestInput testInput) {
this.testInput = testInput;
}
public static Collection<Object[]> data() {
return AssertionTestCaseDataProvider.createDataCase();
}
#ParameterizedTest
#MethodSource("data")
void testDailyAssertion() {
LOG.info("Testing input {}/{}", testInput.getTestCase(), testInput.getTestName());
// assert stuffs
}
}
I did not apply any change to the AssertionTestCaseDataProvider class.
Nevertheless, I'm getting the following error:
No ParameterResolver registered for parameter [com.xxx.xx.xxx.xxx.testinput.TestInput arg0] in constructor [public `com.xxx.xxx.xxx.xxx.xxx.AssertionTestCase(com.xxx.xxx.xxx.xxx.testinput.TestInput)]. org.junit.jupiter.api.extension.ParameterResolutionException: No ParameterResolver registered for parameter [com.xxx.xx.xxx.xxx.testinput.TestInput arg0] in constructor [public com.xxx.xxx.xxx.xxx.xxx.AssertionTestCase(com.xxx.xxx.xxx.xxx.testinput.TestInput)].`
I understand I'm probably not applying correctly JUnit5 when initializing the input collection for the test. Am I missing some annotations?
I've also tried to use #ArgumentSource instead of #MethodSource and implementing Argument for AssertionTestCaseDataProvider, with the same failing results.
It works in a bit another way in Junit5.
Test Method should have parameters, and provider method should return a Stream.
static Stream<Arguments> data(){
return Stream.of(
Arguments.of("a", 1),
Arguments.of("d", 2)
);
}
#ParameterizedTest
#MethodSource("data")
void testDailyAssertion(String a, int b) {
Assertions.assertAll(
() -> Assertions.assertEquals("a", a),
() -> Assertions.assertEquals(1, b)
);
}
In your case you can just return a Stream<TestInput>:
static Stream<TestInput> createDataCase() {
final List<TestInput> testInputs = new ArrayList<>();
//create and populate testInputs
return testInputs.stream();
}
and then in your testMethod:
#ParameterizedTest
#MethodSource("createDataCase")
void testDailyAssertion(TestInput testInput) {
{your assertions}
}
My following straight forward test doesn't pass (Though I feel it should). Either I am missing something or is not clear of Property.value constraint. please help me in understanding concept of property.value constraint.
public interface ISomeInterface
{
void SomeMethod(string x, string y);
}
public class SomeClassTest
{
[Test]
public void SomeMethodTest()
{
MockRepository mocks = new MockRepository();
ISomeInterface mockservice = mocks.StrictMock<ISomeInterface>();
using (mocks.Record())
{
mockservice.SomeMethod("xValue", "yValue");
LastCall.Constraints(Property.Value("x", "xValue"),
Property.Value("y", "yValue"));
}
mockservice.SomeMethod("xValue", "yValue");
mocks.Verify(mockservice);
}
}
Exception raised:
Rhino.Mocks.Exceptions.ExpectationViolationException : ISomeInterface.SomeMethod("xValue", "yValue"); Expected #0, Actual #1.
ISomeInterface.SomeMethod(property 'x' equal to xValue, property 'y' equal to yValue); Expected #1, Actual #0.
I would recommend you the following syntax (AAA syntax):
// arrange
var mockservice = MockRepository.GenerateMock<ISomeInterface>();
// act
mockservice.SomeMethod("xValue", "yValue");
// assert
mockservice.AssertWasCalled(
x => x.SomeMethod("xValue", "yValue")
);
This sample class illustrates the options for asserting methods were called with appropriate properties:
public class UsesThing
{
private IMyThing _thing;
public UsesThing(IMyThing thing)
{
_thing = thing;
}
public void DoTheThing(int myparm)
{
_thing.DoWork(myparm, Helper.GetParmString(myparm));
}
public void DoAnotherThing(int myparm)
{
AnotherThing thing2 = new AnotherThing();
thing2.MyProperty = myparm + 2;
_thing.DoMoreWork(thing2)
}
}
Using simple values for assertions may work for methods like the DoTheThing method which uses value types:
[Test]
public void TestDoTheThing()
{
IMyThing thing = MockRepository.GenerateMock<IMyThing>();
UsesThing user = new UsesThing(thing);
user.DoTheThing(1);
thing.AssertWasCalled(t => t.DoWork(1, "one");
}
However, if you need to create an object in your method and pass it as a parameter like in the DoAnotherThing method, this approach will not work since you will not have a reference to the object. You have to check the property values of the unknown object, like this:
[Test]
public void TestDoAnotherThing()
{
IMyThing thing = MockRepository.GenerateMock<IMyThing>();
UsesThing user = new UsesThing(thing);
user.DoAnotherThing(1);
thing.AssertWasCalled(t => t.DoMoreWork(null), t => t.IgnoreArguments().Constraints(Property.Value("MyProperty", 3))));
}
The new Rhino syntax would look like the following, but I am crashing VS 2008 when I use it:
thing.AssertWasCalled(t => t.DoMoreWork(Arg<AnotherThing>.Matches(Property.Value("MyProperty", 3))));
I'm wanting to have a simple duck typing example in C# using dynamic objects. It would seem to me, that a dynamic object should have HasValue/HasProperty/HasMethod methods with a single string parameter for the name of the value, property, or method you are looking for before trying to run against it. I'm trying to avoid try/catch blocks, and deeper reflection if possible. It just seems to be a common practice for duck typing in dynamic languages (JS, Ruby, Python etc.) that is to test for a property/method before trying to use it, then falling back to a default, or throwing a controlled exception. The example below is basically what I want to accomplish.
If the methods described above don't exist, does anyone have premade extension methods for dynamic that will do this?
Example: In JavaScript I can test for a method on an object fairly easily.
//JavaScript
function quack(duck) {
if (duck && typeof duck.quack === "function") {
return duck.quack();
}
return null; //nothing to return, not a duck
}
How would I do the same in C#?
//C# 4
dynamic Quack(dynamic duck)
{
//how do I test that the duck is not null,
//and has a quack method?
//if it doesn't quack, return null
}
If you have control over all of the object types that you will be using dynamically, another option would be to force them to inherit from a subclass of the DynamicObject class that is tailored to not fail when a method that does not exist is invoked:
A quick and dirty version would look like this:
public class DynamicAnimal : DynamicObject
{
public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)
{
bool success = base.TryInvokeMember(binder, args, out result);
// If the method didn't exist, ensure the result is null
if (!success) result = null;
// Always return true to avoid Exceptions being raised
return true;
}
}
You could then do the following:
public class Duck : DynamicAnimal
{
public string Quack()
{
return "QUACK!";
}
}
public class Cow : DynamicAnimal
{
public string Moo()
{
return "Mooooo!";
}
}
class Program
{
static void Main(string[] args)
{
var duck = new Duck();
var cow = new Cow();
Console.WriteLine("Can a duck quack?");
Console.WriteLine(DoQuack(duck));
Console.WriteLine("Can a cow quack?");
Console.WriteLine(DoQuack(cow));
Console.ReadKey();
}
public static string DoQuack(dynamic animal)
{
string result = animal.Quack();
return result ?? "... silence ...";
}
}
And your output would be:
Can a duck quack?
QUACK!
Can a cow quack?
... silence ...
Edit: I should note that this is the tip of the iceberg if you are able to use this approach and build on DynamicObject. You could write methods like bool HasMember(string memberName) if you so desired.
Try this:
using System.Linq;
using System.Reflection;
//...
public dynamic Quack(dynamic duck, int i)
{
Object obj = duck as Object;
if (duck != null)
{
//check if object has method Quack()
MethodInfo method = obj.GetType().GetMethods().
FirstOrDefault(x => x.Name == "Quack");
//if yes
if (method != null)
{
//invoke and return value
return method.Invoke((object)duck, null);
}
}
return null;
}
Or this (uses only dynamic):
public static dynamic Quack(dynamic duck)
{
try
{
//invoke and return value
return duck.Quack();
}
//thrown if method call failed
catch (RuntimeBinderException)
{
return null;
}
}
Implementation of the HasProperty method for every IDynamicMetaObjectProvider WITHOUT throwing RuntimeBinderException.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Dynamic;
using Microsoft.CSharp.RuntimeBinder;
using System.Linq.Expressions;
using System.Runtime.CompilerServices;
namespace DynamicCheckPropertyExistence
{
class Program
{
static void Main(string[] args)
{
dynamic testDynamicObject = new ExpandoObject();
testDynamicObject.Name = "Testovaci vlastnost";
Console.WriteLine(HasProperty(testDynamicObject, "Name"));
Console.WriteLine(HasProperty(testDynamicObject, "Id"));
Console.ReadLine();
}
private static bool HasProperty(IDynamicMetaObjectProvider dynamicProvider, string name)
{
var defaultBinder = Binder.GetMember(CSharpBinderFlags.None, name, typeof(Program),
new[]
{
CSharpArgumentInfo.Create(
CSharpArgumentInfoFlags.None, null)
}) as GetMemberBinder;
var callSite = CallSite<Func<CallSite, object, object>>.Create(new NoThrowGetBinderMember(name, false, defaultBinder));
var result = callSite.Target(callSite, dynamicProvider);
if (Object.ReferenceEquals(result, NoThrowExpressionVisitor.DUMMY_RESULT))
{
return false;
}
return true;
}
}
class NoThrowGetBinderMember : GetMemberBinder
{
private GetMemberBinder m_innerBinder;
public NoThrowGetBinderMember(string name, bool ignoreCase, GetMemberBinder innerBinder) : base(name, ignoreCase)
{
m_innerBinder = innerBinder;
}
public override DynamicMetaObject FallbackGetMember(DynamicMetaObject target, DynamicMetaObject errorSuggestion)
{
var retMetaObject = m_innerBinder.Bind(target, new DynamicMetaObject[] {});
var noThrowVisitor = new NoThrowExpressionVisitor();
var resultExpression = noThrowVisitor.Visit(retMetaObject.Expression);
var finalMetaObject = new DynamicMetaObject(resultExpression, retMetaObject.Restrictions);
return finalMetaObject;
}
}
class NoThrowExpressionVisitor : ExpressionVisitor
{
public static readonly object DUMMY_RESULT = new DummyBindingResult();
public NoThrowExpressionVisitor()
{
}
protected override Expression VisitConditional(ConditionalExpression node)
{
if (node.IfFalse.NodeType != ExpressionType.Throw)
{
return base.VisitConditional(node);
}
Expression<Func<Object>> dummyFalseResult = () => DUMMY_RESULT;
var invokeDummyFalseResult = Expression.Invoke(dummyFalseResult, null);
return Expression.Condition(node.Test, node.IfTrue, invokeDummyFalseResult);
}
private class DummyBindingResult {}
}
}
impromptu-interface seems to be a nice Interface mapper for dynamic objects... It's a bit more work than I was hoping for, but seems to be the cleanest implementation of the examples presented... Keeping Simon's answer as correct, since it is still the closest to what I wanted, but the Impromptu interface methods are really nice.
The shortest path would be to invoke it, and handle the exception if the method does not exist. I come from Python where such method is common in duck-typing, but I don't know if it is widely used in C#4...
I haven't tested myself since I don't have VC 2010 on my machine
dynamic Quack(dynamic duck)
{
try
{
return duck.Quack();
}
catch (RuntimeBinderException)
{ return null; }
}
Have not see a correct answer here, MS provides an example now with casting to a dictionary
dynamic employee = new ExpandoObject();
employee.Name = "John Smith";
employee.Age = 33;
foreach (var property in (IDictionary<String, Object>)employee)
{
Console.WriteLine(property.Key + ": " + property.Value);
}
// This code example produces the following output:
// Name: John Smith
// Age: 33