As per the title, I'm seeing that my read-only model properties are not serialized in my Web API project. MVC 4 Web API, VS2010.
I've seen a multitude of posts like this stackoverflow question that state that the MVC 4 Web API beta did not support JSON serializing of read-only properties. But many additional references stated that the final release used JSON.NET instead of DataContractJsonSerializer so the issue should be resolved.
Has this issue been resolved or not? If not, am I forced to put in fake setters just to get serialization?
Correction, it does seem to work with JSON (sorry!), but XML exhibits the problem. So same question as before but in the context of XML serialization.
The default JSON serializer is now Json.NET. So readonly property serialization should work without you having to do anything at all.
For XML, in 4.5 we added this flag to the DataContractSerializer:
http://msdn.microsoft.com/en-us/library/vstudio/system.runtime.serialization.datacontractserializersettings.serializereadonlytypes.aspx
You should be able to write something like this:
config.Formatters.XmlFormatter.SetSerializer(myType, new DataContractSerializer(myType, new DataContractSerializerSettings() { SerializeReadOnlyTypes = true });
Place this code in a function called by GlobalConfiguration.Configure in the Application_Start. By default this would be WebApiConfig.Register().
Related
I am writing a custom OpenApiConfigurator that adds some examples to my api dynamically.
When I add the examples using the value field of io.smallrye.openapi.api.models.examples.ExampleImpl, which is an object, the example is null in swagger-ui. It only works when I added the actual json.
To add the actual json I have to generate it from my response dto using Jackson. But how can I access the quarkus object mapper, for which I have some customisations using ObjectMapperCustomizer, if in the OpenApiConfigurator CDI is not available?
It's actually possible to access the CDI container statically with Arc.container().instance(ObjectMapper::class.java).get()
That solved it for me.
I am currently working on a Spring Boot project and I am fairly new to template engines. This will also be my first own private project with Spring Boot.
I would like to know whether it is necessary to include a template engine, such as Thymeleaf, while developing a web application with Spring Boot. I'm using PostegreSQL for the database.
I read under another post that a template engine is not needed, if the backend framework uses JSON for data exchange, because template engines are for rendering retrieved data to HTML for the client. I retrieve JSON objects from the database, can I leave template engines out of my project then?
If any more details are needed, leave a comment below.
No they aren't necessary, in fact most new projects that require web-pages are using single page applications now like Angular, React, Vue, ... over thymeleaf or jsp.
Aside from that a Spring project doesn't always need web pages, for instance when you are just creating a REST API for other applications to call on, or when you are automating things like: a mail service / printing / ... You name it.
However, when you DO want a simple solution with some pages that aren't all that dynamic or complex, pivotal / VMware does recommend to use thymeleaf (over jsp and other solutions) because it integrates easily.
I read under another post that a template engine is not needed, if the backend framework uses JSON for data exchange, because template engines are for rendering retrieved data to HTML for the client. I retrieve JSON objects from the database, can I leave template engines out of my project then?
This is partly true. Yes, Thymeleaf and alike are mostly intended to render data to HTML. They can render any text data, including JSON, but there are tools better suited for the job. On other hand it does not matter how you store the data in your database or what database you are using. You can't just skip rendering (serializing) the response so it does not matter how you store it. What matters is what you want to return as response. For HTML Thymeleaf or even JSP are suitable, but for JSON you may want to use Jackson or Gson instead.
You didn't mentioned the technology you are going to use, so for my examples I'll assume you intend to use Spring Web MVC. Lets take a look at "traditional" controller:
#Controller
public class GreetingController {
#GetMapping("/greeting")
public ModelAndView greeting(#RequestParam(value = "name", defaultValue = "World") String name) {
return new ModelAndView("greeting", "greeting", new Greeting(name));
}
}
When you make GET request to "/greeting", Spring will call greeting and get the object it returns. In this case it contains the model (the data we want to render) and the view (the template file to use). Then it will try to find a view (something like greeting.html or greeting.jsp) and use template engine like Thymeleaf (or whatever else is configured) to render it (typically to HTML).
What if we want to return JSON instead? In this case we need to:
modify greeting to return Greeting instance instead of ModelAndView
Use RestController instead of Controller. This will tell Spring MVC that we want to directly serialize the object returned to JSON (or similar format) instead of using template to do that.
Here is the modified example:
#RestController
public class GreetingController {
#GetMapping("/greeting")
public Greeting greeting(#RequestParam(value = "name", defaultValue = "World") String name) {
return new Greeting(name);
}
}
Spring MVC still needs some help to serialize the Greeting instance to JSON. But if you use Spring Boot and the web starter, you don't have to worry about it. It will include Jackson for you.
This is in no way exhaustive answer. As a matter of fact it skips a lot of details, but I hope nevertheless it is useful one. If you want to create REST API using JSON, this Building a RESTful Web Service guide is a good place to start. If you follow the Starting with Spring Initializr steps you'll get a project setup with only what is needed (well maybe with a bit extra but I would not worry too much about it).
I've decided to use custom template engine with Spring MVC framework.
my templates implemented in java and have method for rendering into String:
public String render(Map context);
how to configure spring to make them available in Controller beans as views, for example like:
ModelAndView modelAndView = new ModelAndView("activationPage"); // - view name which will actually be java class name reference.
modelAndView.addObject("validationResult", validationResult);
return modelAndView;
Model will be passed as context in code connecting spring and my template engine.
You need to implement org.springframework.web.servlet.View (which should be easy, you already have something very similar to the render method it needs), as well as org.springframework.web.servlet.ViewResolver, which maps the view names (e.g. "activationPage") on your custom views.
Once you have that, drop a bean of your ViewResolver class into the context, and (unless you've done something else that gets in the way) it should automatically be picked up by Spring and should just work. if you have other ViewResolvers already in there, they may get into a fight over who gets to resolve the view, in which case ask a new question.
Hi I am the author of Rythm template engine, about half year ago I am having the same requirement like you. What I did is to read the source code of Velocity and Freemarker view of SpringFramework. And then create the Rythm view for spring following their approach.
It's easy to follow something that is already there, and it makes your implementation in good quality to follow the official module. Good luck on you :-)
I have a Spring MVC application which returns Json and Xml based on what is requested per client call. I am using Jackson and Xstream to let Spring do the de-serialization of my java object into json or xml output.
My java object contains a bunch of attributes, at least 30. I would like to know if there is a way I can let Spring control which fields of my java object will be present in the json or xml based on a header or parameter attribute. So the client application will be able to identify itself and the backend will return only the fields necessary or "visible" for that specific client app. Of course I could go to the nasty approach of hard coding, but I would not like to do that as the number of client applications can increase or decrease and having a deployment anytime it happens with code changes is out of context.
Is there a way to instruct spring/jackson/xstream to control the output based on some providaded value?
I did a quick implementation and my current solution works like this: I have an xml with a list of client IDs (I use these ids to identify my client app) and for each ID I have a list of attributes that the client app needs from the java object. I created a interceptor and between the controller and the view, my interceptor gets the header information with the client ID, get the list of attributes and using the BeanWrapper (http://docs.spring.io/spring/docs/2.0.x/reference/validation.html) to create a new object with only the attributes required by the client with data, all the others remain null (I instruct Jackson and Xtream) to ignore null attributes. This approach works fine but I was wondering if there is another/better way to do this.
Thank you
TL
I primarily use annotated controllers that return ModelAndView object used by Spring and Freemarker to render and return pages to browsers - works great. I'd now like to respond to ajax gets and posts that return html fragments as payload inside an XML message.
The problem I'm having not returning a ModelAndView objects seems to confuse Spring WRT to #ModelAttribute (s) and session objects that support data to / and from forms.
I've had to hack the freemarker template to support i18n messages, etc. I'm finding that simply rendering an FTL file while also trying to utilize Spring's object rendering from froms is becoming quite a rabbit hole.
I'm trying to manually (guess what and) do the things that get done behind the scenes and it's not working optimally. To edit an object I'm manually placing the object in the session on rendering the edit form. When the post comes back there are residual/different values in the object I get back out of the session AND the ModelAttribute that Spring rendered for me.
Bottom line? Questions about Spring, Freemarker and custom non-ModelAndView responses that are rendered by Freemarker.
Add another instance of FreeMarkerViewResolver that only that has viewNames ='*.frg'. The viewClass should be your own class that renders the template the way you want by overriding the processTemplate method.