QBit, Microservices REST lib, working with Map String, Object for types
When working with REST endpoints at times you want extra capability from one REST end point. To support polymorphic subtypes or operations, you may want to send a wrapper Map that gives some context information. The information could be about what types the sub-maps are.
Let's show a quick example of this using the TodoService from the previous examples. The complete code for this example can be found here Todo Map.
import io.advantageous.boon.core.reflection.MapperSimple;
@RequestMapping(value = "/todo", method = RequestMethod.POST,
description = "add a todo item to the list", summary = "adds todo",
returnDescription = "returns true if successful")
public boolean add(final Map<String, Object> todoMap) {
String id = todoMap.get("id").toString();
String name = (String)todoMap.get("name");
String description = (String)todoMap.get("description");
Long createTime = (Long)todoMap.get("createTime");
Map<String, Object> parent = (Map<String, Object>) todoMap.get("parent");
MapperSimple simple = new MapperSimple();
Category category = simple.fromMap(parent, Category.class);
Todo todo = new Todo(name, description, createTime, category);
todoMap.put(id, todo);
return true;
}Notice that the add method now takes a Map<String, Object> instead of a Todo POJO.
We can pull items out of the map, which equate to properties of a Todo item.
For this example, I changed the Todo to have a property of type Category.
@Description("A `TodoItem`.")
public class Todo {
@Description("Holds the description of the todo item")
private final String description;
@Description("Holds the name of the todo item")
private final String name;
private String id;
private final long createTime;
private final Category parent;
...
public class Category {
private final String name;
public Category(String name) {
this.name = name;
}
}The category payload is expressed as another JSON object, aka, a Java Map Map<String, Object> parent = (Map<String, Object>) todoMap.get("parent");.
We can pull out the sub map which represents the category and use a MapperSimple to convert the map into a POJO (Category).
Map<String, Object> parent = (Map<String, Object>) todoMap.get("parent");
MapperSimple simple = new MapperSimple();
Category category = simple.fromMap(parent, Category.class);
QBit has both a MapperSimple and a MapperComplex, which both implement Mapper. A Mapper converts maps into objects. The MapperComplex allows you to ignore properties, decide how to read fields, etc.
This example was kept fairly simple. You could imagine a more involved example where you read fields and then decide which POJO to instantiate from a list of subclasses.
Read more:
- QBit Microservice Hello World tutorial
- QBit Microservice Hello World Part 2
- QBit Microservice Hello World Health Checks
- QBit Microservice Hello World Stats, Metrics, and Monitoring
- QBit Microservice Reactive programming tutorial
QBit is the Java microservice lib. QBit is a reactive programming lib for building microservices and focuses on JSON, HTTP, WebSocket, and REST. QBit uses reactive programming to build elastic REST, and WebSockets based cloud friendly, web services. SOA evolved for mobile and cloud. ServiceDiscovery, Health, reactive StatService, events, Java idiomatic reactive programming for Microservices.
Reactive Programming, Java Microservices, Rick Hightower
Java Microservices Architecture
[Microservice Service Discovery with Consul] (http:https://www.mammatustech.com/Microservice-Service-Discovery-with-Consul)
Microservices Service Discovery Tutorial with Consul
[Reactive Microservices] (http:https://www.mammatustech.com/reactive-microservices)
[High Speed Microservices] (http:https://www.mammatustech.com/high-speed-microservices)