An application model is a Spring MVC object that carries attributes from a controller to a view. A controller populates the Model, then returns a logical view name; the view uses those attributes to render a response. section 2.1.2
Supplying a design form
For a GET request to /design, showDesignForm() adds an empty Taco to the Model under the key taco and returns the logical view name taco. The view receives the blank Taco and can render a form for creating it. section 2.1.2
Listing 2.4 The beginnings of a Spring controller class
package tacos.web;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.SessionAttributes;
import lombok.extern.slf4j.Slf4j;
import tacos.Ingredient;
import tacos.Ingredient.Type;
import tacos.Taco;
import tacos.TacoOrder
@Slf4j
@Controller
@RequestMapping("/design")
@SessionAttributes("tacoOrder")
public class DesignTacoController {
@ModelAttribute
public void addIngredientsToModel(Model model) {
List<Ingredient> ingredients = Arrays.asList(
new Ingredient("FLTO", "Flour Tortilla", Type.WRAP),
new Ingredient("COTO", "Corn Tortilla", Type.WRAP),
new Ingredient("GRBF", "Ground Beef", Type.PROTEIN),
new Ingredient("CARN", "Carnitas", Type.PROTEIN),
new Ingredient("TMTO", "Diced Tomatoes", Type.VEGGIES),
new Ingredient("LETC", "Lettuce", Type.VEGGIES),
new Ingredient("CHED", "Cheddar", Type.CHEESE),
new Ingredient("JACK", "Monterrey Jack", Type.CHEESE),
new Ingredient("SLSA", "Salsa", Type.SAUCE),
new Ingredient("SRCR", "Sour Cream", Type.SAUCE)
);
Type[] types = Ingredient.Type.values();
for (Type type : types) {
model.addAttribute(type.toString().toLowerCase(),
filterByType(ingredients, type));
}
}
@ModelAttribute(name = "tacoOrder")
public TacoOrder order() {
return new TacoOrder();
}
@ModelAttribute(name = "taco")
public Taco taco() {
return new Taco();
}
@GetMapping
public String showDesignForm() {
return "design";
}
private Iterable<Ingredient> filterByType(
List<Ingredient> ingredients, Type type) {
return ingredients
.stream()
.filter(x -> x.getType().equals(type))
.collect(Collectors.toList());
}
}
Inspect the controller listing to see Model used alongside @Controller, @RequestMapping, @GetMapping, and @ModelAttribute. section 2.1.2
