Beginning JSF™ 2 APIs and JBoss® Seam (Expert's Voice in by Kent Ka Iok Tong

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2: HTTP Request symbol= Symbol is required 3: The symbol has a non-empty value? No. UI Input required: true 1: Mark it as required. sym}" required="true"> ­Figure 2‑12. Marking input as required However, if the UI Command component still sets the outcome to ok, JSF will go ahead and display the stock result. This is obviously not what you want. You’d like to do the following: 1. xhtml. 2. Have it display the error message. In order to do step 1, you need to first understand how JSF handles the request when there is any error in the Input Processing phase, such as when no value is provided but the UI Input component is marked as required (see ­Figure 2‑13).

StockValue}. ... For this to work, define a getter in the b1 bean, as shown in ­Listing 2‑10. ­Listing 2‑10. Providing the Stock Value from the b1 Bean ... hashCode()); } } Run the application, and the stock value should change depending on the symbol. How does it do that? See Figure 2-11. Basically, when the HTTP request arrives, the UI Input and UI Command components are each given the opportunity to handle the request such as reading values from it, checking whether a value is provided, validating the value as needed, and finally storing the value into a web bean (see F ­ igure 2‑11).

Look, store it into the request. Object 3: Create an instance. 2: Look, there is a class with a matching @Named annotation. @Named("foo") @RequestScoped public class GreetingService { public String getSubject() { return "Paul"; } } ­Figure 1‑27. How the Web Beans manager creates the web bean Note that in order for the Web Beans manager to create an instance of the class, it needs to have a ­no-­argument constructor. For the JSF engine to get its subject property, it needs to have a corresponding getter, in other words, getSubject().