prepare for persistent domain classes

docs/week05/README-5-Persistence.md

@@ -0,0 +1,40 @@
+# WebEngineering Module, Persistence
+
+## Goals
+
+### Abilities
+- From a greenfield, being able to use a relational database with create-read-update-delete (CRUD)
+  functionality in a webapp. 
+- Use of simple entities, many-to-one, and many-to-many relations.   
+
+### Knowledge
+- Understanding Grails domain classes as simple entities.
+- Understanding Grails domain classes with references as relations.
+- Understanding dynamic finder methods
+
+## Resources
+
+http://docs.grails.org/latest/guide/GORM.html
+
+## Demo / Live-coding
+
+- Creating a room reservation system
+- Domain classes: Room, Person, Booking (very simple)
+- Static scaffolding 
+- Setting up bootstrap data
+- Use Controller actions to interact with the domain model
+
+## practical work
+
+- create an action that displays all bookings of a given person
+- create an action that displays all available rooms for a requested time slot today
+
+## Homework 
+
+Finish the practical work
+
+Build on the practical work from above to 
+create a full Web MVC-Cycle (without scaffolding) that shows
+
+- all bookings from today until eternity for a given person
+- all available rooms for a requested day and time slot

grails-app/init/rooms/BootStrap.groovy

@@ -1,9 +1,47 @@
 package rooms
 
+import grails.util.Environment
+
+import java.time.LocalDate
+
 class BootStrap {
 
+    static Date today      = toUtilDate(LocalDate.now())
+    static Date tomorrow   = toUtilDate(LocalDate.now().plusDays(1))
+    static Date yesterday  = toUtilDate(LocalDate.now().minusDays(1))
+
+    /**
+     * This method is called when the server starts.
+     */
     def init = { servletContext ->
+
+        if (Environment.current == Environment.PRODUCTION) { // guard clause
+            return
+        }
+
+
     }
+
     def destroy = {
     }
-}
+
+    /**
+     * Convenience method to save a domain object and throw an exception if validation fails.
+     * @param domainObject
+     * @return Object - the saved domain object
+     */
+    static <T> T save(T domainObject) {
+        domainObject.save(failOnError: true) // will throw an exception if validation fails
+        return domainObject
+    }
+
+    /**
+     * Convenience method to convert a LocalDate to a java.util.Date
+     * @param localDate
+     * @return Date - a java.util.Date
+     */
+    static Date toUtilDate(LocalDate localDate) {
+        // this is not the best way to do it in general but it works for our purposes
+        return new Date(localDate.toEpochDay() * 24 * 60 * 60 * 1000)
+    }
+}