# VisitController.java

    /*
     * Copyright 2012-2019 the original author or authors.
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at
     *
     *      https://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    package org.springframework.samples.petclinic.owner;

    import org.springframework.samples.petclinic.visit.Visit;
    import org.springframework.samples.petclinic.visit.VisitRepository;
    import org.springframework.stereotype.Controller;
    import org.springframework.validation.BindingResult;
    import org.springframework.web.bind.WebDataBinder;
    import org.springframework.web.bind.annotation.*;

    import javax.validation.Valid;
    import java.util.Map;

    /**
     * @author Juergen Hoeller
     * @author Ken Krebs
     * @author Arjen Poutsma
     * @author Michael Isvy
     * @author Dave Syer
     */
    @Controller
    class VisitController {

        private final VisitRepository visits;
        private final PetRepository pets;

        public VisitController(VisitRepository visits, PetRepository pets) {
            this.visits = visits;
            this.pets = pets;
        }

        @InitBinder
        public void setAllowedFields(WebDataBinder dataBinder) {
            dataBinder.setDisallowedFields("id");
        }

        /**
         * Called before each and every @RequestMapping annotated method.
         * 2 goals:
         * - Make sure we always have fresh data
         * - Since we do not use the session scope, make sure that Pet object always has an id
         * (Even though id is not part of the form fields)
         *
         * @param petId
         * @return Pet
         */
        @ModelAttribute("visit")
        public Visit loadPetWithVisit(@PathVariable("petId") int petId, Map<String, Object> model) {
            Pet pet = this.pets.findById(petId);
            model.put("pet", pet);
            Visit visit = new Visit();
            pet.addVisit(visit);
            return visit;
        }

        // Spring MVC calls method loadPetWithVisit(...) before initNewVisitForm is called
        @GetMapping("/owners/*/pets/{petId}/visits/new")
        public String initNewVisitForm(@PathVariable("petId") int petId, Map<String, Object> model) {
            return "pets/createOrUpdateVisitForm";
        }

        // Spring MVC calls method loadPetWithVisit(...) before processNewVisitForm is called
        @PostMapping("/owners/{ownerId}/pets/{petId}/visits/new")
        public String processNewVisitForm(@Valid Visit visit, BindingResult result) {
            if (result.hasErrors()) {
                return "pets/createOrUpdateVisitForm";
            } else {
                this.visits.save(visit);
                return "redirect:/owners/{ownerId}";
            }
        }

    }