Add slug updates.

Updates of the title of a banner will change the canonical slug of the banner. A banner can be addressed by all previous slugs.
bannergress · Aug 9, 2021 · 1fda0cf · 1fda0cf
1 parent 99aedd5
commit 1fda0cf
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Showing 14 changed files with 106 additions and 36 deletions.
diff --git a/src/main/java/com/bannergress/backend/controllers/BannerController.java b/src/main/java/com/bannergress/backend/controllers/BannerController.java
@@ -200,7 +200,7 @@ public void postSettings(@PathVariable final String id, @Valid @RequestBody Bann
 
     private BannerDto toSummary(Banner banner) {
         BannerDto dto = new BannerDto();
-        dto.id = banner.getSlug();
+        dto.id = banner.getCanonicalSlug();
         dto.title = banner.getTitle();
         dto.numberOfMissions = banner.getNumberOfMissions();
         dto.lengthMeters = banner.getLengthMeters();
@@ -230,7 +230,7 @@ private void amendUserSettings(Principal principal, Collection<BannerDto> banner
             List<BannerSettings> bannerSettings = bannerSettingsService.getBannerSettings(principal.getName(),
                 bannerDtos.stream().map(b -> b.id).collect(Collectors.toList()));
             Map<String, BannerListType> bannerListTypes = bannerSettings.stream()
-                .collect(Collectors.toMap(s -> s.getBanner().getSlug(), s -> s.getListType()));
+                .collect(Collectors.toMap(s -> s.getBanner().getCanonicalSlug(), s -> s.getListType()));
             for (BannerDto bannerDto : bannerDtos) {
                 BannerListType listType = bannerListTypes.get(bannerDto.id);
                 bannerDto.listType = listType == BannerListType.none ? null : listType;

diff --git a/src/main/java/com/bannergress/backend/controllers/MetaController.java b/src/main/java/com/bannergress/backend/controllers/MetaController.java
@@ -52,7 +52,7 @@ public String getBannerMeta(@PathVariable String id) {
             String distance = getDistance(banner);
             String place = getPlaceName(banner);
             String description = String.format("%s Missions, %s\n%s", banner.getNumberOfMissions(), distance, place);
-            String url = siteUrls.getBannerUrl(banner.getSlug());
+            String url = siteUrls.getBannerUrl(banner.getCanonicalSlug());
             String pictureUrl = banner.getPicture() == null ? null
                 : siteUrls.getPictureUrl(banner.getPicture().getHash());
             return new MetaBuilder() //

diff --git a/src/main/java/com/bannergress/backend/entities/Banner.java b/src/main/java/com/bannergress/backend/entities/Banner.java
@@ -34,12 +34,21 @@ public class Banner {
     private UUID uuid;
 
     /**
-     * Slug (ID which is suitable for use in URLs).
+     * Canonical slug (ID which is suitable for use in URLs).
      */
-    @NaturalId
+    @NaturalId(mutable = true)
+    @Column(name = "canonical_slug", nullable = false)
+    @NotAudited
+    private String canonicalSlug;
+
+    /**
+     * All slugs, including the {@link #canonicalSlug}.
+     */
+    @ElementCollection(fetch = FetchType.LAZY)
+    @CollectionTable(name = "banner_slug", joinColumns = @JoinColumn(name = "banner"))
     @Column(name = "slug", nullable = false)
     @NotAudited
-    private String slug;
+    private Set<String> slugs = new HashSet<>();
 
     /**
      * Title.
@@ -153,12 +162,20 @@ public void setUuid(UUID uuid) {
         this.uuid = uuid;
     }
 
-    public String getSlug() {
-        return slug;
+    public String getCanonicalSlug() {
+        return canonicalSlug;
+    }
+
+    public void setCanonicalSlug(String canonicalSlug) {
+        this.canonicalSlug = canonicalSlug;
+    }
+
+    public Set<String> getSlugs() {
+        return slugs;
     }
 
-    public void setSlug(String slug) {
-        this.slug = slug;
+    public void setSlugs(Set<String> slugs) {
+        this.slugs = slugs;
     }
 
     public String getTitle() {
@@ -279,12 +296,13 @@ public boolean equals(final Object o) {
             && Objects.equals(description, banner.description) && Objects.equals(missions, banner.missions)
             && Objects.equals(startPoint, banner.startPoint) && Objects.equals(lengthMeters, banner.lengthMeters)
             && Objects.equals(picture, banner.picture) && Objects.equals(startPlaces, banner.startPlaces)
-            && Objects.equals(created, banner.created) && type == banner.type && Objects.equals(slug, banner.slug);
+            && Objects.equals(created, banner.created) && type == banner.type
+            && Objects.equals(canonicalSlug, banner.canonicalSlug);
     }
 
     @Override
     public int hashCode() {
         return Objects.hash(uuid, title, description, numberOfMissions, missions, startPoint, lengthMeters, complete,
-            online, picture, startPlaces, created, type, slug);
+            online, picture, startPlaces, created, type, canonicalSlug);
     }
 }
diff --git a/src/main/java/com/bannergress/backend/repositories/BannerRepository.java b/src/main/java/com/bannergress/backend/repositories/BannerRepository.java
@@ -18,8 +18,8 @@ public interface BannerRepository extends JpaRepository<Banner, UUID>, JpaSpecif
     @Query("SELECT b.uuid FROM Banner b")
     List<UUID> getAllUUIDs();
 
-    @Query("SELECT b.slug FROM Banner b")
+    @Query("SELECT b.canonicalSlug FROM Banner b")
     List<String> getAllSlugs();
 
-    Optional<Banner> findBySlug(String slug);
+    Optional<Banner> findByCanonicalSlug(String slug);
 }
diff --git a/src/main/java/com/bannergress/backend/repositories/BannerSettingsRepository.java b/src/main/java/com/bannergress/backend/repositories/BannerSettingsRepository.java
@@ -14,7 +14,7 @@
  */
 @Repository
 public interface BannerSettingsRepository extends JpaRepository<BannerSettings, UUID> {
-    Optional<BannerSettings> findByUserIdAndBannerSlug(String userId, String bannerSlug);
+    Optional<BannerSettings> findByUserIdAndBannerCanonicalSlug(String userId, String bannerSlug);
 
-    List<BannerSettings> findByUserIdAndBannerSlugIn(String userId, Collection<String> bannerSlugs);
+    List<BannerSettings> findByUserIdAndBannerCanonicalSlugIn(String userId, Collection<String> bannerSlugs);
 }
diff --git a/src/main/java/com/bannergress/backend/repositories/BannerSpecifications.java b/src/main/java/com/bannergress/backend/repositories/BannerSpecifications.java
@@ -55,7 +55,10 @@ public static Specification<Banner> hasMissionId(String missionId) {
     }
 
     public static Specification<Banner> hasSlug(String slug) {
-        return (banner, cq, cb) -> cb.equal(banner.get(Banner_.slug), slug);
+        return (banner, cq, cb) -> {
+            Join<Banner, String> slugs = banner.join(Banner_.slugs);
+            return cb.equal(slugs, slug);
+        };
     }
 
     public static Specification<Banner> hasStartPlaceSlug(String startPlaceSlug) {

diff --git a/src/main/java/com/bannergress/backend/services/BannerSettingsService.java b/src/main/java/com/bannergress/backend/services/BannerSettingsService.java
@@ -22,7 +22,7 @@ public interface BannerSettingsService {
      * Retrieves banner settings user and a collection of banners.
      *
      * @param userId  ID of the user.
-     * @param banners Slugs of banner for which to retrieve the settings.
+     * @param banners Canonical slugs of banner for which to retrieve the settings.
      * @return Banner settings.
      */
     List<BannerSettings> getBannerSettings(String userId, Collection<String> bannerSlugs);

diff --git a/src/main/java/com/bannergress/backend/services/impl/BannerServiceImpl.java b/src/main/java/com/bannergress/backend/services/impl/BannerServiceImpl.java
@@ -36,6 +36,7 @@
 
 import java.time.Instant;
 import java.util.*;
+import java.util.stream.Stream;
 
 /**
  * Default implementation of {@link BannerService}.
@@ -173,10 +174,20 @@ public Optional<Banner> findBySlugWithDetails(String slug) {
     @Override
     public String create(BannerDto bannerDto) throws MissionAlreadyUsedException {
         Banner banner = createTransient(bannerDto, List.of());
-        banner.setSlug(deriveSlug(banner));
+        calculateSlug(banner);
         bannerRepository.save(banner);
         banner.getStartPlaces().forEach(place -> place.setNumberOfBanners(place.getNumberOfBanners() + 1));
-        return banner.getSlug();
+        return banner.getCanonicalSlug();
+    }
+
+    private void calculateSlug(Banner banner) {
+        // Slug candidates: 1. current canonical slug 2. any previous slug 3. new slug
+        Stream<String> slugCandidates = Stream.concat(
+            Stream.concat(Optional.ofNullable(banner.getCanonicalSlug()).stream(), banner.getSlugs().stream()),
+            Stream.generate(() -> deriveSlug(banner)));
+        String slug = slugCandidates.filter(s -> slugGenerator.isDerivedFrom(s, banner.getTitle())).findFirst().get();
+        banner.setCanonicalSlug(slug);
+        banner.getSlugs().add(slug);
     }
 
     private String deriveSlug(Banner banner) {
@@ -224,6 +235,7 @@ public void update(String slug, BannerDto bannerDto) throws MissionAlreadyUsedEx
         banner.getMissions().clear();
         banner.getMissions()
             .putAll(Maps.transformValues(bannerDto.missions, missionDto -> missionRepository.getOne(missionDto.id)));
+        calculateSlug(banner);
         bannerService.calculateData(banner);
         pictureService.refresh(banner);
     }

diff --git a/src/main/java/com/bannergress/backend/services/impl/BannerSettingsServiceImpl.java b/src/main/java/com/bannergress/backend/services/impl/BannerSettingsServiceImpl.java
@@ -37,16 +37,16 @@ public void addBannerToList(String userId, String bannerSlug, BannerListType lis
 
     @Override
     public List<BannerSettings> getBannerSettings(String userId, Collection<String> bannerSlugs) {
-        return bannerSettingsRepository.findByUserIdAndBannerSlugIn(userId, bannerSlugs);
+        return bannerSettingsRepository.findByUserIdAndBannerCanonicalSlugIn(userId, bannerSlugs);
     }
 
     private BannerSettings getOrCreate(String userId, String bannerSlug) {
-        Optional<BannerSettings> optionalBannerSettings = bannerSettingsRepository.findByUserIdAndBannerSlug(userId,
-            bannerSlug);
+        Optional<BannerSettings> optionalBannerSettings = bannerSettingsRepository
+            .findByUserIdAndBannerCanonicalSlug(userId, bannerSlug);
         return optionalBannerSettings.orElseGet(() -> {
             BannerSettings bannerSettings = new BannerSettings();
             bannerSettings.setUser(userService.getOrCreate(userId));
-            bannerSettings.setBanner(bannerRepository.findBySlug(bannerSlug).get());
+            bannerSettings.setBanner(bannerRepository.findByCanonicalSlug(bannerSlug).get());
             return bannerSettingsRepository.save(bannerSettings);
         });
     }

diff --git a/src/main/java/com/bannergress/backend/services/impl/MissionServiceImpl.java b/src/main/java/com/bannergress/backend/services/impl/MissionServiceImpl.java
@@ -63,7 +63,7 @@ public Collection<Mission> findByIds(Collection<String> ids) {
     public void assertNotAlreadyUsedInBanners(Collection<String> ids, List<String> acceptableBannerSlugs)
         throws MissionAlreadyUsedException {
         String acceptableBannerSlugsPart = acceptableBannerSlugs.isEmpty() ? ""
-            : " AND b.slug NOT IN :acceptableBannerSlugs";
+            : " AND b.canonicalSlug NOT IN :acceptableBannerSlugs";
         TypedQuery<Long> query = entityManager.createQuery("SELECT COUNT(m) FROM Mission m WHERE m.id IN :ids "
             + "AND NOT EXISTS (SELECT 1 FROM Banner b WHERE b MEMBER OF m.banners" + acceptableBannerSlugsPart + ")",
             Long.class);

diff --git a/src/main/java/com/bannergress/backend/utils/SlugGenerator.java b/src/main/java/com/bannergress/backend/utils/SlugGenerator.java
@@ -35,9 +35,7 @@ public SlugGenerator(int suffixBytes) {
      * @return Slug.
      */
     public String generateSlug(String base, Predicate<String> isAvailable) {
-        String lowerCase = base.toLowerCase(Locale.ROOT);
-        String onlyAlphanum = replacedCharacters.matcher(lowerCase).replaceAll("-");
-        String prefix = onlyAlphanum.replaceAll("^-+|-+$", "");
+        String prefix = getPrefix(base);
         while (true) {
             byte[] random = new byte[suffixBytes];
             numberGenerator.nextBytes(random);
@@ -47,4 +45,28 @@ public String generateSlug(String base, Predicate<String> isAvailable) {
             }
         }
     }
+
+    private String getPrefix(String base) {
+        String lowerCase = base.toLowerCase(Locale.ROOT);
+        String onlyAlphanum = replacedCharacters.matcher(lowerCase).replaceAll("-");
+        String prefix = onlyAlphanum.replaceAll("^-+|-+$", "");
+        return prefix;
+    }
+
+    /**
+     * Checks whether a slug is derived from a base string.
+     *
+     * @param slug Slug.
+     * @param base Base string.
+     * @return <code>true</code> whether the slug is derived from the base string.
+     */
+    public boolean isDerivedFrom(String slug, String base) {
+        String prefix = getPrefix(base);
+        if (slug.startsWith(prefix)) {
+            String remainder = slug.substring(prefix.length());
+            return remainder.matches("^-[0-9a-f]+$");
+        } else {
+            return false;
+        }
+    }
 }
diff --git a/src/main/resources/db/migration/V2_12__slugs.sql b/src/main/resources/db/migration/V2_12__slugs.sql
@@ -0,0 +1,11 @@
+CREATE TABLE "banner_slug" (
+  "slug" text NOT NULL,
+  "banner" "uuid" NOT NULL,
+  PRIMARY KEY ("slug"),
+  UNIQUE ("banner", "slug"),
+  FOREIGN KEY ("banner") REFERENCES "banner"("uuid")
+);
+INSERT INTO "banner_slug" ("slug", "banner") SELECT "slug", "uuid" FROM "banner";
+
+ALTER TABLE "banner" RENAME COLUMN "slug" TO "canonical_slug";
+ALTER TABLE "banner" ADD FOREIGN KEY ("uuid", "canonical_slug") REFERENCES "banner_slug" ("banner", "slug") DEFERRABLE INITIALLY DEFERRED;
diff --git a/src/test/java/com/bannergress/backend/controllers/BannerControllerTest.java b/src/test/java/com/bannergress/backend/controllers/BannerControllerTest.java
@@ -53,7 +53,7 @@ void list() {
         assertThat(result.getStatusCode()).isEqualTo(HttpStatus.OK);
         assertThat(result.getBody()).hasSize(1);
         final var bannerDto = result.getBody().get(0);
-        assertThat(bannerDto.id).isEqualTo(banner.getSlug());
+        assertThat(bannerDto.id).isEqualTo(banner.getCanonicalSlug());
         assertThat(bannerDto.numberOfMissions).isEqualTo(banner.getNumberOfMissions());
         assertThat(bannerDto.lengthMeters).isEqualTo(banner.getLengthMeters());
     }
@@ -86,7 +86,7 @@ void list_withBoundingBox() {
         assertThat(result.getStatusCode()).isEqualTo(HttpStatus.OK);
         assertThat(result.getBody()).hasSize(1);
         final var bannerDto = result.getBody().get(0);
-        assertThat(bannerDto.id).isEqualTo(banner.getSlug());
+        assertThat(bannerDto.id).isEqualTo(banner.getCanonicalSlug());
         assertThat(bannerDto.numberOfMissions).isEqualTo(banner.getNumberOfMissions());
         assertThat(bannerDto.lengthMeters).isEqualTo(banner.getLengthMeters());
     }
@@ -106,7 +106,7 @@ void get() {
         assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
         final BannerDto bannerDto = response.getBody();
         assertThat(bannerDto).isNotNull();
-        assertThat(bannerDto.id).isEqualTo(banner.getSlug());
+        assertThat(bannerDto.id).isEqualTo(banner.getCanonicalSlug());
         assertThat(bannerDto.numberOfMissions).isEqualTo(banner.getNumberOfMissions());
         assertThat(bannerDto.lengthMeters).isEqualTo(banner.getLengthMeters());
         assertThat(bannerDto.type).isEqualTo(banner.getType());
@@ -133,8 +133,8 @@ void post() throws MissionAlreadyUsedException {
         final BannerDto banner = a($BannerDto());
         final Banner savedBanner = fixPlaceInformation(a($Banner()));
 
-        when(bannerService.create(banner)).thenReturn(savedBanner.getSlug());
-        when(bannerService.findBySlugWithDetails(savedBanner.getSlug())).thenReturn(Optional.of(savedBanner));
+        when(bannerService.create(banner)).thenReturn(savedBanner.getCanonicalSlug());
+        when(bannerService.findBySlugWithDetails(savedBanner.getCanonicalSlug())).thenReturn(Optional.of(savedBanner));
 
         // THEN
         final var response = testController.post(banner, null);
@@ -143,7 +143,7 @@ void post() throws MissionAlreadyUsedException {
         assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
         final BannerDto bannerDto = response.getBody();
         assertThat(bannerDto).isNotNull();
-        assertThat(bannerDto.id).isEqualTo(savedBanner.getSlug());
+        assertThat(bannerDto.id).isEqualTo(savedBanner.getCanonicalSlug());
         assertThat(bannerDto.numberOfMissions).isEqualTo(savedBanner.getNumberOfMissions());
         assertThat(bannerDto.lengthMeters).isEqualTo(savedBanner.getLengthMeters());
         assertThat(bannerDto.type).isEqualTo(savedBanner.getType());

diff --git a/src/test/java/com/bannergress/backend/utils/TestSlugGenerator.java b/src/test/java/com/bannergress/backend/utils/TestSlugGenerator.java
@@ -13,11 +13,15 @@ class TestSlugGenerator {
     void testReplacements() {
         SlugGenerator generator = new SlugGenerator(2);
 
-        String actual1 = generator.generateSlug("[Augsburg ist schön seit 15 v. Chr.]", Predicates.alwaysTrue());
+        String base1 = "[Augsburg ist schön seit 15 v. Chr.]";
+        String actual1 = generator.generateSlug(base1, Predicates.alwaysTrue());
         assertThat(actual1).matches("^augsburg-ist-schön-seit-15-v-chr-[0-9a-f]{4}$");
+        assertThat(generator.isDerivedFrom(actual1, base1));
 
-        String actual2 = generator.generateSlug("Волковское кладбище", Predicates.alwaysTrue());
+        String base2 = "Волковское кладбище";
+        String actual2 = generator.generateSlug(base2, Predicates.alwaysTrue());
         assertThat(actual2).matches("^волковское-кладбище-[0-9a-f]{4}$");
+        assertThat(generator.isDerivedFrom(actual2, base2));
     }
 
     @Test