FC-238 remove cardHistories from Card to avoid cyclic dependency

backend/src/main/java/com/example/flashcards_backend/controller/CardController.java

@@ -50,9 +50,9 @@ public class CardController {
       content =
           @Content(
               mediaType = "application/json",
-              schema = @Schema(implementation = CardResponse[].class)))
+              schema = @Schema(implementation = CardSummary[].class)))
   @GetMapping
-  public ResponseEntity<List<CardResponse>> getAllCardResponses(
+  public ResponseEntity<List<CardSummary>> getAllCardResponses(
       @RequestParam Long subjectId, @AuthenticationPrincipal Jwt jwt) {
     log.info("GET /cards: subjectId={}", subjectId);
     User user = currentUserService.getCurrentUser(jwt);
@@ -71,13 +71,13 @@ public ResponseEntity<List<CardResponse>> getAllCardResponses(
       content =
           @Content(
               mediaType = "application/json",
-              schema = @Schema(implementation = CardResponse.class)))
+              schema = @Schema(implementation = CardSummary.class)))
   @ApiResponse(
       responseCode = "404",
       description = "Card not found",
       content = @Content(mediaType = "application/json"))
   @GetMapping("/{id}")
-  public ResponseEntity<CardResponse> getById(
+  public ResponseEntity<CardSummary> getById(
       @PathVariable Long id, @AuthenticationPrincipal Jwt jwt) {
     currentUserService.getCurrentUser(jwt);
     return ResponseEntity.ok(
@@ -134,8 +134,8 @@ public ResponseEntity<CardResponse> update(
       @Valid @RequestBody CardRequest request,
       @AuthenticationPrincipal Jwt jwt) {
     currentUserService.getCurrentUser(jwt);
-    CardResponse cardResponse = cardService.updateCard(id, request);
-    return ResponseEntity.ok(cardResponse);
+    CardResponse response = cardService.updateCard(id, request);
+    return ResponseEntity.ok(response);
   }
 
   @Operation(summary = "Rate card", description = "Rates a card by its ID.")

backend/src/main/java/com/example/flashcards_backend/dto/CardResponse.java

@@ -1,85 +1,31 @@
 package com.example.flashcards_backend.dto;
 
 import com.example.flashcards_backend.model.Card;
-import com.example.flashcards_backend.model.CardHistory;
-
-import java.util.HashSet;
+import com.fasterxml.jackson.annotation.JsonProperty;
 import java.util.Set;
 import java.util.stream.Collectors;
 
-import com.example.flashcards_backend.repository.CardDeckRowProjection;
-import com.fasterxml.jackson.annotation.JsonCreator;
-import com.fasterxml.jackson.annotation.JsonProperty;
-import lombok.Builder;
-
-@Builder
 public record CardResponse(
-        @JsonProperty("id") Long id,
-        @JsonProperty("front") String front,
-        @JsonProperty("back") String back,
-        @JsonProperty("hintFront") String hintFront,
-        @JsonProperty("hintBack") String hintBack,
-        @JsonProperty("decks") Set<DeckSummary> decks,
-        @JsonProperty("avgRating") Double avgRating,
-        @JsonProperty("viewCount") Integer viewCount,
-        @JsonProperty("lastViewed") String lastViewed,
-        @JsonProperty("lastRating") Integer lastRating,
-        @JsonProperty("subjectId") Long subjectId
-) {
-
-    @JsonCreator
-    public CardResponse {
-        // canonical constructor; Jackson will call this
-    }
-
-    public static CardResponse fromEntity(Card card) {
-        Set<DeckSummary> deckSummaries = card.getDecks().stream()
-                .map(DeckSummary::fromEntity)
-                .collect(Collectors.toSet());
-
-        CardHistory ch = card.getCardHistories().stream()
-                .findFirst()
-                .orElseGet(CardHistory::new);
-
-        return new CardResponse(
-                card.getId(),
-                card.getFront(),
-                card.getBack(),
-                card.getHintFront(),
-                card.getHintBack(),
-                deckSummaries,
-                ch.getAvgRating(),
-                ch.getViewCount(),
-                ch.getLastViewed() != null ? ch.getLastViewed().toString() : null,
-                ch.getLastRating(),
-                card.getSubject().getId()
-        );
-    }
-
-    public static CardResponse fromEntity(CardDeckRowProjection cd) {
-        return new CardResponse(
-                cd.getCardId(),
-                cd.getFront(),
-                cd.getBack(),
-                cd.getHintFront(),
-                cd.getHintBack(),
-                new HashSet<>(),
-                cd.getAvgRating(),
-                cd.getViewCount(),
-                cd.getLastViewed() != null ? cd.getLastViewed().toString() : null,
-                cd.getLastRating(),
-                cd.getSubjectId()
-        );
-    }
-
-    public static CardResponse fromEntity(CreateCardResponse ccr) {
-        return CardResponse.builder()
-                .id(ccr.id())
-                .front(ccr.front())
-                .back(ccr.back())
-                .hintFront(ccr.hintFront())
-                .hintBack(ccr.hintBack())
-                .decks(new HashSet<>(ccr.decks()))
-                .build();
-    }
-}
+    @JsonProperty("id") Long id,
+    @JsonProperty("front") String front,
+    @JsonProperty("back") String back,
+    @JsonProperty("hintFront") String hintFront,
+    @JsonProperty("hintBack") String hintBack,
+    @JsonProperty("decks") Set<DeckSummary> decks,
+    @JsonProperty("subjectId") Long subjectId) {
+  public static CardResponse fromEntity(Card card) {
+    Set<DeckSummary> deckSummaries = card.getDecks().stream()
+        .map(DeckSummary::fromEntity)
+        .collect(Collectors.toSet());
+
+    return new CardResponse(
+        card.getId(),
+        card.getFront(),
+        card.getBack(),
+        card.getHintFront(),
+        card.getHintBack(),
+        deckSummaries,
+        card.getSubject().getId()
+    );
+  }
+}

backend/src/main/java/com/example/flashcards_backend/dto/CardSummary.java

@@ -0,0 +1,81 @@
+package com.example.flashcards_backend.dto;
+
+import com.example.flashcards_backend.model.Card;
+import com.example.flashcards_backend.model.CardHistory;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import com.example.flashcards_backend.repository.CardDeckRowProjection;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import lombok.Builder;
+
+@Builder
+public record CardSummary(
+    @JsonProperty("id") Long id,
+    @JsonProperty("front") String front,
+    @JsonProperty("back") String back,
+    @JsonProperty("hintFront") String hintFront,
+    @JsonProperty("hintBack") String hintBack,
+    @JsonProperty("decks") Set<DeckSummary> decks,
+    @JsonProperty("avgRating") Double avgRating,
+    @JsonProperty("viewCount") Integer viewCount,
+    @JsonProperty("lastViewed") String lastViewed,
+    @JsonProperty("lastRating") Integer lastRating,
+    @JsonProperty("subjectId") Long subjectId) {
+
+  @JsonCreator
+  public CardSummary {
+    // canonical constructor; Jackson will call this
+  }
+
+  public static CardSummary fromEntity(Card card, CardHistory ch) {
+    Set<DeckSummary> deckSummaries =
+        card.getDecks().stream().map(DeckSummary::fromEntity).collect(Collectors.toSet());
+
+    if (ch == null) {
+      ch = CardHistory.builder().avgRating(0.0).viewCount(0).lastViewed(null).lastRating(0).build();
+    }
+
+    return new CardSummary(
+        card.getId(),
+        card.getFront(),
+        card.getBack(),
+        card.getHintFront(),
+        card.getHintBack(),
+        deckSummaries,
+        ch.getAvgRating(),
+        ch.getViewCount(),
+        ch.getLastViewed() != null ? ch.getLastViewed().toString() : null,
+        ch.getLastRating(),
+        card.getSubject().getId());
+  }
+
+  public static CardSummary fromEntity(CardDeckRowProjection cd) {
+    return new CardSummary(
+        cd.getCardId(),
+        cd.getFront(),
+        cd.getBack(),
+        cd.getHintFront(),
+        cd.getHintBack(),
+        new HashSet<>(),
+        cd.getAvgRating(),
+        cd.getViewCount(),
+        cd.getLastViewed() != null ? cd.getLastViewed().toString() : null,
+        cd.getLastRating(),
+        cd.getSubjectId());
+  }
+
+  public static CardSummary fromEntity(CreateCardResponse ccr) {
+    return CardSummary.builder()
+        .id(ccr.id())
+        .front(ccr.front())
+        .back(ccr.back())
+        .hintFront(ccr.hintFront())
+        .hintBack(ccr.hintBack())
+        .decks(new HashSet<>(ccr.decks()))
+        .build();
+  }
+}

backend/src/main/java/com/example/flashcards_backend/dto/CsvUploadResponseDto.java

@@ -5,4 +5,4 @@
 import java.util.List;
 
 @Builder
-public record CsvUploadResponseDto(List<CardResponse> saved, List<CardResponse> duplicates) {}
+public record CsvUploadResponseDto(List<CardSummary> saved, List<CardSummary> duplicates) {}

backend/src/main/java/com/example/flashcards_backend/dto/UserDto.java

@@ -5,9 +5,4 @@
 import java.util.UUID;
 
 @Builder
-public record UserDto(
-        String username,
-        UUID id,
-        boolean isActive
-) {
-}
+public record UserDto(String username, UUID id, boolean isActive) {}

backend/src/main/java/com/example/flashcards_backend/dto/UserStatsResponse.java

@@ -5,8 +5,8 @@
 @Builder
 public record UserStatsResponse(
         Long totalCards,
-        CardResponse hardestCard,
-        CardResponse mostViewedCard,
+        CardSummary hardestCard,
+        CardSummary mostViewedCard,
         Long totalCardViews,
         Long totalLastRating1,
         Long totalLastRating2,

backend/src/main/java/com/example/flashcards_backend/model/Card.java

@@ -17,7 +17,7 @@
 @Setter
 @RequiredArgsConstructor
 @AllArgsConstructor
-@Builder(builderClassName = "CardBuilder", toBuilder = true)
+@Builder(toBuilder = true)
 @Table(name = "card", uniqueConstraints = @UniqueConstraint(columnNames = {"front", "back"}))
 public class Card {
     @Id
@@ -53,12 +53,6 @@ public class Card {
     @NotNull
     private Subject subject;
 
-    @OneToMany(mappedBy = "card", cascade = CascadeType.REMOVE, orphanRemoval = true)
-    @EqualsAndHashCode.Exclude
-    @ToString.Exclude
-    @Singular
-    private final Set<CardHistory> cardHistories = new HashSet<>();
-
     @ManyToOne(fetch = FetchType.LAZY, optional = false)
     @JoinColumn(name = "user_id", nullable = false)
     private User user;
@@ -118,44 +112,6 @@ public Set<String> getDeckNames() {
         return deckNames;
     }
 
-    public void addCardHistory(CardHistory cardHistory) {
-        cardHistory.setCard(this);
-    }
-
-    @SuppressWarnings("unused")
-    public static class CardBuilder {
-        private Long id;
-        private String front;
-        private String back;
-        private String hintFront;
-        private String hintBack;
-        private Set<Deck> decks = new HashSet<>();
-        private Set<CardHistory> cardHistories = new HashSet<>();
-        private Subject subject;
-        private User user;
-
-        public CardBuilder cardHistory(CardHistory cardHistory) {
-            this.cardHistories.add(cardHistory);
-            return this;
-        }
-
-        public Card build() {
-            Card card = new Card();
-            card.id = this.id;
-            card.front = this.front;
-            card.back = this.back;
-            card.hintFront = this.hintFront;
-            card.hintBack = this.hintBack;
-            card.decks = this.decks;
-            card.subject = this.subject;
-            card.user = this.user;
-            for (CardHistory ch : this.cardHistories) {
-                card.addCardHistory(ch);
-            }
-            return card;
-        }
-    }
-
     @Override
     public final boolean equals(Object o) {
         if (this == o) return true;

backend/src/main/java/com/example/flashcards_backend/model/CardHistory.java

@@ -36,11 +36,4 @@ public class CardHistory extends BaseEntity {
   @ManyToOne(fetch = FetchType.LAZY, optional = false)
   @JoinColumn(name = "user_id", nullable = false)
   private User user;
-
-  public void setCard(Card card) {
-    this.card = card;
-    if (card != null) {
-      card.getCardHistories().add(this);
-    }
-  }
 }

backend/src/main/java/com/example/flashcards_backend/model/Subject.java

@@ -2,8 +2,6 @@
 
 import com.fasterxml.jackson.annotation.JsonBackReference;
 import jakarta.persistence.*;
-import java.util.HashSet;
-import java.util.Set;
 import lombok.AccessLevel;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
@@ -38,12 +36,6 @@ public class Subject extends BaseEntity {
   @Enumerated(EnumType.STRING)
   private CardOrder cardOrder;
 
-  @OneToMany(mappedBy = "subject", cascade = CascadeType.ALL, orphanRemoval = true)
-  private Set<Deck> decks = new HashSet<>();
-
-  @OneToMany(mappedBy = "subject", cascade = CascadeType.ALL, orphanRemoval = true)
-  private Set<Card> cards = new HashSet<>();
-
   @ManyToOne(fetch = FetchType.LAZY, optional = false)
   @JoinColumn(name = "user_id", nullable = false)
   @JsonBackReference