Enum Eşleme — Bloklu Kart Neden Bir Gün Dondurulmuş Göründü?

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public enum CardStatus {
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    ACTIVE("A"),
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    FROZEN("F"),
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    SUSPENDED("B"), // renamed from BLOCKED; the stored code did not change
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    CLOSED("C");
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    private final String code;
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    CardStatus(String code) {
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        this.code = code;
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    }
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    public String code() {
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        return code;
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    }
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    public static CardStatus fromCode(String code) {
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        for (CardStatus status : values()) {
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            if (status.code.equals(code)) {
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                return status;
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            }
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        }
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        throw new IllegalArgumentException("Unknown card status code: " + code);
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    }
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}

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@Converter
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public class CardStatusConverter implements AttributeConverter<CardStatus, String> {
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    @Override
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    public String convertToDatabaseColumn(CardStatus status) {
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        return status == null ? null : status.code();
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    }
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    @Override
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    public CardStatus convertToEntityAttribute(String code) {
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        return code == null ? null : CardStatus.fromCode(code);
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    }
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}

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@Entity
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@Table(name = "cards")
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public class Card {
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    @Id
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    private UUID id;
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    @Column(name = "masked_pan", nullable = false)
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    private String maskedPan;
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    // Not @Enumerated: the column holds a fixed code, independent of name and order.
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    @Convert(converter = CardStatusConverter.class)
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    @Column(name = "status", length = 1, nullable = false)
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    private CardStatus status;
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    protected Card() {
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    }
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    public void freeze() {
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        if (status != CardStatus.ACTIVE) {
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            throw new IllegalStateException("Only an active card can be frozen");
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        }
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        status = CardStatus.FROZEN;
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    }
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}

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-- The column used to hold ordinals: 0 ACTIVE, 1 BLOCKED, 2 CLOSED.
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ALTER TABLE cards ADD COLUMN status_code CHAR(1);
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UPDATE cards SET status_code = CASE status
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    WHEN 0 THEN 'A'
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    WHEN 1 THEN 'B'
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    WHEN 2 THEN 'C'
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END;
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ALTER TABLE cards ALTER COLUMN status_code SET NOT NULL;
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ALTER TABLE cards DROP COLUMN status;
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ALTER TABLE cards RENAME COLUMN status_code TO status;

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class CardStatusTest {
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    @Test
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    void every_status_has_its_own_code() {
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        Set<String> codes = Arrays.stream(CardStatus.values())
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                .map(CardStatus::code)
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                .collect(Collectors.toSet());
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        assertThat(codes).hasSize(CardStatus.values().length);
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    }
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    @Test
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    void a_stored_code_reads_back_as_the_same_status() {
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        for (CardStatus status : CardStatus.values()) {
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            assertThat(CardStatus.fromCode(status.code())).isEqualTo(status);
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        }
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    }
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}