{"id":5853,"date":"2022-07-25T21:28:57","date_gmt":"2022-07-25T12:28:57","guid":{"rendered":"https:\/\/www.skyer9.pe.kr\/wordpress\/?p=5853"},"modified":"2025-07-03T16:48:33","modified_gmt":"2025-07-03T07:48:33","slug":"projections-%ec%9d%98-%ea%b0%9d%ec%b2%b4-%ec%83%9d%ec%84%b1%eb%b0%a9%eb%b2%95-3%ea%b0%80%ec%a7%80","status":"publish","type":"post","link":"https:\/\/www.skyer9.pe.kr\/wordpress\/?p=5853","title":{"rendered":"Projections \uc758 \uac1d\uccb4 \uc0dd\uc131\ubc29\ubc95 4\uac00\uc9c0"},"content":{"rendered":"

Projections \uc758 \uac1d\uccb4 \uc0dd\uc131\ubc29\ubc95 4\uac00\uc9c0<\/h1>\n

Projections \uc0ac\uc6a9\ubc95\uc5d0 \ub300\ud574 \uc624\ud574\ub97c \ubd88\ub7ec\uc62c \uc218 \uc788\ub2e4\ub294 \uc758\uacac\uc774 \uc788\uc5b4 \ubb38\uc11c \ucd94\uac00\uc791\uc131\ud569\ub2c8\ub2e4.<\/p>\n

Projections.bean()<\/h2>\n

\uae30\ubcf8 \uc0dd\uc131\uc790(@NoArgsConstructor) + @Setter \ub97c \uc774\uc6a9\ud574 \uac1d\uccb4\ub97c \uc0dd\uc131\ud569\ub2c8\ub2e4.<\/p>\n

\uc9c1\uad00\uc801\uc774\uace0 \uc774\ud574\ud558\uae30 \uc27d\uc2b5\ub2c8\ub2e4.
\n\uc57d\uac04\uc758 \uc131\ub2a5 \uc624\ubc84\ud5e4\ub4dc\uac00 \uc788\uc2b5\ub2c8\ub2e4.<\/p>\n

@Setter \uac00 \ud544\uc218\uc774\ubbc0\ub85c, \ubd88\ubcc0\uac1d\uccb4\uac00 \ub420 \uc218 \uc5c6\uc2b5\ub2c8\ub2e4.<\/p>\n

@Getter\n@Setter\n@NoArgsConstructor\n@AllArgsConstructor(access = AccessLevel.PROTECTED)\npublic class UserGroupByDto {\n    private String username;\n    private Long count;\n}<\/code><\/pre>\n
    public List<UserGroupByDto> groupBy() {\n\n        return jpaQueryFactory\n                .select(\n                        Projections.bean(\n                                UserGroupByDto.class\n                                , user.username\n                                , user.count().as("count")\n                        )\n                )\n                .from(user)\n                .groupBy(user.username)\n                .orderBy(user.username.asc())\n                .fetch();\n    }<\/code><\/pre>\n
Projections.fields()<\/h2>\n
@Setter \ub97c \uc0ac\uc6a9\ud558\uc9c0 \uc54a\uace0 \uac1d\uccb4\uc5d0 \ub370\uc774\ud0c0\ub97c \uc9c1\uc811 \uc785\ub825\ud569\ub2c8\ub2e4.
\n\uae30\ubcf8 \uc0dd\uc131\uc790(@NoArgsConstructor) \uac00 \ud544\uc694\ud569\ub2c8\ub2e4.<\/p>\n
@Getter\n@NoArgsConstructor\npublic class UserGroupByDto {\n\n    private String username;\n    private Long count;\n\n    private UserGroupByDto(String username, Long count) {\n        throw new RuntimeException("Projections \uc744 \uc774\uc6a9\ud574 \uac1d\uccb4 \uc0dd\uc131\ud560 \uac83");\n    }\n}<\/code><\/pre>\n
    public List<UserGroupByDto> groupBy() {\n\n        return jpaQueryFactory\n                .select(\n                        Projections.fields(\n                                UserGroupByDto.class\n                                , user.username\n                                , user.count().as("count")\n                        )\n                )\n                .from(user)\n                .groupBy(user.username)\n                .orderBy(user.username.asc())\n                .fetch();\n    }<\/code><\/pre>\n
Projections.constructor()<\/h2>\n
\uc0dd\uc131\uc790\ub97c \uc774\uc6a9\ud574 \uac1d\uccb4\ub97c \uc0dd\uc131\ud569\ub2c8\ub2e4.
\n@AllArgsConstructor \uac00 \ud544\uc218\uc774\uace0, @Setter \ub294 \ud544\uc694\uc5c6\uc2b5\ub2c8\ub2e4.
\n\uc131\ub2a5\uc774 \uc88b\uc2b5\ub2c8\ub2e4.
\n\ubcc0\uc218\uba85 \uae30\ubc18 \ub9e4\uce6d\uc774 \uc544\ub2c8\ub77c \uc21c\uc11c\uae30\ubc18 \ub9e4\uce6d\uc73c\ub85c \uc0dd\uc131\uc790\uc640 \uc21c\uc11c\ub97c \uc77c\uce58\uc2dc\ucf1c\uc57c \ud569\ub2c8\ub2e4.<\/p>\n
@Getter\n@AllArgsConstructor\npublic class UserGroupByDto {\n\n    private String username;\n    private Long count;\n}<\/code><\/pre>\n
List<UserGroupByDto> users = queryFactory\n    .select(Projections.constructor(UserGroupByDto.class,\n        user.username,\n        user.count))\n    .from(user)\n    .fetch();<\/code><\/pre>\n
@QueryProjection<\/h2>\n
@QueryProjection \uc744 \uc9c0\uc815\ud574\uc11c DTO \ub3c4 QClass \ub97c \uc0dd\uc131\ud558\ub3c4\ub85d \ud558\uace0,
\n\uc0dd\uc131\ub41c QClass \ub97c \uc774\uc6a9\ud558\ub294 \ubc29\uc2dd\uc785\ub2c8\ub2e4.
\nDTO \ub3c4 QClass \ub97c \uc0dd\uc131\ud558\uac8c \ub418\uc9c0\ub9cc, \ucef4\ud30c\uc77c \ud0c0\uc784 \uc624\ub958\uccb4\ud06c\ub97c \ud560 \uc218 \uc788\uace0 \uc131\ub2a5\uc774 \uc88b\uc2b5\ub2c8\ub2e4.<\/p>\n
@QueryProjection<\/code> \ub97c \uc0ac\uc6a9\ud558\ubbc0\ub85c, Querydsl\uc758 \uc758\uc874\uc131\uc774 \ud544\uc694 \uc5c6\ub294 \ub808\uc774\uc5b4\uc5d0\uc11c\ub3c4 \ud574\ub2f9 \uc758\uc874\uc131\uc774 \ud544\uc694\ud558\uac8c \ub429\ub2c8\ub2e4.<\/p>\n
@Getter\n@Setter\n@NoArgsConstructor\npublic class UserGroupByDto {\n\n    private String username;\n    private Long count;\n\n    @QueryProjection\n    public UserGroupByDto(String username, Long count) {\n        this.username = username;\n        this.count = count;\n    }\n}<\/code><\/pre>\n
    public List<UserGroupByDto> groupBy() {\n\n        return jpaQueryFactory\n                .select(new QUserGroupByDto(\n                                user.username\n                                , user.count().as("count")\n                        )\n                )\n                .from(user)\n                .groupBy(user.username)\n                .orderBy(user.username.asc())\n                .fetch();\n    }<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
Projections \uc758 \uac1d\uccb4 \uc0dd\uc131\ubc29\ubc95 4\uac00\uc9c0 Projections \uc0ac\uc6a9\ubc95\uc5d0 \ub300\ud574 \uc624\ud574\ub97c \ubd88\ub7ec\uc62c \uc218 \uc788\ub2e4\ub294 \uc758\uacac\uc774 \uc788\uc5b4 \ubb38\uc11c \ucd94\uac00\uc791\uc131\ud569\ub2c8\ub2e4. Projections.bean() \uae30\ubcf8 \uc0dd\uc131\uc790(@NoArgsConstructor) + @Setter \ub97c \uc774\uc6a9\ud574 \uac1d\uccb4\ub97c \uc0dd\uc131\ud569\ub2c8\ub2e4. \uc9c1\uad00\uc801\uc774\uace0 \uc774\ud574\ud558\uae30 \uc27d\uc2b5\ub2c8\ub2e4. \uc57d\uac04\uc758 \uc131\ub2a5 \uc624\ubc84\ud5e4\ub4dc\uac00 \uc788\uc2b5\ub2c8\ub2e4. @Setter \uac00 \ud544\uc218\uc774\ubbc0\ub85c, \ubd88\ubcc0\uac1d\uccb4\uac00 \ub420 \uc218 \uc5c6\uc2b5\ub2c8\ub2e4. @Getter @Setter @NoArgsConstructor @AllArgsConstructor(access = AccessLevel.PROTECTED) public class UserGroupByDto { private String username; private Long count;\u2026 Read More »<\/a><\/span><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[29],"tags":[],"class_list":["post-5853","post","type-post","status-publish","format-standard","hentry","category-spring-boot-2-5"],"_links":{"self":[{"href":"https:\/\/www.skyer9.pe.kr\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/5853","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.skyer9.pe.kr\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.skyer9.pe.kr\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.skyer9.pe.kr\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.skyer9.pe.kr\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5853"}],"version-history":[{"count":11,"href":"https:\/\/www.skyer9.pe.kr\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/5853\/revisions"}],"predecessor-version":[{"id":10462,"href":"https:\/\/www.skyer9.pe.kr\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/5853\/revisions\/10462"}],"wp:attachment":[{"href":"https:\/\/www.skyer9.pe.kr\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5853"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.skyer9.pe.kr\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5853"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.skyer9.pe.kr\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5853"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}