java - 无法将类型“java.lang.String”的值转换为所需类型
问题描述
我在 Spring-boot 2.2.1 上有 REST 服务器,使用 Spring-web 5.2.3 与 mysql 和 JavaFX 客户端连接。我想将http请求从客户端发送到服务器。对于方法 GET 效果很好,但对于 POST 效果不好。
我的实体:
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Entity(name = "CANDIDATES")
public class Candidate {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
private String lastname;
@Enumerated(EnumType.STRING)
private Education education;
private String placeOfResidence;
@ManyToMany(cascade = CascadeType.PERSIST)
@JoinTable(
name = "JOIN_VOTERESULTS_CANDIDATES",
joinColumns = {@JoinColumn(name = "CANDIDATES_ID", referencedColumnName = "ID")},
inverseJoinColumns = {@JoinColumn(name = "VOTERESULTS_ID",referencedColumnName = "ID")}
)
private List<VoteResult> voteResults;
@ManyToOne
@JoinColumn(name = "ELECTION_LISTS_ID")
private ElectionList electionList;
@ManyToOne
@JoinColumn(name = "ELECTORAL_PARTIES_ID")
private ElectoralParty electoralParty;
}
CandidateDto 具有相同的变量。这是我的 POST 控制器:
@PostMapping(value = "/createCandidate")
public void createCandidate(@Valid CandidateDto candidateDto) {
service.createCandidate(candidateDto);
}
这是在客户端创建此对象并将带有正文的 POST 请求发送到服务器的方法:
RestTemplate restTemplate = new RestTemplate();
restTemplate.setMessageConverters(getMessageConverters());
URI url = UriComponentsBuilder.fromHttpUrl(URL + "/createCandidate")
.queryParam("id", candidate.getId())
.queryParam("name", candidate.getName())
.queryParam("lastname", candidate.getLastname())
.queryParam("education", candidate.getEducation())
.queryParam("placeOfResidence", candidate.getPlaceOfResidence())
.queryParam("voteResults", candidate.getVoteResults())
.queryParam("electionList", candidate.getElectionList())
.queryParam("electoralParty", candidate.getElectoralParty()).build().encode().toUri();
restTemplate.postForObject(url, null, Candidate.class);
当我删除带有选举党、选举列表和投票结果的查询参数时,一切正常。但是使用这些参数,我在服务器中出现错误:
Field error in object 'candidateDto' on field 'education': rejected value [zawodowe]; codes [typeMismatch.candidateDto.education,typeMismatch.education,typeMismatch.com.pk.electionappserver.domain.Education,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [candidateDto.education,education]; arguments []; default message [education]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'com.pk.electionappserver.domain.Education' for property 'education'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [com.pk.electionappserver.domain.Education] for value 'zawodowe'; nested exception is java.lang.IllegalArgumentException: No enum constant com.pk.electionappserver.domain.Education.zawodowe]
Field error in object 'candidateDto' on field 'electionList': rejected value []; codes [typeMismatch.candidateDto.electionList,typeMismatch.electionList,typeMismatch.com.pk.electionappserver.domain.dto.ElectionListDto,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [candidateDto.electionList,electionList]; arguments []; default message [electionList]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'com.pk.electionappserver.domain.dto.ElectionListDto' for property 'electionList'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'com.pk.electionappserver.domain.dto.ElectionListDto' for property 'electionList': no matching editors or conversion strategy found]
Field error in object 'candidateDto' on field 'electoralParty': rejected value []; codes [typeMismatch.candidateDto.electoralParty,typeMismatch.electoralParty,typeMismatch.com.pk.electionappserver.domain.dto.ElectoralPartyDto,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [candidateDto.electoralParty,electoralParty]; arguments []; default message [electoralParty]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'com.pk.electionappserver.domain.dto.ElectoralPartyDto' for property 'electoralParty'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'com.pk.electionappserver.domain.dto.ElectoralPartyDto' for property 'electoralParty': no matching editors or conversion strategy found]
Field error in object 'candidateDto' on field 'voteResults': rejected value []; codes [typeMismatch.candidateDto.voteResults,typeMismatch.voteResults,typeMismatch.java.util.List,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [candidateDto.voteResults,voteResults]; arguments []; default message [voteResults]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'java.util.List' for property 'voteResults'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'com.pk.electionappserver.domain.dto.VoteResultDto' for property 'voteResults[0]': no matching editors or conversion strategy found]]
和客户端错误:
Caused by: org.springframework.web.client.HttpClientErrorException$BadRequest: 400 : [{"timestamp":"2020-01-17T16:17:45.333+0000","status":400,"error":"Bad Request","errors":[{"codes":["typeMismatch.candidateDto.education","typeMismatch.education","typeMismatch.com.pk.electionappserver... (3565 bytes)]
at org.springframework.web.client.HttpClientErrorException.create(HttpClientErrorException.java:101)
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:170)
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:112)
at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63)
at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:785)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:743)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:717)
at org.springframework.web.client.RestTemplate.postForObject(RestTemplate.java:443)
at com.pk.electionappclient.Controller.ClientController.createCandidate(ClientController.java:36)
at com.pk.electionappclient.Controller.ClientController.addCandidate(ClientController.java:84)
at com.pk.electionappclient.Controller.admin.NewCandidateController.createNewCandidate(NewCandidateController.java:116)
投票结果实体:
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Entity(name = "VoteResults")
public class VoteResult {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@ManyToOne
@JoinColumn(name = "USERS_ID")
private User user;
@ManyToOne
@JoinColumn(name = "ELECTIONS_ID")
private Election election;
@ManyToMany(cascade = CascadeType.PERSIST)
@JoinTable(
name = "JOIN_VOTERESULTS_CANDIDATES",
joinColumns = {@JoinColumn(name = "VOTERESULTS_ID",referencedColumnName = "ID")},
inverseJoinColumns = {@JoinColumn(name = "CANDIDATES_ID", referencedColumnName = "ID")}
)
private List<Candidate> candidates;
private LocalDateTime voteTime;
}
ElectionList 实体:
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Entity(name = "ELECTION_LISTS")
public class ElectionList {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
private String description;
@ManyToOne
@JoinColumn(name = "ELECTION_ID")
private Election election;
@ManyToOne
@JoinColumn(name = "CONSTITUENCY_ID")
private Constituency constituency;
@OneToMany(
targetEntity = Candidate.class,
mappedBy = "electionList",
cascade = CascadeType.PERSIST,
fetch = FetchType.LAZY
)
private List<Candidate> candidates;
}
选举党实体:
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Entity(name = "ELECTORAL_PARTIES")
public class ElectoralParty {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
private String description;
@OneToMany(
targetEntity = Candidate.class,
mappedBy = "electoralParty",
cascade = CascadeType.PERSIST,
fetch = FetchType.LAZY
)
private List<Candidate> candidates;
@OneToOne(cascade = CascadeType.PERSIST, fetch = FetchType.LAZY)
@JoinColumn(name = "ELECTORAL_PROGRAMMES_ID")
private ElectoralProgramme electoralProgramme;
}
解决方案
- 使用@Valid 添加@RequestBody
- 查询参数将不起作用,因为它将值作为字符串传递,这就是您收到转换错误的原因。这会将对象作为对象@137462 传递。看看这个https://stackoverflow.com/a/36021268/4367186
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