找不到能够从类型 [java.util.LinkedHashMap 进行转换的转换器<?, ?> ] 输入

Question

I have documents like this in a couchbase DB

{

  "hostel": {
    "city": {}
    ...
  }
}

and I have this query defined in a repository

@Query("UPDATE #{#n1ql.bucket} SET hostel.state = $2 where hostel.id=$1 RETURNING #{#n1ql.bucket}.hostel    ")
Hostel update(String entityId, String newState);

but when I run it I got this error:

org.springframework.core.convert.ConverterNotFoundException: 
No converter found capable of converting from type [java.util.LinkedHashMap<?, ?>] to type [com.model.Hostel]

and the Hostel type:

@Data
@Builder
@AllArgsConstructor
@JsonInclude(NON_NULL)
@EqualsAndHashCode
public class Hostel {

    private @NotNull String id;
    private @NotNull String city;
    private JsonObject commodities;
}

I also tried with:

@Query("UPDATE #{#n1ql.bucket} SET hostel.state = $2 where hostel.id=$1 RETURNING #{#n1ql.bucket}.hostel    ")
void update(String entityId, String newState);

but then I got the error:

org.springframework.data.couchbase.core.CouchbaseQueryExecutionException: Query returning a primitive type are expected to return exactly 1 result, got 0

Answer 1

According to Spring Data: Modifying Query

You can specify the following return types:

• void

• int (updated record count)

• boolean(whether a record was updated)

In your case you have return type Hostel what is not good if you are using SpringData . Spring can not convert result of query execution to Hostel type. Try to use one of type specified earlier