如何使用 MongoTemplate 的 class 属性过滤数据？

Question

我是第一次使用 MongoTemplate。使用 Postman，我正在点击 API 并将 JSON 作为 @RequestBody 传递以获取经过过滤的学生列表。

型号Class

Student.java

package bd.ac.seu.erp.criteriademo.model;

import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.NoArgsConstructor;
import org.springframework.data.annotation.Id;

import javax.validation.constraints.NotNull;

@Data
@NoArgsConstructor
@EqualsAndHashCode
public class Student {
    @Id
    String studentId;

    @NotNull
    Name name;

    String nationality;

}

Name.java

package bd.ac.seu.erp.criteriademo.model;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Name {
    private String firstName;
    private String lastName;
}

控制器

StudentController.java

package bd.ac.seu.erp.criteriademo.Controller;

import bd.ac.seu.erp.criteriademo.Service.StudentService;
import bd.ac.seu.erp.criteriademo.model.Student;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.*;

import java.util.HashMap;
import java.util.List;

@CrossOrigin()
@RestController
public class StudentController {
    StudentService studentService;

    public StudentController(StudentService studentService) {
        this.studentService = studentService;
    }

    @PostMapping("student/filter")
    public ResponseEntity<?> getFilteredList(@RequestBody HashMap<String, String> fieldValueMap) {
        System.out.println("Something");

        MultiValueMap<String, String> multiValueMap = new LinkedMultiValueMap<>();
        multiValueMap.add("requestedBy", "Shamin Asfaq");

        List<Student> studentList = studentService.applyFilter(fieldValueMap);
        return new ResponseEntity<>(studentList, multiValueMap, HttpStatus.OK);
    }
}

服务

StudentService.java

package bd.ac.seu.erp.criteriademo.Service;

import bd.ac.seu.erp.criteriademo.model.Student;
import com.mongodb.MongoClient;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.query.Criteria;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.stereotype.Service;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;

@Service
public class StudentService {

    @Value("${spring.data.mongodb.database}")
    String databaseName;

    public List<Student> applyFilter(HashMap<String,String> fieldValueMap) {

        MongoTemplate mongoTemplate = new MongoTemplate(new MongoClient("127.0.0.1"), databaseName);

        Query query = new Query();

        for(Map.Entry<String,String> keyValuePair: fieldValueMap.entrySet()) {
            query.addCriteria(Criteria.where(keyValuePair.getKey()).is(keyValuePair.getValue()));
        }

        return mongoTemplate.find(query, Student.class);
    }
}

当我通过邮递员点击 API 时，通常这是我作为@RequestBody 发送的内容：

{
    "nationality":"Bangladeshi"
}

..它工作得很好。当我尝试使用 "firstName" 或 "lastName" 属性过滤数据时，问题就开始了。

这是我尝试发送的内容：

{
    "name": {
        "firstName": "Shamin"
    }
}

我从 Postman 那里得到的 return 是：

{
    "timestamp": "2018-08-09T12:01:58.620+0000",
    "status": 400,
    "error": "Bad Request",
    "message": "JSON parse error: Cannot deserialize instance of `java.lang.String` out of START_OBJECT token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.lang.String` out of START_OBJECT token\n at [Source: (PushbackInputStream); line: 2, column: 10] (through reference chain: java.util.HashMap[\"name\"])",
    "path": "/student/filter"
}

显然，我了解到后端正在将 "name" 视为 key，其余部分视为 value .

如何在此处使用 "firstName" 或 "lastName" 属性过滤数据？更通用的是，我如何使用 class 属性或另一个 Class 中的 Class 的属性来过滤数据？

Answer 1

您的地图未在其余控制器中正确反序列化。而不是使用 HashMap。

尝试使用 Student class 作为请求正文或使用 com.fasterxml.jackson.databind.node.ObjectNode 之类的内容并读取值。

public ResponseEntity<?> getFilteredList(@RequestBody ObjectNode req)

或将 Json 更改为：

{
    "name.firstname":"aaa"
}

根据您的需要，我认为您应该看看 QueryDsl，它非常好，您可以使用 GET 请求进行查询 student/filter?name.firstname=xxx，您有很好的示例 link

你只需要在StudentRepository中扩展QuerydslPredicateExecutor：

import org.springframework.data.querydsl.QuerydslPredicateExecutor;
import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface StudentRepository extends PagingAndSortingRepository<Student, String>, QuerydslPredicateExecutor<Student> {
}

然后使用谓词进行查询：

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.querydsl.binding.QuerydslPredicate;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.function.Predicate;

@CrossOrigin()
@RestController
public class StudentController {
    StudentRepository studentService;

    public StudentController(StudentRepository studentService) {
        this.studentService = studentService;
    }

    @GetMapping("student/filter")
    public ResponseEntity<Page<Student>> getFilteredList(@QuerydslPredicate(root = Student.class) Predicate predicate, Pageable pageable) {
        System.out.println("Something");

        MultiValueMap<String, String> multiValueMap = new LinkedMultiValueMap<>();
        multiValueMap.add("requestedBy", "Shamin Asfaq");

        Page<Student> studentList = studentService.findAll(predicate, pageable);
        return new ResponseEntity<>(studentList, multiValueMap, HttpStatus.OK);
    }
}

您还需要将此构建插件添加到您的 pom.xml:

        <plugin>
            <groupId>com.mysema.maven</groupId>
            <artifactId>apt-maven-plugin</artifactId>
            <version>${apt.version}</version>
            <dependencies>
                <dependency>
                    <groupId>com.querydsl</groupId>
                    <artifactId>querydsl-apt</artifactId>
                    <version>${querydsl.version}</version>
                </dependency>
            </dependencies>
            <executions>
                <execution>
                    <phase>generate-sources</phase>
                    <goals>
                        <goal>process</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>target/generated-sources/annotations</outputDirectory>
                        <processor>org.springframework.data.mongodb.repository.support.MongoAnnotationProcessor</processor>
                        <logOnlyOnError>true</logOnlyOnError>
                    </configuration>
                </execution>
            </executions>
        </plugin>

如何使用 MongoTemplate 的 class 属性过滤数据？

How to filter data using class attributes with MongoTemplate?

java

spring-boot

mongotemplate