在 Java 中使用 ArrayList<Model> 将值存储到 MongoDB

Question

在我的 Java Play 框架应用程序中，我想将 ArrayList 值存储在 mongoDB 中。

我在 JSON 中有 3 个值，分别是 loginid、phone、students；在那个学生是ArrayList。我将数据存储在 mongoDB 中，如下所示：

{  "loginid" : "user@mail.com", "phone" : "0123456789", "students" : [{"firstName" : "Jesse", "lastName" : "Varnell", "age" : "15", "gender" : "M" }, { "firstName" : "John", "lastName" : "Doe", "age" : "13", "gender" : "F"}] }

我正在使用 mongo 查询来存储如下值：

BasicDBObject searchQuery = new BasicDBObject();
BasicDBObject theUserObj = new BasicDBObject();

ArrayList<Student> student = new ArrayList<Student>();
if(studentArray != null && studentArray.size()>=0) {
    Student stud = new Student();
    for(int i = 0; i < studentArray.size(); i++){
        stud = studentArray.get(i);
        student.add(stud);
    }   
}
theUserObj.put("loginid", profile.loginid);
theUserObj.put("phone", profile.phone);
searchQuery.append("loginid", username);
theUserObj.put("students", student);

theUserCollection.update(searchQuery, theUserObj); //Got error on this line.

我收到以下错误：

Execution exception (In /app/controllers/StudentInfo.java around line 176)
IllegalArgumentException occured : can't serialize class models.Student

play.exceptions.JavaExecutionException: can't serialize class models.Student
    at play.mvc.ActionInvoker.invoke(ActionInvoker.java:237)
    at Invocation.HTTP Request(Play!)
Caused by: java.lang.IllegalArgumentException: can't serialize class models.Student
    at org.bson.BasicBSONEncoder._putObjectField(BasicBSONEncoder.java:234)
    at org.bson.BasicBSONEncoder.putIterable(BasicBSONEncoder.java:259)
    at org.bson.BasicBSONEncoder._putObjectField(BasicBSONEncoder.java:198)
    at org.bson.BasicBSONEncoder.putObject(BasicBSONEncoder.java:140)
    at org.bson.BasicBSONEncoder.putObject(BasicBSONEncoder.java:86)
    at com.mongodb.DefaultDBEncoder.writeObject(DefaultDBEncoder.java:27)
    at com.mongodb.OutMessage.putObject(OutMessage.java:142)
    at com.mongodb.DBApiLayer$MyCollection.update(DBApiLayer.java:346)
    at com.mongodb.DBCollection.update(DBCollection.java:165)
    at com.mongodb.DBCollection.update(DBCollection.java:197)
    at com.mongodb.DBCollection.update(DBCollection.java:209)
    at controllers.StudentInfo.doStoreProfile(StudentInfo.java:176)
    at controllers.StudentInfo.storeUserProfile(StudentInfo.java:212)
    at play.mvc.ActionInvoker.invokeWithContinuation(ActionInvoker.java:557)
    at play.mvc.ActionInvoker.invoke(ActionInvoker.java:508)
    at play.mvc.ActionInvoker.invokeControllerMethod(ActionInvoker.java:484)
    at play.mvc.ActionInvoker.invokeControllerMethod(ActionInvoker.java:479)
    at play.mvc.ActionInvoker.invoke(ActionInvoker.java:161)

如何使用 Java 在 MongoDB 中使用 ArrayList 存储值？

Answer 1

DBObject并且实现类只能处理 BSON 类型，而你的Student类不是。

有很多框架可以映射| 将域对象（例如 Student）转换为 | 来自 BSON 表示和文档。由于您显然不使用任何，因此您必须手动将每个转换Student为您DBObject自己。

BasicDBObject searchQuery = new BasicDBObject("loginid", username);
BasicDBObject theUserObj = new BasicDBObject();

List<Object> studentsDBList = new BasicDBList();

for (Student student : studentArray) {
    DBObject studentDBObject = new BasicDBObject();
    studentDBObject.put("firstName", student.getFirstName());
    studentDBObject.put("lastName", student.getLastName());
    studentDBObject.put("age", student.getAge());
    studentDBObject.put("gender", student.getGender());
    studentsDBList.add(studentDBObject);
} 

theUserObj.put("phone", profile.phone);
theUserObj.put("students", studentsDBList);

theUserCollection.update(searchQuery, theUserObj); 

另外，请注意，您不必loginid放入theUserObj，因为您只是在查询它