使用 Java 從 mongoDB 檢索文檔數組

Question

我有一個包含員工文件的集合。 每個員工都有一個包含該員工當前參與的項目的文檔數組。問題是我不知道如何獲取/查詢項目數組？

這是此類文檔的示例。

{name : "employe name" , age : "..employe age" , phoneNr : 12334 , projects : 
[{ projectName : "project name" , projectLeder : "project leader" }] }

這是用於檢索文檔中除項目數組之外的值的示例代碼。

public void printEmployees() {

    MongoCursor<Document> cursor = coll.find().iterator();

        while(cursor.hasNext()) {

            Document documentEmployee = cursor.next();
            System.out.println((String) documentEmployee.get("name"));
            System.out.println((Integer) documentEmployee.get("age"));
            System.out.println((Integer) documentEmployee.get("phoneNr"));
            //How do i query/extract the project array?

        }  

  }    

Answer 1

你可以嘗試這樣的事情。

while(cursor.hasNext()) {
   Document documentEmployee = cursor.next();
   System.out.println(documentEmployee.getString("name"));
   System.out.println(documentEmployee.getInteger("age"));
   System.out.println(documentEmployee.getInteger("phoneNr"));
   //Extract
   ArrayList projects = documentEmployee.get("project", ArrayList.class);
   //Map
   for (Object obj : projects) {
         Document project = (Document) obj;
         project.getString("projectName");
   }
}