java - 如何使用文档和 mongo 聚合将 mongo shell 代码转换为 java 代码

Question

如何将这段代码转换为java？如何在java中使用聚合框架？谁能帮帮我吗...

我的java代码:

Document update = new Document("$project",new Document("TOTAL_EMPLOYEE_SALARY",new Document("$sum","$employees.EMP_SALARY")));
 AggregationOutput output = coll.aggregate(update); // throwing some error in eclipse

我的 mongo shell 代码:

db.collection.aggregate([
    { "$project": {
        "TOTAL_EMPLOYEE_SALARY": {
           "$sum": "$employees.EMP_SALARY"
        }
    }}
])

Answer 1

所以使用列表:

List<Document> pipeline = Arrays.<Document>asList(
    new Document("$project",
        new Document("TOTAL_EMPLOYEE_SALARY",new Document("$sum","$employees.EMP_SALARY"))
    )
);

AggregationOutput output = coll.aggregate(pipeline);