Mongodb文档到Scala case类
Mongodb文档到Scala case类
提问于 2018-05-09 15:24:48
我使用的是MongoDB scala驱动程序。我在从MongoDB获取记录时遇到问题。以下是我的MongoDB初始化
private val client: MongoClient = MongoClient()
private val database: MongoDatabase = client.getDatabase(“rulemgntdb”)
val WorkOrdercollection: MongoCollection[Document] = database.getCollection("workOrder")查找查询：
MongoFactory.WorkOrdercollection.find().collect().subscribe(
(results: Seq[Document]) =>
println(s”Found: #${results}“)
) 打印结果如下：
Found: #List(Document((_id,BsonString{value=‘5af153f49547a205f9798129’}), (workOrderId,BsonString{value=‘9a9e1ce8-c576-4a15-a1ff-4af780b14b7f’}), (thingId,BsonString{value=‘Mumbai_Robot_3’}), (alertId,BsonString{value=‘Alert_1’}), (description,BsonString{value=‘Robot is not in good condition’}), (lastViewedDate,BsonDateTime{value=1525781377952}), (suggestedMaintenanceDate,BsonDateTime{value=1525781377952}), (startDate,BsonDateTime{value=1525781377952})))我想将这个文档映射到我的Case类。
Case类如下所示：
case class WorkOrder (
var id : String = (new ObjectId()).toString(),
var workOrderId: String,
var thingId : String,
var alertId : String,
var description : String,
val lastViewedDate : Date,
val suggestedMaintenanceDate : Date,
val startDate : Date
)如果我执行以下操作从文档中获取JSON字符串：
MongoFactory.WorkOrdercollection.find(query).subscribe(
(user: Document) => println(user.toJson()), // onNext
(error: Throwable) => println(s"Query failed: ${error.getMessage}"), // onError
() => println("Done") // onComplete
)然后，我将获得以下JSON字符串：
{ “_id” : “5af153f49547a205f9798129", “workOrderId” : “9a9e1ce8-c576-4a15-a1ff-4af780b14b7f”, “thingId” : “Mumbai_Robot_3", “alertId” : “Alert_1", “description” : “Robot is not in good condition”, “lastViewedDate” : { “$date” : 1525781377952 }, “suggestedMaintenanceDate” : { “$date” : 1525781377952 }, “startDate” : { “$date” : 1525781377952 } }我可以在“startDate” : { “$date” : 1525781377952 }中将JSON字符串解析为case类but...Look，但无法将MongoDB日期解析为scala日期。
如何将文档映射到Case类？
回答 2
Stack Overflow用户
发布于 2018-05-09 16:25:08
您需要为$date字段提供自定义编解码器。下面展示了它是如何在play-json中实现的，但在其他JSON库中也有类似的概念：
object WorkOrder {
implicit val dateRead: Reads[Date] =
(__ \ "$date").read[Long].map(date => new Date(date))
implicit val dateWrite: Writes[Date] = new Writes[Date] {
def writes(date: Date): JsValue = Json.obj("$date" -> date.getTime)
}
implicit val codec = Json.format[WorkOrder]
}Stack Overflow用户
发布于 2018-05-09 16:53:18
您可以使用JSON库。
在play-json中
case class WorkOrder (
id: String,
workOrderId: String,
thingId: String,
alertId: String,
description: String,
lastViewedDate: Date,
suggestedMaintenanceDate: Date,
startDate: Date
)
object WorkOrder {
implicit lazy val fmt = Json.format[WorkOrder]
}
def documentToWorkOrder(doc: Document): WorkOrder = {
Json.parse(user.toJson().toString).validate[WorkOrder] match {
case JsSuccess(_, workOrderObj) => workOrderObj
case JsError(throwable) => throw throwable
}
}
//then in your code
MongoFactory.WorkOrdercollection.find(query).subscribe(
(user: Document) => documentToWorkOrder(user),
(error: Throwable) => println(s"Query failed: ${error.getMessage}"),
() => println("Done")
)页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/50247718
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