如何解析从 HTTP 接收到的 Json 字符串并循环遍历这些值
How to Parse Json String received from HTTP and loop through the values
我正在使用 Scala 和 Swagger,我需要帮助弄清楚如何遍历 json 中的值并将这些值用于检查和其他。
HTTP get 请求后返回的 json 字符串如下所示:
{
"count": 3,
"items": [
{
"Id": "fd0a9e5a",
"DbName": "Xterior Prod",
"Name": "XP"
},
{
"Id": "4158a1a6",
"DbName": "Invidibi Pappear",
"Name": "ISP"
},
{
"Id": "7e0c57046d3f",
"DbName": "Multi Test",
"Name": "MMP"
}]
}
我的 UI 允许用户输入 ID。我要做的是遍历从 API 返回的 Json 值并找到与输入的 ID 相匹配的值。找到匹配项后,我必须检查数据库中是否包含 "Test" 关键字。如果是这样,我将需要显示 DbName 和短名称。
我在这里找到了一些指南(例如 Foreach with JSON Arrays in Play2 and Scala),但它对我不起作用。当我 运行 我的代码时,我得到这个错误:
play.api.libs.json.JsResultException: JsResultException(errors:List(((0)/Id,List(ValidationError(List(error.path.missing),WrappedArray()))), ((0)/DbName,List(ValidationError(List(error.path.missing),WrappedArray()))), ((1)/Id,List(ValidationError(List(error.path.missing),WrappedArray()))), ((1)/DbName,List(ValidationError(List(error.path.missing),WrappedArray()))), ((2)/Id,List(ValidationError(List(error.path.missing),WrappedArray()))), ((2)/DbName,List(ValidationError(List(error.path.missing),WrappedArray()))),
这是我的代码:
case class DBInfo(Id: String, DbName: String, Name: String)
contentType = "application/json"
//get json from http
val httpClient = HttpClients.createDefault()
val httpResponse = httpClient.execute(new HttpGet("http://www.customers.com/dbInfo"))
val entity = httpResponse.getEntity
val content = fromInputStream(httpResponse.getEntity.getContent()).getLines().mkString
implicit val dbReader = Json.reads[DBInfo]
val dbList = (Json.parse(content) \ "items").as[List[DBInfo]]
dbList.foreach { dbI =>
if (dbI.Id == id)
if (dbI.DbName.contains("Test"))
println(dbI.DbName + " - " + dbI.Name)
else BadRequest("Not allowed")
else
BadRequest("ID not found")
}
id 是保存用户输入的ID 的变量。有人可以告诉我错误的原因以及如何解决吗?谢谢。
注意:请使用 import org.json4s.JsonAST 或 import play.api.libs.json
这是一种使用 circe 的方法。您可以使用 Cursor 导航 JSON,并使用 Decoder[A]
类型类解码到 Environment
的列表。请注意,您使用的是 Either[Failure, A]
值。
import io.circe._
case class Environment(id: String, dbName: String, name: String)
implicit val environmentDecoder: Decoder[Environment] = Decoder.instance[Environment] {
json =>
for {
id <- json.downField("Id").as[String]
dbName <- json.downField("DbName").as[String]
name <- json.downField("Name").as[String]
} yield {
Environment(id, dbName, name)
}
}
// alternatively:
// implicit val environmentDecoder: Decoder[Environment] =
// Decoder.forProduct3[String, String, String, Environment]("Id", "DbName", "Name")(Environment.apply)
val text =
"""{
| "count": 3,
| "items": [{
| "Id": "fd0a9e5a",
| "DbName": "Xterior Prod",
| "Name": "XP"
| }, {
| "Id": "4158a1a6",
| "DbName": "Invidibi Pappear",
| "Name": "ISP"
| }, {
| "Id": "7e0c57046d3f",
| "DbName": "Multi Match Test",
| "Name": "MMP"
| }]
|}
""".stripMargin
val json = parser.parse(text).fold(_ => ???, json => json)
val res: Either[DecodingFailure, List[Environment]] = json.hcursor.downField("items").as[List[Environment]]
println(res)
// Right(List(Environment(fd0a9e5a,Xterior Prod,XP), Environment(4158a1a6,Invidibi Pappear,ISP), Environment(7e0c57046d3f,Multi Match Test,MMP)))
// or simply
// val res2 = parser.parse(text).right
// .flatMap(_.hcursor.downField("items").as[List[Environment]])
您还可以使用 http4s' http4s-blaze-client and http4s-circe 进行 HTTP 请求:
import org.http4s._
import org.http4s.circe._
import scalaz.concurrent._
val client = org.http4s.client.blaze.defaultClient
val fetchEnvironments: Task[List[Environment]] =
client.fetchAs[Json](Request(Method.GET, Uri.uri("http://example.com")))
.flatMap { json =>
json.hcursor.downField("items").as[List[Environment]].fold(
failure => Task.fail(failure),
xs => Task.now(xs)
)
}
val xs = fetchEnvironments.unsafePerformSync
已经有了答案。所以我就是这样做的:
case class databaseInfo(Id: String, DbName: String, Name: String)
class dbInfo{
def CheckDb(id: String): Option[String] = {
val httpClient = HttpClients.createDefault()
val httpResponse = httpClient.execute(new HttpGet("http://example.com"))
val content = fromInputStream(httpResponse.getEntity.getContent()).getLines().mkString
val envItems = (parse(content) \ "items").children
for (items <- envItems) {
val dbItems = items.extract[databaseInfo]
if (dbItems.EnvId == Some(id)) {
if (equalsIgnoreCase(dbItems.DbName.mkString, "Test")) //do something
else //do something
}
}
None
}
}
我正在使用 Scala 和 Swagger,我需要帮助弄清楚如何遍历 json 中的值并将这些值用于检查和其他。
HTTP get 请求后返回的 json 字符串如下所示:
{
"count": 3,
"items": [
{
"Id": "fd0a9e5a",
"DbName": "Xterior Prod",
"Name": "XP"
},
{
"Id": "4158a1a6",
"DbName": "Invidibi Pappear",
"Name": "ISP"
},
{
"Id": "7e0c57046d3f",
"DbName": "Multi Test",
"Name": "MMP"
}]
}
我的 UI 允许用户输入 ID。我要做的是遍历从 API 返回的 Json 值并找到与输入的 ID 相匹配的值。找到匹配项后,我必须检查数据库中是否包含 "Test" 关键字。如果是这样,我将需要显示 DbName 和短名称。
我在这里找到了一些指南(例如 Foreach with JSON Arrays in Play2 and Scala),但它对我不起作用。当我 运行 我的代码时,我得到这个错误:
play.api.libs.json.JsResultException: JsResultException(errors:List(((0)/Id,List(ValidationError(List(error.path.missing),WrappedArray()))), ((0)/DbName,List(ValidationError(List(error.path.missing),WrappedArray()))), ((1)/Id,List(ValidationError(List(error.path.missing),WrappedArray()))), ((1)/DbName,List(ValidationError(List(error.path.missing),WrappedArray()))), ((2)/Id,List(ValidationError(List(error.path.missing),WrappedArray()))), ((2)/DbName,List(ValidationError(List(error.path.missing),WrappedArray()))),
这是我的代码:
case class DBInfo(Id: String, DbName: String, Name: String)
contentType = "application/json"
//get json from http
val httpClient = HttpClients.createDefault()
val httpResponse = httpClient.execute(new HttpGet("http://www.customers.com/dbInfo"))
val entity = httpResponse.getEntity
val content = fromInputStream(httpResponse.getEntity.getContent()).getLines().mkString
implicit val dbReader = Json.reads[DBInfo]
val dbList = (Json.parse(content) \ "items").as[List[DBInfo]]
dbList.foreach { dbI =>
if (dbI.Id == id)
if (dbI.DbName.contains("Test"))
println(dbI.DbName + " - " + dbI.Name)
else BadRequest("Not allowed")
else
BadRequest("ID not found")
}
id 是保存用户输入的ID 的变量。有人可以告诉我错误的原因以及如何解决吗?谢谢。
注意:请使用 import org.json4s.JsonAST 或 import play.api.libs.json
这是一种使用 circe 的方法。您可以使用 Cursor 导航 JSON,并使用 Decoder[A]
类型类解码到 Environment
的列表。请注意,您使用的是 Either[Failure, A]
值。
import io.circe._
case class Environment(id: String, dbName: String, name: String)
implicit val environmentDecoder: Decoder[Environment] = Decoder.instance[Environment] {
json =>
for {
id <- json.downField("Id").as[String]
dbName <- json.downField("DbName").as[String]
name <- json.downField("Name").as[String]
} yield {
Environment(id, dbName, name)
}
}
// alternatively:
// implicit val environmentDecoder: Decoder[Environment] =
// Decoder.forProduct3[String, String, String, Environment]("Id", "DbName", "Name")(Environment.apply)
val text =
"""{
| "count": 3,
| "items": [{
| "Id": "fd0a9e5a",
| "DbName": "Xterior Prod",
| "Name": "XP"
| }, {
| "Id": "4158a1a6",
| "DbName": "Invidibi Pappear",
| "Name": "ISP"
| }, {
| "Id": "7e0c57046d3f",
| "DbName": "Multi Match Test",
| "Name": "MMP"
| }]
|}
""".stripMargin
val json = parser.parse(text).fold(_ => ???, json => json)
val res: Either[DecodingFailure, List[Environment]] = json.hcursor.downField("items").as[List[Environment]]
println(res)
// Right(List(Environment(fd0a9e5a,Xterior Prod,XP), Environment(4158a1a6,Invidibi Pappear,ISP), Environment(7e0c57046d3f,Multi Match Test,MMP)))
// or simply
// val res2 = parser.parse(text).right
// .flatMap(_.hcursor.downField("items").as[List[Environment]])
您还可以使用 http4s' http4s-blaze-client and http4s-circe 进行 HTTP 请求:
import org.http4s._
import org.http4s.circe._
import scalaz.concurrent._
val client = org.http4s.client.blaze.defaultClient
val fetchEnvironments: Task[List[Environment]] =
client.fetchAs[Json](Request(Method.GET, Uri.uri("http://example.com")))
.flatMap { json =>
json.hcursor.downField("items").as[List[Environment]].fold(
failure => Task.fail(failure),
xs => Task.now(xs)
)
}
val xs = fetchEnvironments.unsafePerformSync
已经有了答案。所以我就是这样做的:
case class databaseInfo(Id: String, DbName: String, Name: String)
class dbInfo{
def CheckDb(id: String): Option[String] = {
val httpClient = HttpClients.createDefault()
val httpResponse = httpClient.execute(new HttpGet("http://example.com"))
val content = fromInputStream(httpResponse.getEntity.getContent()).getLines().mkString
val envItems = (parse(content) \ "items").children
for (items <- envItems) {
val dbItems = items.extract[databaseInfo]
if (dbItems.EnvId == Some(id)) {
if (equalsIgnoreCase(dbItems.DbName.mkString, "Test")) //do something
else //do something
}
}
None
}
}