In this post, I am going to review how to parse json format data in Scala.
Environment OS: Ubuntu 16.04 Java: openjdk version "1.8.0_131" Scala: 2.10 Build Tool: Apache Maven 3.5.0 IDE: IntelliJ
Add dependencies to pom.xml To parse json format string in Scala, play-json moduleinPlayFramework is available. So add the following dependencies to your pom.xml file.
<!-- https://mvnrepository.com/artifact/com.typesafe.play/play-json_2.10 -->
<dependency>
<groupId>com.typesafe.play</groupId>
<artifactId>play-json_2.10</artifactId>
<version>2.6.2</version>
</dependency>
Brief code review Overview of workflow To test parsing json format data in Scala, the below workflow is followed. 1. Parse json format data and retrieve information, such as IP and user/password, to access XtremIO storage. 2. Send a HTTP GET request and recieve a response in Json-like formatted string data. 3. Convert the string response into json and parse the json data in the responce.
Note that, XtremIO storage used in this test is actually a virtual XMS (XtremIO Management Server), which can be used to simulate how XIO API response works.
{
"ip": "192.168.242.128",
"user": "admin",
"password": "Xtrem10",
"clusters": [
{
"cluster": {
"name": "xbrick113",
"logical-space-in-use": "true",
"ud-ssd-space-in-use": "true",
"data-reduction-ratio": "true",
}
***** omitted *****
}
]
}
To pass the json data to the program as input, java.io.FileInputStream is used. https://stackoverflow.com/questions/34334462/how-to-load-json-file-using-play-with-scala
import java.io.FileInputStream
val stream = new FileInputStream(input)
val json_input = try { Json.parse(stream) } finally { stream.close() }
val storage_ip = (json_input \ "ip").get.as[String]
val user = (json_input \ "user").get.as[String]
val password = (json_input \ "password").get.as[String]
This example is the most simple way to retrieve value from json data. If you want to retrive data in deeper levels, let's say you want to get the name of the cluster "xbrick113", then you can write a code like this.
val cluster_name = (json_input \ "cluster" \ 0 \ "cluster" \ "name").get.as[String]
Here, you can define the type of the value you retrieve from json by adding "as[TYPE]".
The simplest way to convert a JsValue to another type is using JsValue.asT:T.ThisrequiresanimplicitconverteroftypeReads[T]toconvertaJsValuetoT(theinverseofWrites[T]). As with Writes, the JSON API provides Reads for basic types.
Next, send HTTP GET request using XMS information. The following is an example of the function to send HTTP GET request.
def checkXMS(storage_ip: String, user: String, password: String ) = {
val api_path = "/api/json/v2"
val api_url = "https://" + storage_ip + api_path
val http_response = Http(api_url).auth(user, password)
.option(HttpOptions.allowUnsafeSSL)
.asString
http_response.body
}
{
***** omitted *****
"links": [
{
"href": "https://192.168.40.128/api/json/v2/",
"rel": "self"
}
]
}
Let's say you want to get the value corresponding to "href" key, then, at first you need to convert the json-like formatted string into "JsValue" Type (because the type of the response is string but not json). Then, you can parse the response as json format data and retrieve the value you expect.
val JsValue_json_string: JsValue = Json.parse(json_string)
val parse_json_return = (JsValue_json_string \ "children" \ 0 \ "href").get
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