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Converting RSS feeds to JSON using my API on Android-Kotlin

Jun 28, 2018
2 minute read

So, I was working on one podcast app during my internship with the RSS feed. Basically, an RSS feed is a metadata and contains actual data in specific format. The RSS is based on XML format and includes data inside xml tags. I wanted to extract the URLS, descriptions and other stuffs from that RSS. There are many libraries to parse the XML into readable data but I thought of making an API which will convert the RSS response to JSON. Because JSON format is what we love ;-)

You can check the api here : Send-RSS-Get-JSON

You will get the description of that API on the site also the examples with other languages. For android you can refer to the following example: Here, I am showing you the Retrofit2 approach, I am assuming that you have already added the required dependencies to use retrofit in build.gradle file. If you don’t know where to start then I will suggest you to take the FutureStudio’s this tutorial.

Our URL will be: ` https://send-rss-get-json.herokuapp.com/convert/?u=`

And our Result will be:

{
	  "title": "ISS On-Orbit Status Report",
    "description": "",
    "url": "https://blogs.nasa.gov/stationreport",
    "image": "",
    "items": [
        {
            "title": "ISS Daily Summary Report – 6/26/2018",
            "description": "Predetermined Debris Avoidance Maneuver (PDAM) Status: Last night’s possible PDAM for object #99999 was not required. A second update to the object’s trajectory was received overnight and the Probability of Collision (PC) had dropped well into the green threshold. Concern level was low and PDAM planning was no longer needed. MagVector 3D: The crew relocated …",
            "link": "https://blogs.nasa.gov/stationreport/2018/06/26/iss-daily-summary-report-6262018/",
            "url": "https://blogs.nasa.gov/stationreport/2018/06/26/iss-daily-summary-report-6262018/",
            "created": 1530028819000
        },
        ...
        ...
}

Data Model classes

We’ll create one Model class to get the JSON response and model it according to result here I am taking just description from response:

object Model {
    data class Result(val items: Items)
    data class Items(val description: String)
}

Creating Retrofit2 Service

The following interface will define the retrofit service in your app: Note that the result is return as Model.Result, and as a Observable, which is a Rxjava object that could analog as the endpoint fetcher result generator.

interface ApiService {

    @GET("convert/")
    fun getResult(@Query("u") url: String): Observable<Model.Result>

}

Retrofit Builder

In Kotlin companion object is used to make the create function below resembler the static method of Java Factory pattern. you can add this below your ApiService interface

companion object {
  fun create(): ApiService {

    val retrofit = Retrofit.Builder()
          .addCallAdapterFactory(
              RxJava2CallAdapterFactory.create())
          .addConverterFactory(
              GsonConverterFactory.create())
          .baseUrl("https://send-rss-get-json.herokuapp.com/")
          .build()

    return retrofit.create(ApiService::class.java)
  }
}

Get the result

Before performing actual call just add the two global variables and then the function to call the api

val apiserve by lazy {
    ApiService.create()
}
var disposable: Disposable? = null

private fun fetchResult(url: String) {
  disposable = 
     apiserve.getResult("https://blogs.nasa.gov/stationreport/feed/")
      .subscribeOn(Schedulers.io())
      .observeOn(AndroidSchedulers.mainThread())
      .subscribe(
       { result -> showResult(result.items.description) },
       { error -> showError(error.message) }
      )
}

And some housekeeping stuff

override fun onPause() {
    super.onPause()
    disposable?.dispose()
}

That’s it.

I know I didn’t dig up the topics in this post because there’s a lot to talk.This post is to just describe my API.