· Oct 5, 2018

JSON array or JSON object?

Hello everyone,

i already asked this question in another post ( and i'm sorry for creating a new post but i still didn't get an answer so i try it again. Now i know how to import my JSON formatted data from my API to my DocDB but now i have the problem that my JSON formatted data from my API is imported only to the %Doc  column and not to the columns that i created with my properties.  I'm not really sure but i think that the document database only puts my information from my API to the right columns if my JSON is in a JSONArrray format. But the format of my API is JSONObject and looks like this:

  "artists": {
    "artist": [
        "name": "Tough Love",
        "playcount": "279426",
        "listeners": "58179",
        "mbid": "d07276bc-3874-4deb-8699-35c9948be0cc",
        "url": "",
        "streamable": "0",
        "image": [
            "#text": "",
            "size": "small"
            "#text": "",
            "size": "medium"
            "#text": "",
            "size": "large"
            "#text": "",
            "size": "extralarge"
            "#text": "",
            "size": "mega"

Is there a possibility to convert the  format from JSONObject to JSONArray or do i have to parse it? I want to import only the body from my API with "name", "playcount", "listeners" and so on as my headers without "artists" and  without "artist".  I just want to leave off the first two headers. 

Thank you in advance. 

Discussion (6)0
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Im trying to store the properties "name", "playcount", "listeners", "mbid", "url" not the "artist" or the "artists" property. I think that my document class definition is at the bottom of my code :

Class User.API


ClassMethod getFile() as %Status



       IF $SYSTEM.DocDB.Exists("db.Streamingdatabase") {

             SET db = ##class(%DocDB.Database).%GetDatabase("db.Streamingdatabase")


             ELSE {

                    SET db = ##class(%DocDB.Database).%CreateDatabase("db.Streamingdatabase")


             DO db.%CreateProperty("Name","%String(MAXLEN=200)","$.name")

             DO db.%CreateProperty("Duration","%Integer","$.duration")

             DO db.%CreateProperty("Playcount","%Integer","$.playcount")

             DO db.%CreateProperty("Mbid","%String(MAXLEN=200)","$.mbid")

             DO db.%CreateProperty("Url","%String(MAXLEN=200)","$.url")

             DO db.%CreateProperty("StreamableText","%Integer","$.streamable/#text")

             DO db.%CreateProperty("StreamableFulltrack","%Integer","$.streamable/fulltrack")

             DO db.%CreateProperty("ArtistName","%String(MAXLEN=200)","$.artist/name")

             DO db.%CreateProperty("ArtistMbid","%String(MAXLEN=200)","$.artist/mbid")

             DO db.%CreateProperty("ArtistURL","%String(MAXLEN=200)","$.artist/url")

             DO db.%CreateProperty("Rank","%Integer","$.@attr/rank")


             SET httprequest=##class(%Net.HttpRequest).%New()

             DO httprequest.Get("")

             DO db.%FromJSON(httprequest.HttpResponse.Data)




This is just an idea, and I may be corrected on this.
You get an array of artists. I can't find anything on storing arrays of the same key as you have in this scenario.

I would first do the web-service call.

  • Then create a DynamicObject using %FromJSON and the http response data as the source.
  • Get the array of artist from the DynamicObject using %Get("artists") on the DynamicObject instance.
  • Create an iterator on the object returned by the previous command using %GetIterator
  • Iterate through the collection - for each
    • Create a docdb entry and the properties or open an existing one. I recommend creating a separate method for this to keep the code concise.
    • Create a JSON stream of the current object on the iterator using %ToJSON(.tMyStream)
    • DO db.%FromJSON(.tMyStream)