How can i import my JSON formatted data from my API to my docDB?

Hi,

Sorry not getting back to you sooner - I was on a flight.

You are on the right track. You just need to understand the makeup  of the data returned.

So - to recap - in IRIS you are preparing a Document database - a collection of JSON documents. Each document represents an 'artist', with 'name', 'playcount', 'listeners' and other  properties.

The JSON string for 1 such entry (artist), or document in the collections would be look something like this, which is embedded actually, in the whole JSON your HTTP request returns..:

{
        "name": "Tough Love",
        "playcount": "279426",
        "listeners": "58179",
        "mbid": "d07276bc-3874-4deb-8699-35c9948be0cc",
        "url": "https://www.last.fm/music/Tough+Love",
        "streamable": "0",
        "image": [
          {
            "#text": "https://lastfm-img2.akamaized.net/i/u/34s/3fa24f60a855fdade245138dead7ec...",
            "size": "small"
          },...

}

If you extracted each artist document in the collection,  you can insert it into the database individually like this:

do db.%SaveDocument({"name":"Tough love","playcount":"279426",... })

The %SaveDocument method takes a single JSON dynamic object and inserts into the collection.  The whole JSON blob goes into the %DocDB 'column' of the projected table, and, for some elements like 'name' specifically created as columns via %CreateProperty - will be individually populated as column values.

But  - as mentioned earlier - the output from your HTTP call returns JSON which, down a few levels deep, has a collection of 'artist' documents :

{
  "artists": {
    "artist": [           <-- This is where the collection of artists starts from
      {
        "name": "Tough Love",
        "playcount": "279426",

Here are two approaches:

1. Option #1 - iterate through the correct part of your returned data, to extract individually each artist. (I prefer the next option #2)

Using the returned whole JSON, access the element 'artists', - and then, it's property 'artist'.  This element (represented by path "artists.artist", (poorly named imho), is actually the collection.  Use an iterator to iterate through each item in the collection.  

set wholeJSON={}.%FromJSON(httprequest.HttpResponse.Data)
set iArtist=wholeJSON.artists.artist.%GetIterator()  // iArtist is the iterator for the collection of artist JSON's
while iArtist.%GetNext(.key,.value) {
    // key is the item number in the collection
    // value is a dynamic object of the item in this collection
    do db.%SaveDocument(value)  //  insert 1 artist at a time.
}

2.  As you have discovered, you can use db.%FromJSON to import a whole collection of documents, in one hit, but, what you supply, should be a string or stream in JSON format, representing an array of documents, which the raw HttpResponse.Data is not because of the leading elements 'artists', etc..- but you can dive in and get the array:

set wholeJSON={}.%FromJSON(httprequest.HttpResponse.Data)
set arrArtists=wholeJSON.artists.artist   // this is the collection of artists
do db.%FromJSON(arrArtists.%ToJSON())  // need to give %FromJSON a json string.

.. and in one GULP, ALL artist documents, ie , all items in the collection, are added into the document database (I tried this - I confirm 1000 rows created).

Use option 1 if you want to filter the injection of data into your document database, or option 2 if you want to do a batch upload in one hit.

Let us know how you get on...

Steve