Display JSON array elements as one line in U-SQL - arrays

Question

How do I display each JSON array element as a comma separated element in one line, rather than one element per line, in U-SQL?
For example, the JSON file is:
{
"A": {
"A1": "1",
"A2": 0
},
"B": {
"B1": "1",
"B2": 0
},
"C": {
"C1": [
{
"D1": "1"
},
{
"D2": "2"
},
{
"D3": "3"
},
{
"D4": "4"
},
{
"D5": "5"
},
{
"D6": "6"
},
{
"D7": "7"
}
]
}
}
The code to process this fragment for the array C1 is as follows:
#sql = SELECT
Microsoft.Analytics.Samples.Formats.Json.JsonFunctions.JsonTuple(C)["C1"] AS C1_array
FROM #json;
OUTPUT #sql TO "test.txt" USING Outputters.Csv(quoting: false);
#sql2 = SELECT
Microsoft.Analytics.Samples.Formats.Json.JsonFunctions.JsonTuple(C1_array) AS C1
FROM #sql
CROSS APPLY
EXPLODE (Microsoft.Analytics.Samples.Formats.Json.JsonFunctions.JsonTuple(C1_array).Values) AS D(C1);
#result =
SELECT C1["D1"]AS D1,
C1["D2"] AS D2,
C1["D3"]AS D3,
C1["D4"]AS D4,
C1["D5"]AS D5,
C1["D6"]AS D6,
C1["D7"]AS D7,
FROM #sql2;
OUTPUT #result TO "output.txt" USING Outputters.Text();
The result that all the array elements print out as one per line, ie, all the D1 through D7 elements are on separate lines. I want the D1 through D7 elements to be part of the same line, as it is part of the JSON object.
That is:
1, 2, 3, 4, 5, 6, 7
How can this be done?

Answer 1

The important part is that the C1 array contains one item per Di. So if you treat it as an item per row, you will get separate rows. In this case you want one row for all of C1.
The following does this in two ways: One time you know what the Ds are and one time if you do not know and still want them in one row (now all in one cell).
REFERENCE ASSEMBLY JSONBlog.[Newtonsoft.Json];
REFERENCE ASSEMBLY JSONBlog.[Microsoft.Analytics.Samples.Formats];
// Get one row per C and get the C1 array as column
#d = EXTRACT C1 string FROM "/Temp/ABCD.txt" USING new Microsoft.Analytics.Samples.Formats.Json.JsonExtractor("C");
// Keep one row per C and get all the items from within the C1 array
#d =
SELECT Microsoft.Analytics.Samples.Formats.Json.JsonFunctions.JsonTuple(C1, "[*].*") AS DMap
FROM #d;
// Get individual items
#d1 =
SELECT
DMap["[0].D1"] AS D1,
DMap["[1].D2"] AS D2,
DMap["[2].D3"] AS D3,
DMap["[3].D4"] AS D4,
DMap["[4].D5"] AS D5,
DMap["[5].D6"] AS D6,
DMap["[6].D7"] AS D7
FROM #d;
// Keep it generic and get all item in a single column
#d2 =
SELECT String.Join("\t", DMap.Values) AS Ds
FROM #d;
OUTPUT #d1
TO "/Temp/D-Out1.tsv"
USING Outputters.Tsv();
OUTPUT #d2
TO "/Temp/D-Out2.tsv"
USING Outputters.Tsv(quoting:false);
As you can see, the JsonTuple function can take a JSONPath expression and then it uses all found paths in the resulting map as keys.