Power Query: Structured record while converting to JSON - powerbi

Question

I have a power query record as follows:
Data = [
tracker = {
[
foo = {
[
field_a= "Something",
field_b = "data2"
],
[
field_a= "Something",
field_c = "data2"
]
},
bar = "Data"
],
[
foo = {
[
field_c= "Something",
field_b = "data2"
],
[
field_a= "Something",
field_c = "data2"
]
},
bar = "Data2"
]
}
]
When I convert it into a JSON, I obtain this:
{
"tracker": [
{
"foo": [
{
"field_a": "Something",
"field_b": "data2"
},
{
"field_a": "Something",
"field_c": "data2"
}
],
"bar": "Data"
},
{
"foo": [
{
"field_c": "Something",
"field_b": "data2"
},
{
"field_a": "Something",
"field_c": "data2"
}
],
"bar": "Data2"
}
]
}
I need the foo array to have structured objects within it, in the sense that each object should have field_a, field_b, field_c in it. Example:
foo = {
[
field_c= "Something",
field_b = "data2",
field_a = null
],
[
field_a= "Something",
field_c = "data2".
field_b = null
]
}
I tried using
List.Transform(x, each Record.TransformFields(_, {
{ "field_a", Text.Trim },
{ "field_b", Text.Trim },
{ "field_c", Text.Trim }
}, MissingField.UseNull))
however, I am losing reference to the bar field in the final output. Any help would be appreciated.

Answer 1

This seems to work for me.
let
Data = [
tracker = {
[
foo = {
[
field_a= "Something",
field_b = "data2"
],
[
field_a= "Something",
field_c = "data2"
]
},
bar = "Data"
],
[
foo = {
[
field_c= "Something",
field_b = "data2"
],
[
field_a= "Something",
field_c = "data2"
]
},
bar = "Data2"
]
}
],
#"Converted to Table" = Record.ToTable(Data),
#"Added Custom" = Table.AddColumn(#"Converted to Table", "Custom",
each let
a = [Value],
b = List.Transform(a, each Record.TransformFields(_, {
{ "foo", (x)=> List.Transform(x, (y)=> Record.TransformFields(y, {
{ "field_a", Text.Trim },
{ "field_b", Text.Trim },
{ "field_c", Text.Trim }
}, MissingField.UseNull) )}
}))
in b)
in
#"Added Custom"

Answer 2

Try this in powerquery
It splits on } then checks for the fields defined in the first row, and if one or two of them are missing, adds them, then puts the pieces back together
let TableWithPhrases = Table.Buffer(#table({"Keyword"}, {{"field_a"}, {"field_b"}, {"field_c"}})),
Source = [tracker = {[foo = {[
field_a= "Something",
field_b = "data2"
],
[
field_a= "Something",
field_c = "data2"
]
},
bar = "Data"
],
[
foo2 = {
[
field_c= "Something",
field_b = "data2"
],
[
field_a= "Something",
field_c = "data2"
]
},
bar = "Data2"
]
}
],
prior =Text.FromBinary(Json.FromValue(Source[tracker])),
Splitit=Text.Split(prior,"}"),
#"Converted to Table" = Table.FromList(Splitit, Splitter.SplitByNothing(), null, null, ExtraValues.Error),
#"Changed Type" = Table.TransformColumnTypes(#"Converted to Table",{{"Column1", type text}}),
#"Added Custom" = Table.AddColumn(#"Changed Type", "Custom", each List.Select(TableWithPhrases[Keyword], (x) => not(Text.Contains([Column1], x)))),
#"Added Custom1" = Table.AddColumn(#"Added Custom", "Custom.1", each if List.Count([Custom])=Table.RowCount(TableWithPhrases) then "" else Text.Combine(List.Transform([Custom], each ","""&_&""":"""""))),
#"Added Custom2" = Table.AddColumn(#"Added Custom1", "Custom.2", each [Column1]&[Custom.1]),
final = Text.Combine(#"Added Custom2"[Custom.2],"}")
in final
Before
[{"foo":[{"field_a":"Something","field_b":"data2"},{"field_a":"Something","field_c":"data2"}],"bar":"Data"},{"foo2":[{"field_c":"Something","field_b":"data2"},{"field_a":"Something","field_c":"data2"}],"bar":"Data2"}]
After
[{"foo":[{"field_a":"Something","field_b":"data2","field_c":""},{"field_a":"Something","field_c":"data2","field_b":""}],"bar":"Data"},{"foo2":[{"field_c":"Something","field_b":"data2","field_a":""},{"field_a":"Something","field_c":"data2","field_b":""}],"bar":"Data2"}]