[SOLVED] While Loop Read and JQ, use array list of column names

While Loop Read and JQ, use array list of column names

I want to pass a "array" to the while loop so I don't have to repeat the column names

COLUMNS=("SOURCE_FILE" "EXIF_CONTAINER" "EXIF_CODEC" "EXIF_ENCODER")

while IFS=',' read -r SOURCE_FILE EXIF_CONTAINER EXIF_CODEC EXIF_ENCODER
do
   #Do Processing here 
done < <(
   echo "$EXIF_DATA"  | jq -cr '.[] | "\(.SourceFile),\(.EXIF_CONTAINER),\(.EXIF_CODEC), \(.EXIF_ENCODER)"'
)

How do I make the "while loop read" and "jq" use the COLUMNS list instead of having to repeat the column names?

Solution

For while read, just expand the array instead of listing all variable names.

Change

while IFS=',' read -r SOURCE_FILE EXIF_CONTAINER EXIF_CODEC EXIF_ENCODER

into

while IFS=',' read -r "${COLUMNS[@]}"

As for jq, use the --args flag to supply multiple arguments at once, populating jq's $ARGS.positional array. Then, here as well, just expand your Bash array as additional arguments.

Change

jq -r '.[] | "\(.SOURCE_FILE),\(.EXIF_CONTAINER),\(.EXIF_CODEC),\(.EXIF_ENCODER)"'

into

jq -r '.[] | [.[$ARGS.positional[]]] | join(",")' --args "${COLUMNS[@]}"

Note: Watch out for upper/lower case column/field names (e.g. SourceFile vs. SOURCE_FILE), and better use lowercase variable names in Bash (e.g. columns instead of COLUMNS)