JQ Group By by Key, Merge Value, then Flatten Object - jq

Question

With the following inputs:
# file1.json
{
"uid": "1",
"name": "jack"
}
{
"uid": "2",
"name": "jill"
}
# file2.json
{
"fid": "a",
"file": "sample1.txt",
"uid": "1"
}
{
"fid": "b",
"file": "sample2.txt",
"uid": "1"
}
{
"fid": "c",
"file": "sample3.txt",
"uid": "2"
}
How do I go about inserting the name key-value pair to the object in the file2.json. The output I'm trying to get is as follows:
{
"fid": "a",
"file": "sample1.txt",
"uid": "1",
"name": "jack"
}
{
"fid": "b",
"file": "sample2.txt",
"uid": "1",
"name": "jack"
}
{
"fid": "c",
"file": "sample3.txt",
"uid": "2",
"name": "jill"
}
Solutions posted on merge json objects with jq and join two json files based on common key with jq utility or alternative way from command line both seems to only return the last matching pair. See below.
{"uid":"1","name":"jack","fid":"b","file":"sample2.txt"}
{"uid":"2","name":"jill","fid":"c","file":"sample3.txt"}

Answer 1

You will need to "slurp" file1.json, e.g. by invoking jq as follows:
jq -n -f merge.jq --slurpfile file1 file1.json file2.json
where merge.jq contains:
INDEX($file1[]; .uid) as $dict
| inputs
| . + $dict[.uid]
def INDEX
If your jq does not have INDEX/2, then simply add its def:
def INDEX(stream; idx_expr):
reduce stream as $row ({}; .[$row|idx_expr|tostring] = $row);