Only one json line was read in rjson - r

Question

The code is
library(rjson)
url <- 'file.json'
j <- fromJSON(file=url, method='C')
there are more than 1000 lines in the file.json, however, the returned result is a list of 9.
the file.json is
{"reviewerID": "A30TL5EWN6DFXT", "asin": "120401325X", "reviewerName": "christina", "helpful": [0, 0], "reviewText": "They look good and stick good! I just don't like the rounded shape because I was always bumping it and Siri kept popping up and it was irritating. I just won't buy a product like this again", "overall": 4.0, "summary": "Looks Good", "unixReviewTime": 1400630400, "reviewTime": "05 21, 2014"}
{"reviewerID": "ASY55RVNIL0UD", "asin": "120401325X", "reviewerName": "emily l.", "helpful": [0, 0], "reviewText": "These stickers work like the review says they do. They stick on great and they stay on the phone. They are super stylish and I can share them with my sister. :)", "overall": 5.0, "summary": "Really great product.", "unixReviewTime": 1389657600, "reviewTime": "01 14, 2014"}
{"reviewerID": "A2TMXE2AFO7ONB", "asin": "120401325X", "reviewerName": "Erica", "helpful": [0, 0], "reviewText": "These are awesome and make my phone look so stylish! I have only used one so far and have had it on for almost a year! CAN YOU BELIEVE THAT! ONE YEAR!! Great quality!", "overall": 5.0, "summary": "LOVE LOVE LOVE", "unixReviewTime": 1403740800, "reviewTime": "06 26, 2014"}
what is the problem? thanks!

Answer 1

Your file does not contain valid JSON. You basically have three JSON hashes sitting right next to each other. The exact choice of whitespace that separates the values doesn't matter. It's equivalent to this:
{} {} {}
That's just as invalid as if it was three primitives sitting right next to each other:
3 'a' true
Speaking generally, when the input to a function is invalid, all bets are off. It is desirable to write functions to fail gracefully and emit clear error messages that describe the nature of the invalidity, and very often that is the case, but that doesn't always happen. In this case, what rjson::fromJSON() seems to be doing when it encounters this kind of invalid JSON is to parse and return the first value, and silently ignore everything else. That's unfortunate, but what can we do.
You should probably investigate how the file was generated, and seek to correct the problem at that end. But if you want to hack a solution, we can read in the lines of JSON into a character vector, paste-collapse them on comma, paste bracket delimiters around the resulting string, and then parse that string to get an array of hashes. This will only work if each adjacent hash occupies exactly one line in the file.
fromJSON(paste0('[',paste(collapse=',',readLines(url)),']'));
## [[1]]
## [[1]]$reviewerID
## [1] "A30TL5EWN6DFXT"
##
## [[1]]$asin
## [1] "120401325X"
##
## [[1]]$reviewerName
## [1] "christina"
##
## [[1]]$helpful
## [1] 0 0
##
## [[1]]$reviewText
## [1] "They look good and stick good! I just don't like the rounded shape because I was always bumping it and Siri kept popping up and it was irritating. I just won't buy a product like this again"
##
## [[1]]$overall
## [1] 4
##
## [[1]]$summary
## [1] "Looks Good"
##
## [[1]]$unixReviewTime
## [1] 1400630400
##
## [[1]]$reviewTime
## [1] "05 21, 2014"
##
##
## [[2]]
## [[2]]$reviewerID
## [1] "ASY55RVNIL0UD"
##
## [[2]]$asin
## [1] "120401325X"
##
## [[2]]$reviewerName
## [1] "emily l."
##
## [[2]]$helpful
## [1] 0 0
##
## [[2]]$reviewText
## [1] "These stickers work like the review says they do. They stick on great and they stay on the phone. They are super stylish and I can share them with my sister. :)"
##
## [[2]]$overall
## [1] 5
##
## [[2]]$summary
## [1] "Really great product."
##
## [[2]]$unixReviewTime
## [1] 1389657600
##
## [[2]]$reviewTime
## [1] "01 14, 2014"
##
##
## [[3]]
## [[3]]$reviewerID
## [1] "A2TMXE2AFO7ONB"
##
## [[3]]$asin
## [1] "120401325X"
##
## [[3]]$reviewerName
## [1] "Erica"
##
## [[3]]$helpful
## [1] 0 0
##
## [[3]]$reviewText
## [1] "These are awesome and make my phone look so stylish! I have only used one so far and have had it on for almost a year! CAN YOU BELIEVE THAT! ONE YEAR!! Great quality!"
##
## [[3]]$overall
## [1] 5
##
## [[3]]$summary
## [1] "LOVE LOVE LOVE"
##
## [[3]]$unixReviewTime
## [1] 1403740800
##
## [[3]]$reviewTime
## [1] "06 26, 2014"
##
##