I have a JSON string in Swift 5 that is like this:
var text = """
{"ops": [{"insert": "Hello World!\n"},{"attributes": {"bold": true},"insert": "bold"},{"insert": "What if the "}, {"attributes": {"italic": true},"insert": "italic"}, {"insert": " text was awesome?\n\n"} ]}
"""
I pass that to a WKWebView where it is parsed with JSON.parse(text) so it can be rendered. At present, the JS complains that it's invalid. But if I manually edit the original string and replace all the \n with \\n, it works.
I need to turn \n into \\n programmatically and come out with a string on the other end.
I've tried this:
let raw = #"\#(text)"#
let ready = raw.replacingOccurrences(of: "\n", with: "\\n")
But it treats the newline characters as characters instead of as raw string elements.
It seems like this should be easy, but I can't see what I'm missing. Any ideas?
I found a solution to this. It isn't necessarily an answer to my question, but it avoids the issue altogether.
Prior to sending the JSON data to the Javascript in the WKWebView, I encode it to a string using Base64 encoding. This eliminates the need to worry about escaping characters and such. It works great. :)
Related
We use Freemarker to transform one JSON to another. The input JSON is something like this:
{"k1": "a", "k2":"line1. \n line2"}
Post using the Freemarker template, the JSON is converted to:
{ \n\n "p1": "a", \n\n "p2": "line1. \n line2"}
Here is the logic we use to do the transformation
final Map<String, Object> input = JsonConverter.convertFromJson(input, Map.class);
final Template template = freeMarkerConfiguration.getTemplate("Template1.ftl");
final Writer out = new StringWriter();
template.process(input, out);
out.flush();
final String newlineFilteredResult = new JSONObject(out.toString).toString();
The conversion to JSON object fails due to a newline character inside a string for key k2 and gives the following exception:
Caused by: org.json.JSONException: Unterminated string at ...
I tried using the following but nothing works:
1. JSONObject.quote
2. JSONValue.escape
3. out.toString().replaceAll("[\n\r]+", "\\n");
I get the following exception due to the newline characters at the beginning as well:
Caused by: org.json.JSONException: Missing value at 1 [character 2 line 1]
Could someone please point me in the correct direction.
Edit
After further clarification from OP he had "${key}": "${value}" in his freemarker template and ${value} could contain line brakes. The solution in this case is to use ${value?json_string}.
Starting from FreeMarker 2.3.32 you can write "${key}": ${value?c} instead of "${key}": "${value}", because if the left-side of ?c is a string, now instead of failing, it quotes and escapes the string. Thus you don't even have to know if the left-side is a number/boolean, which must not be quoted (and ?c won't quote them), or a string, which must be quoted, as it's automatic.
Also, if the left-value is known to be missing/null sometimes, them ?cn will handle that case by printing a null literal.
Also, check out the c_format setting for best results, but by default string formatting is JSON compatible, so using ?c will be an improvement even without setting that.
So I have some json that looks like this, which I got after taking it out of some other json by doing response.body.to_json:
{\n \"access_token\": \"<some_access_token>\",\n \"token_type\": \"Bearer\",\n \"expires_in\": 3600,\n \"id_token\": \<some_token>\"\n}\n"
I want to pull out the access_token, so I do
to_return = {token: responseJson[:access_token]}
but this gives me a
TypeError: no implicit conversion of Symbol into Integer
Why? How do I get my access token out? Why are there random backslashes everywhere?
to_json doesn't parse JSON - it does the complete opposite: it turns a ruby object into a string containing the JSON representation of that object is.
It's not clear from your question what response.body is. It could be a string, or depending on your http library it might have already been parsed for you.
If the latter then
response.body["access_token"]
Will be your token, if the former then try
JSON.parse(response.body)["access_token"]
Use with double quotes when calling access_token. Like below:
to_return = {token: responseJson["access_token"]}
Or backslashes are escaped delimiters and make sure you first parse JSON.
I'm attempting to read the following JSON file ("my_file.json") into R, which contains the following:
[{"id":"484","comment":"They call me "Bruce""}]
using the jsonlite package (0.9.12), the following fails:
library(jsonlite)
fromJSON(readLines('~/my_file.json'))
receiving an error:
"Error in parseJSON(txt) : lexical error: invalid char in json text.
84","comment":"They call me "Bruce""}]
(right here) ------^"
Here is the output from R escaping of the file:
readLines('~/my_file.json')
"[{\"id\":\"484\",\"comment\":\"They call me \"Bruce\"\"}]"
Removing the quotes around "Bruce" solves the problem, as in:
my_file.json
[{"id":"484","comment":"They call me Bruce"}]
But what is the issue with the escapement?
In R strings literals can be defined using single or double quotes.
e.g.
s1 <- 'hello'
s2 <- "world"
Of course, if you want to include double quotes inside a string literal defined using double quotes you need to escape (using backslash) the inner quotes, otherwise the R code parser won't be able to detect the end of the string correctly (the same holds for single quote).
e.g.
s1 <- "Hello, my name is \"John\""
If you print (using cat¹) this string on the console, or you write this string on a file you will get the actual "face" of the string, not the R literal representation, that is :
> cat("Hello, my name is \"John\"")
Hello, my name is "John"
The json parser, reads the actual "face" of the string, so, in your case json reads :
[{"id":"484","comment":"They call me "Bruce""}]
not (the R literal representation) :
"[{\"id\":\"484\",\"comment\":\"They call me \"Bruce\"\"}]"
That being said, also the json parser needs double-quotes escaping when you have quotes inside strings.
Hence, your string should be modified in this way :
[{"id":"484","comment":"They call me \"Bruce\""}]
If you simply modify your file by adding the backslashes you will be perfectly able to read the json.
Note that the corresponding R literal representation of that string would be :
"[{\"id\":\"484\",\"comment\":\"They call me \\\"Bruce\\\"\"}]"
in fact, this works :
> fromJSON("[{\"id\":\"484\",\"comment\":\"They call me \\\"Bruce\\\"\"}]")
id comment
1 484 They call me "Bruce"
¹
the default R print function (invoked also when you simply press ENTER on a value) returns the corresponding R string literal. If you want to print the actual string, you need to use print(quote=F,stringToPrint), or cat function.
EDIT (on #EngrStudent comment on the possibility to automatize quotes escaping) :
Json parser cannot do quotes escaping automatically.
I mean, try to put yourself in the computer's shoes and image you should parse this (unescaped) string as json: { "foo1" : " : "foo2" : "foo3" }
I see at least three possible escaping giving a valid json:
{ "foo1" : " : \"foo2\" : \"foo3" }
{ "foo1\" : " : "foo2\" : \"foo3" }
{ "foo1\" : \" : \"foo2" : "foo3" }
As you can see from this small example, escaping is really necessary to avoid ambiguities.
Maybe, if the string you want to escape has a really particular structure where you can recognize (without uncertainty) the double-quotes needing to be escaped, you can create your own automatic escaping procedure, but you need to start from scratch, because there's nothing built-in.
Im using nodejs to parse some JSON files and insert them into mongodb,the JSON in these files have invalid JSON characters like \n,\" etc ..
The thing that i dont understand is that if i tried to parse like :
console.log(JSON.parse('{"foo":"bar\n"}'))
i get
undefined:1
{"foo":"bar
but if i tried to parse the input from the file (The file has the same string {"foo":"bar\n"})like:
new lazy(fs.createReadStream("info.json"))
.lines
.forEach(function(line){
var line = line.toString();
console.log(JSON.parse(line));
}
);
every thing works fine , i want to know if this fine and its ok to parse the files i have, or i should replace all invalid JSON characters before i parse the files ,
and why is there a difference between the two.
Thanks
If you can read "\n" if your text file, then it's not an end of line but the \ character followed by a n.
\n in a JavaScript string literal adds an end of line and they're forbidden in JSON strings.
See json.org :
To put an end of line in a JSON string, you must escape it, which means you must escape the \ in a JavaScript string so that there's "\n" in the string received by JSON.parse :
console.log(JSON.parse('{"foo":"bar\\n"}'))
This would produce an object whose foo property value would contain an end of line :
I would like to parse an HTML document and print each of the paragraphs to a log file as an individual entry. So far I have:
let parseTextFile (path) =
let fileText = File.ReadAllText(path)
fileText.Split('<p>') |> Seq.iter (fun m -> logEmail(m))
But unfortunately for me string.Split does not do what I want here, it seems to exist to split a string by a single character delimiter. How can I split the file up using something more than a single character, it may be nice to have something more than just <p> as well because with just that I will have a </p> at the end of the paragraph. With a regex or some sort of complex matcher I could more specifically pick out everything between <p> tags.
Try using specific libraries for parsing html, for example HtmlAgilityPack.
As wmeyer said, you need to use a different overload of the .Split() method on strings. In fact, the code you posted won't even compile because '<p>' is not a string literal -- you need to use "<p>" instead (single quotes are for character literals).
Here's how to use the correct overload of .Split():
open System.IO
let parseTextFile path =
let fileText = File.ReadAllText path
fileText.Split ([| "<p>"; |], System.StringSplitOptions.RemoveEmptyEntries)
|> Seq.iter logEmail
For a quick test in F# Interactive:
> "First paragraph<p>Second paragraph.<p><p>Third paragraph.<p>"
.Split ([| "<p>"; |], System.StringSplitOptions.RemoveEmptyEntries);;
val it : string [] =
[|"First paragraph"; "Second paragraph."; "Third paragraph."|]
Finally, as #ntr said -- you're much, much better off using a library like the HTML Agility Pack for parsing HTML. Their parsers are very robust and will save you a lot of trouble.