Copying a simple JSON request body like the following in SLACK throws an error after using it in my request
{
“identifier”:“123abc”,
“mappings”:[
{
“a”: 1,
“b”: 2,
“c”: 3
}
]
}
I noticed when trying to convert this to ASCII that the '"' character before and after pasting this code in slack was a different unicode codepoint. Is this slacks doing? Or is this some conversion that is happening for them by virtue of their font or something?
" becomes appropriate left and right quotes ” “
Isn't it possible/preferable in most cases for them to save it in the unicode that I specified it in? Wouldn't it be better if a copy action went to the database and retrieved the actual unicode I began with or is this too slow for most people?
It’s a word processor. Word processors tend to use quote characters that are better for word processing. Never pass source code, including JSON, through a word processor.
When I create a string containing backslashes, they get duplicated:
>>> my_string = "why\does\it\happen?"
>>> my_string
'why\\does\\it\\happen?'
Why?
What you are seeing is the representation of my_string created by its __repr__() method. If you print it, you can see that you've actually got single backslashes, just as you intended:
>>> print(my_string)
why\does\it\happen?
The string below has three characters in it, not four:
>>> 'a\\b'
'a\\b'
>>> len('a\\b')
3
You can get the standard representation of a string (or any other object) with the repr() built-in function:
>>> print(repr(my_string))
'why\\does\\it\\happen?'
Python represents backslashes in strings as \\ because the backslash is an escape character - for instance, \n represents a newline, and \t represents a tab.
This can sometimes get you into trouble:
>>> print("this\text\is\not\what\it\seems")
this ext\is
ot\what\it\seems
Because of this, there needs to be a way to tell Python you really want the two characters \n rather than a newline, and you do that by escaping the backslash itself, with another one:
>>> print("this\\text\is\what\you\\need")
this\text\is\what\you\need
When Python returns the representation of a string, it plays safe, escaping all backslashes (even if they wouldn't otherwise be part of an escape sequence), and that's what you're seeing. However, the string itself contains only single backslashes.
More information about Python's string literals can be found at: String and Bytes literals in the Python documentation.
As Zero Piraeus's answer explains, using single backslashes like this (outside of raw string literals) is a bad idea.
But there's an additional problem: in the future, it will be an error to use an undefined escape sequence like \d, instead of meaning a literal backslash followed by a d. So, instead of just getting lucky that your string happened to use \d instead of \t so it did what you probably wanted, it will definitely not do what you want.
As of 3.6, it already raises a DeprecationWarning, although most people don't see those. It will become a SyntaxError in some future version.
In many other languages, including C, using a backslash that doesn't start an escape sequence means the backslash is ignored.
In a few languages, including Python, a backslash that doesn't start an escape sequence is a literal backslash.
In some languages, to avoid confusion about whether the language is C-like or Python-like, and to avoid the problem with \Foo working but \foo not working, a backslash that doesn't start an escape sequence is illegal.
The JSON specification states that control characters that must be escaped are only with codes from U+0000 to U+001F:
7. Strings
The representation of strings is similar to conventions used in the C
family of programming languages. A string begins and ends with
quotation marks. All Unicode characters may be placed within the
quotation marks, except for the characters that must be escaped:
quotation mark, reverse solidus, and the control characters (U+0000
through U+001F).
Main idea of escaping is to don't damage output when printing JSON document or message on terminal or paper.
But there other control characters like [DEL] from C0 and other control characters from C1 set (U+0080 through U+009F). Shouldn't be they also escaped in JSON strings?
From the JSON specification:
8. String and Character Issues
8.1. Character Encoding
JSON text SHALL be encoded in UTF-8, UTF-16, or UTF-32.
In UTF-8, all codepoints above 127 are encoded in multiple bytes. About half of those bytes are in the C1 control character range. So in order to avoid having those bytes in a UTF-8 encoded JSON string, all of those code points would need to be escaped. This effectively eliminates the use of UTF-8 and the JSON string might as well be encoded in ASCII. As ASCII is a subset of UTF-8 this is not disallowed by the standard. So if you are concerned with putting C1 control characters in the byte stream just escape them, but requiring every JSON representation to use ASCII would be wildly inefficient in anything but an english environment.
UTF-16 and UTF-32 could not possibly be parsed by something that uses the C1 (or even C0) control characters so the point is rather moot for those encodings.
How would I include the math symbol Pi in a JSON file? \p seems to be reserved in JSON.
{
"Text": "This is the symbol for the number Pi: $\pi$",
"Type": "A"
}
You need to escape the backslash "This is the symbol for the number Pi: $\\pi$". Otherwise, the string literal tries to interpret \p in the same way that it would interpret something like \n.
Here is my string
{
'user': {
'name': 'abc',
'fx': {
'message': {
'color': 'red'
},
'user': {
'color': 'blue'
}
}
},
'timestamp': '2013-10-04T08: 10: 41+0100',
'message': 'I'mABC..',
'nanotime': '19993363098581330'
}
Here the message contains single quotation mark, which is same as the quotation used in JSON. What I do is fill up a string from user inputs such as message. So, I need to escape those kind of special scenarios which breaks the code. But other than string replace, is there any way to make them escape but still allow HTML to process them back to the correct message?
I'm appalled by the presence of highly-upvoted misinformation on such a highly-viewed question about a basic topic.
JSON strings cannot be quoted with single quotes. The various versions of the spec (the original by Douglas Crockford, the ECMA version, and the IETF version) all state that strings must be quoted with double quotes. This is not a theoretical issue, nor a matter of opinion as the accepted answer currently suggests; any JSON parser in the real world will error out if you try to have it parse a single-quoted string.
Crockford's and ECMA's version even display the definition of a string using a pretty picture, which should make the point unambiguously clear:
The pretty picture also lists all of the legitimate escape sequences within a JSON string:
\"
\\
\/
\b
\f
\n
\r
\t
\u followed by four-hex-digits
Note that, contrary to the nonsense in some other answers here, \' is never a valid escape sequence in a JSON string. It doesn't need to be, because JSON strings are always double-quoted.
Finally, you shouldn't normally have to think about escaping characters yourself when programatically generating JSON (though of course you will when manually editing, say, a JSON-based config file). Instead, form the data structure you want to encode using whatever native map, array, string, number, boolean, and null types your language has, and then encode it to JSON with a JSON-encoding function. Such a function is probably built into whatever language you're using, like JavaScript's JSON.stringify, PHP's json_encode, or Python's json.dumps. If you're using a language that doesn't have such functionality built in, you can probably find a JSON parsing and encoding library to use. If you simply use language or library functions to convert things to and from JSON, you'll never even need to know JSON's escaping rules. This is what the misguided question asker here ought to have done.
A JSON string must be double-quoted, according to the specs, so you don't need to escape '.
If you have to use special character in your JSON string, you can escape it using \ character.
See this list of special character used in JSON :
\b Backspace (ascii code 08)
\f Form feed (ascii code 0C)
\n New line
\r Carriage return
\t Tab
\" Double quote
\\ Backslash character
However, even if it is totally contrary to the spec, the author could use \'.
This is bad because :
It IS contrary to the specs
It is no-longer JSON valid string
But it works, as you want it or not.
For new readers, always use a double quotes for your json strings.
Everyone is talking about how to escape ' in a '-quoted string literal. There's a much bigger issue here: single-quoted string literals aren't valid JSON. JSON is based on JavaScript, but it's not the same thing. If you're writing an object literal inside JavaScript code, fine; if you actually need JSON, you need to use ".
With double-quoted strings, you won't need to escape the '. (And if you did want a literal " in the string, you'd use \".)
Most of these answers either does not answer the question or is unnecessarily long in the explanation.
OK so JSON only uses double quotation marks, we get that!
I was trying to use JQuery AJAX to post JSON data to server and then later return that same information.
The best solution to the posted question I found was to use:
var d = {
name: 'whatever',
address: 'whatever',
DOB: '01/01/2001'
}
$.ajax({
type: "POST",
url: 'some/url',
dataType: 'json',
data: JSON.stringify(d),
...
}
This will escape the characters for you.
This was also suggested by Mark Amery, Great answer BTW
Hope this helps someone.
May be i am too late to the party but this will parse/escape single quote (don't want to get into a battle on parse vs escape)..
JSON.parse("\"'\"")
The answer the direct question:
To be safe, replace the required character with \u+4-digit-hex-value
Example:
If you want to escape the apostrophe ' replace with \u0027
D'Amico becomes D\u0027Amico
NICE REFERENCE:
http://es5.github.io/x7.html#x7.8.4
https://mathiasbynens.be/notes/javascript-escapes
Using template literals...
var json = `{"1440167924916":{"id":1440167924916,"type":"text","content":"It's a test!"}}`;
Use encodeURIComponent() to encode the string.
Eg.:
var product_list = encodeURIComponent(JSON.stringify(product_list));
You don't need to decode it since the web server automatically do the same.
To allow single quotes within doubule quoted string for the purpose of json, you double the single quote. {"X": "What's the question"} ==> {"X": "What''s the question"}
https://codereview.stackexchange.com/questions/69266/json-conversion-to-single-quotes
The \' sequence is invalid.
regarding AlexB's post:
\' Apostrophe or single quote
\" Double quote
escaping single quotes is only valid in single quoted json strings
escaping double quotes is only valid in double quoted json strings
example:
'Bart\'s car' -> valid
'Bart says \"Hi\"' -> invalid