My code for JSON parsing:
// Store incoming data into a string
NSString *jsonString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
// Create a dictionary from the JSON string
NSDictionary *results = [jsonString JSONValue];
NSLog(#"%#",jsonString);
When I debug the code I am getting the jsonString but getting 0 key value pairs.
And Error as:
-JSONValue failed. Error trace is: (
"Error Domain=org.brautaset.JSON.ErrorDomain Code=5 \"Unescaped control character '0x0'\" UserInfo=0x4d2e030
{NSLocalizedDescription=Unescaped control character '0x0'}",
"Error Domain=org.brautaset.JSON.ErrorDomain Code=3 \"Object value expected for key: id\" UserInfo=0x4d2e130 {NSUnderlyingError=0x4d2e090
\"Unescaped control character '0x0'\", NSLocalizedDescription=Object
value expected for key: id}",
"Error Domain=org.brautaset.JSON.ErrorDomain Code=3 \"Expected value while parsing array\" UserInfo=0x4d2e180
{NSUnderlyingError=0x4d2e110 \"Object value expected for key: id\",
NSLocalizedDescription=Expected value while parsing array}",
"Error Domain=org.brautaset.JSON.ErrorDomain Code=3 \"Object value expected for key: predictions\" UserInfo=0x4d2e250
{NSUnderlyingError=0x4d2e210 \"Expected value while parsing array\",
NSLocalizedDescription=Object value expected for key: predictions}"
Use JSON validator to validate your string whether that is a valid JSON.
Related
i try to construct JSON with string that contains "\n" in it like this :
ver_str= 'Package ID: version_1234\nBuild\nnumber: 154\nBuilt\n'
proj_ver_str = 'Version_123'
comb = '{"r_content": {0}, "s_version": {1}}'.format(ver_str,proj_ver_str)
json_content = json.loads()
d =json.dumps(json_content )
getting this error:
exec(compile(contents+"\n", file, 'exec'), glob, loc)
File "C:/Dev/python/new_tester/simple_main.py", line 18, in <module>
comb = '{"r_content": {0}, "s_version": {1}}'.format(ver_str,proj_ver_str)
KeyError: '"r_content"'
The error arises not because of newlines in your values, but because of { and } characters in your format string other than the placeholders {0} and {1}. If you want to have an actual { or a } character in your string, double them.
Try replacing the line
comb = '{"r_content": {0}, "s_version": {1}}'.format(ver_str,proj_ver_str)
with
comb = '{{"r_content": {0}, "s_version": {1}}}'.format(ver_str,proj_ver_str)
However, this will give you a different error on the next line, loads() missing 1 required positional argument: 's'. This is because you presumably forgot to pass comb to json.loads().
Replacing json.loads() with json.loads(comb) gives you another error: json.decoder.JSONDecodeError: Expecting value: line 1 column 15 (char 14). This tells you that you've given json.loads malformed JSON to parse. If you print out the value of comb, you see the following:
{"r_content": Package ID: version_1234
Build
number: 154
Built
, "s_version": Version_123}
This isn't valid JSON, because the string values aren't surrounded by quotes. So a JSON parsing error is to be expected.
At this point, let's take a look at what your code is doing and what you seem to want it to do. It seems you want to construct a JSON string from your data, but your code puts together a JSON string from your data, parses it to a dict and then formats it back as a JSON string.
If you want to create a JSON string from your data, it's far simpler to create a dict with your values and use json.dumps on that:
d = json.dumps({"r_content": ver_str, "s_version": proj_ver_str})
I want to create an endpoint that receives JSON data and should parse it as an array of strings.
POST /
{
"keys": ["foo", "bar"]
}
I'm running into problems with the type system. This is what I tried (.as(Array(String))) but it does not compile:
require "kemal"
def print_keys(keys : Array(String))
puts "Got keys: #{keys}"
end
post "/" do |env|
keys = env.params.json["keys"].as(Array(String)) # <-- ERROR
print_keys(keys)
end
Kemal.run
The error message is:
8 | keys = env.params.json["keys"].as(Array(String)) # <-- ERROR
^
Error: can't cast (Array(JSON::Any) | Bool | Float64 | Hash(String, JSON::Any) | Int64 | String | Nil) to Array(String)
If I change the code to parse not Array(String) but instead String, it compiles without problems. Why does it make a difference in the .as method that the type is Array(String) instead of String?
How can the code be changed to parse arrays of strings?
I found an example in the documentation, which uses JSON.mapping. In my concrete example, it could be written as follows:
require "kemal"
def print_keys(keys : Array(String))
puts "Got keys: #{keys}"
end
class KeyMappings
JSON.mapping({
keys: Array(String)
})
end
post "/" do |env|
json = KeyMappings.from_json env.request.body.not_nil!
print_keys(json.keys)
end
Kemal.run
I have a server that returns requests in a JSON format. When trying to parse the data I always get "trailing characters" error. This happens only when getting the JSON from postman
let type_of_request = parsed_request[1];
let content_of_msg: Vec<&str> = msg_from_client.split("\r\n\r\n").collect();
println!("{}", content_of_msg[1]);
// Will print "{"username":"user","password":"password","email":"dwadwad"}"
let res: serde_json::Value = serde_json::from_str(content_of_msg[1]).unwrap();
println!("The username is: {}", res["username"]);
when getting the data from postman this happens:
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error("trailing characters", line: 1, column: 60)', src\libcore\result.rs:997:5
but when having the string inside Rust:
let j = "{\"username\":\"user\",\"password\":\"password\",\"email\":\"dwadwad\"}";
let res: serde_json::Value = serde_json::from_str(j).unwrap();
println!("The username is: {}", res["username"]);
it works like a charm:
The username is: "user"
EDIT: Apparently as I read the message into a buffer and turned it into a string it saved all the NULL characters the buffer had which are of course the trailing characters.
Looking at the serde json code, one finds the following comment above the relevant ErrorCode enum element:
/// JSON has non-whitespace trailing characters after the value.
TrailingCharacters,
So as the error code implies, you've got some trailing character which is not whitespace. In your snippet, you say:
println!("{}", content_of_msg[1]);
// Will print "{"username":"user","password":"password","email":"dwadwad"}"
If you literally copy and pasted the printed output here, I'd note that I wouldn't expect the output to be wrapped in the leading and trailing quotation marks. Did you include these yourself or were they part of what was printed? If they were printed, I suspect that's the source of your problem.
Edit:
In fact, I can nearly recreate this using a raw string with leading/trailing quotation marks in Rust:
extern crate serde_json;
#[cfg(test)]
mod tests {
#[test]
fn test_serde() {
let s =
r#""{"username":"user","password":"password","email":"dwadwad"}""#;
println!("{}", s);
let _res: serde_json::Value = serde_json::from_str(s).unwrap();
}
}
Running it via cargo test yields:
test tests::test_serde ... FAILED
failures:
---- tests::test_serde stdout ----
"{"username":"user","password":"password","email":"dwadwad"}"
thread 'tests::test_serde' panicked at 'called `Result::unwrap()` on an `Err` value: Error("trailing characters", line: 1, column: 4)', src/libcore/result.rs:997:5
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
failures:
tests::test_serde
Note that my printed output also includes leading/trailing quotation marks and I also get a TrailingCharacter error, albeit at a different column.
Edit 2:
Based on your comment that you've added the wrapping quotations yourself, you've got a known good string (the one you've defined in Rust), and one which you believe should match it but doesn't (the one from Postman).
This is a data problem and so we should examine the data. You can adapt the below code to check the good string against the other:
#[test]
fn test_str_comp() {
// known good string we'll compare against
let good =
r#"{"username":"user","password":"password","email":"dwadwad"}"#;
// lengthened string, additional characters
// also n and a in username are transposed
let bad =
r#"{"useranme":"user","password":"password","email":"dwadwad"}abc"#;
let good_size = good.chars().count();
let bad_size = bad.chars().count();
for (idx, (c1, c2)) in (0..)
.zip(good.chars().zip(bad.chars()))
.filter(|(_, (c1, c2))| c1 != c2)
{
println!(
"Strings differ at index {}: (good: `{}`, bad: `{}`)",
idx, c1, c2
);
}
if good_size < bad_size {
let trailing = bad.chars().skip(good_size);
println!(
"bad string contains extra characters: `{}`",
trailing.collect::<String>()
);
} else if good_size > bad_size {
let trailing = good.chars().skip(bad_size);
println!(
"good string contains extra characters: `{}`",
trailing.collect::<String>()
);
}
assert!(false);
}
For my example, this yields the failure:
test tests::test_str_comp ... FAILED
failures:
---- tests::test_str_comp stdout ----
Strings differ at index 6: (good: `n`, bad: `a`)
Strings differ at index 7: (good: `a`, bad: `n`)
bad string contains extra characters: `abc`
thread 'tests::test_str_comp' panicked at 'assertion failed: false', src/lib.rs:52:9
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
failures:
tests::test_str_comp
I'm trying to send a dict to javascript via port for storing the value in localStorage, and retrieve it next time the Elm app starts via flag.
Below code snippets show the dict sent as well as the raw json value received through flag. The Json decoding fails showing the error message at the bottom.
The issue seems to be the extra backslashes (as in \"{\\"Left\\") contained in the raw flag value. Interestingly, console.log shows that the flag value passed by javascript is "dict1:{"Left":"fullHeightVerticalCenter","Right":"fullHeightVerticalCenter","_default":"fullHeightVerticalBottom"}"as intended, so the extra backslashes seem to be added by Elm, but I can't figure out why. Also, I'd be interested to find out a better way to achieve passing a dict to and from javascript.
import Json.Decode as JD
import Json.Encode as JE
dict1 = Dict.fromList[("_default", "fullHeightVerticalBottom")
, ("Left", "fullHeightVerticalCenter")
, ("Right", "fullHeightVerticalCenter")]
type alias FlagsJEValue =
{dict1: String}
port setStorage : FlagsJEValue -> Cmd msg
-- inside Update function Cmd
setStorage {dict1 = JE.encode 0 (dictEncoder JE.string model.dict1)}
dictEncoder enc dict =
Dict.toList dict
|> List.map (\(k,v) -> (k, enc v))
|> JE.object
--
type alias Flags =
{dict1: Dict String String}
flagsDecoder : Decoder Flags
flagsDecoder =
JD.succeed Flags
|> required "dict1" (JD.dict JD.string)
-- inside `init`
case JD.decodeValue MyDecoders.flagsDecoder raw_flags of
Err e ->
_ = Debug.log "raw flag value" (Debug.toString (JE.encode 2 raw_flags) )
_ = Debug.log "flags error msg" (Debug.toString e)
... omitted ...
Ok flags ->
... omitted ...
-- raw flag value
"{\n \"dict1\": \"{\\\"Left\\\":\\\"fullHeightVerticalCenter\\\",\\\"Right\\\":\\\"fullHeightVerticalCenter\\\",\\\"_default\\\":\\\"fullHeightVerticalBottom\\\"}\"\n}"
--flags error msg
"Failure \"Json.Decode.oneOf failed in the following 2 ways:\\n\\n\\n\\n
(1) Problem with the given value:\\n \\n \\\"{\\\\\\\"Left\\\\\\\":\\\\\\\"fullHeightVerticalCenter\\\\\\\",\\\\\\\"Right\\\\\\\":\\\\\\\"fullHeightVerticalCenter\\\\\\\",\\\\\\\"_default\\\\\\\":\\\\\\\"fullHeightVerticalBottom\\\\\\\"}\\\"\\n \\n Expecting an OBJECT\\n\\n\\n\\n
(2) Problem with the given value:\\n \\n \\\"{\\\\\\\"Left\\\\\\\":\\\\\\\"fullHeightVerticalCenter\\\\\\\",\\\\\\\"Right\\\\\\\":\\\\\\\"fullHeightVerticalCenter\\\\\\\",\\\\\\\"_default\\\\\\\":\\\\\\\"fullHeightVerticalBottom\\\\\\\"}\\\"\\n \\n Expecting null\" <internals>”
You don't need to use JE.encode there.
You can just use your dictEncoder to produce a Json.Encode.Value and pass that directly to setStorage.
The problem you're encountering it that you've encoded the dict to a json string (using JE.encode) and then sent that string over a port and the port has encoded that string as json again. You see extra slashes because the json string is double encoded.
I get this error when I try to retrieve items from Parse.com
In 10 attempts it failed around 6 times.
PFQuery *query = [PFQuery queryWithClassName:#"ServiceCatalogue"];
items = [[NSMutableArray alloc] init];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
NSLog(#"ServiceCatalogue retrieved");
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];
And getting error:
"Error: Error Domain=NSCocoaErrorDomain Code=3840 "The operation
couldn’t be completed. (Cocoa error 3840.)" (JSON text did not start
with array or object and option to allow fragments not set.)
UserInfo=0x7fcfbaadc480 {NSDebugDescription=JSON text did not start
with array or object and option to allow fragments not set.} {
NSDebugDescription = "JSON text did not start with array or object and option to allow fragments not set.";
}"
As indicated in this status report from Parse, it looks like their servers were creating an elevated number of errors.
2nd October 2015 - Elevated Error Rates - Incident Report for Parse