tushar
Below is the json I get after encoding it using Jason
"{\"topic\": \"dummy_topic\", \"msg\": \"{\"fruit\":\"apple\",\"dish\":\"apple-pie\"}\"}"
I am trying to pass it as the body of the request while calling an API using HTTPoison , it gives me the json decode error
tried the same on terminal and I get below ,
iex(10)> var = "{\"topic\": \"dummy_topic\", \"msg\": \"{\"fruit\":\"apple\",\"dish\":\"apple-pie\"}\"}"
"{\"topic\": \"dummy_topic\", \"msg\": \"{\"fruit\":\"apple\",\"dish\":\"apple-pie\"}\"}"
iex(11)> Jason.decode(var)
{:error,
%Jason.DecodeError{
data: "{\"topic\": \"dummy_topic\", \"msg\": \"{\"fruit\":\"apple\",\"dish\":\"apple-pie\"}\"}",
position: 35,
token: nil
}}
Which is the exact same error I get when when I use HTTPoison ,
my expectation is I should be getting something like below when I use Jason.decode ,
%{
"topic" => "dummy_topic",
"msg" => %{"fruit" => "apple", "dish" => "apple-pie"}
}
Do you know where I am getting it wrong or what can be done to get the expected output ?
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NobbZ
You can’t decide it, because you encode it wrong, that’s what I am trying to tell you the whole time.
Have you tried my suggestions from Decoding Multi Level Json - #6 by NobbZ?
tushar
True but as is , the string causes a problem when I try to decode it using
Jason.decodeIts unable to find the inner map… , any way we can counter that problem and have my desired structure back from the json string , if you need the original Elixir map which I converted to Json and and want to have it back , let me know.
NobbZ
I thought you want msg to be a string containing JSON? Then of course you can not remove the wrapping quotes that make it a string.
tushar
"{\"topic\": \"dummy_topic\", \"msg\": \"{\"fruit\":\"apple\",\"dish\":\"apple-pie\"}\"}"→ This does not work"{\"topic\": \"dummy_topic\", \"msg\": {\"fruit\":\"apple\",\"dish\":\"apple-pie\"}}"→ This worksThe only difference between the strings is
"{\"topic\": \"dummy_topic\", \"msg\": *\"*{\"fruit\":\"apple\",\"dish\":\"apple-pie\"}*\"*}"The escape sequences causing problem are wrapped in *
Those two escape sequences if removed , makes it work fine.
Is there a way with Sigils I can choose to not have those escapes ? or I have to do string manipulation to have it working ?
NobbZ
These variants should both work. I’m not sure about exact quoting here, so it might be, that you need to wrap the interpolated value in another pair of quotes.
I prefer the first approach for readability.
tushar
Thanks @NobbZ ,
It was happening because of the sigil , I found it finally and solved it by replacing the body of the inner json into a String that would contain a place holder for it.
So my requirement here was the value of a key in the map would be another json , that json would also be derived from a map , I used
Jason.encodeto do this , it puts an escape\"before the starting braces ,and then after composing the body of the final json I used sigil (
~s) which had put another escape prefixing the escape , which was causing a problem duringJason.decodesince it was unable to find the start of the inner map.How I fixed it is in the final json I just put a placeholder
<body>and then replaced the body with theJason.encodeinner json string.With sigils is there a way to avoid escaping the escape characters to construct the right json that can be used flawlessly with
Jason.decodeNobbZ
That is where the error is, this matches exactly with what I said, the quotes aren’t escaped properly. The following should be valid:
Alternatively, you have to double escape in the
msgfield:I prefer the sigil approach for readability.
ityonemo
It’s in position 35, as the error states.
NobbZ
Due to the doublequotes in the value of
msgbeeing improperly escaped, you don’t have valid JSON.