Re: Checking if a string is valid JSON
Re: Checking if a string is valid JSON
- Subject: Re: Checking if a string is valid JSON
- From: Saagar Jha <email@hidden>
- Date: Mon, 29 Jan 2018 13:30:05 -0800
Saagar Jha
> On Jan 29, 2018, at 13:25, Quincey Morris
> <email@hidden> wrote:
>
> On Jan 29, 2018, at 12:42 , Eric E. Dolecki <email@hidden> wrote:
>>
>> So this would do it?
>
> I would strongly recommend using JSONDecoder instead of JSONSerialization.
> The errors JSONDecoder throws are AFAIK more detailed than JSONSerialization,
> and will tell you the exact location in the string of any error you find.
Uhh…JSONDecoder swallows all of JSONSerialization’s errors and wraps it into
its own
<https://github.com/apple/swift/blob/e5fdc0955ce662bd929c7e1706d4a1f1d0f5d397/stdlib/public/SDK/Foundation/JSONEncoder.swift#L1097>.
I’m not sure this counts as “more detailed”.
>
> Also, FWIW, I beg you not to use this pattern (if you actually do, outside of
> this sample fragment):
>
>> let jsonData = jsonString.data(using: String.Encoding.utf8)
>> …
>> _ = try JSONSerialization.jsonObject(with: jsonData!)
>
>
> but do this instead:
>
>> let jsonData = jsonString.data(using: String.Encoding.utf8)!
>> …
>> _ = try JSONSerialization.jsonObject(with: jsonData)
>
>
> That is, don’t let optionals “escape” from the place where they first appear.
> If, in real code, you’re going to make the string decoding failure a handled
> error too, then this would of course become:
>
>> if let jsonData = jsonString.data(using: String.Encoding.utf8) {
>> …
>> …
>> _ = try JSONSerialization.jsonObject(with: jsonData)
>
>
> where the optional still doesn’t escape from its point of appearance.
>
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