Do you consider the JSON web response:
"A serialization error occurred"
to be valid or not?
Some validators accept it while others don't.
asked Nov 10, 2012 at 1:43
5 Answers
As for new JSON RFC, json, containing only single value is pretty valid.
A JSON text is a serialized value. Note that certain previous specifications of JSON constrained a JSON text to be an object or an array.
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1Yes, it is valid. Note that for better interoperability you can return a single element array:
[ "value" ]Commented Feb 12, 2015 at 13:55 -
For reasons of extensibility, one should always use an object, especially when dealing with a Rest API.– devopsCommented Jan 18, 2022 at 7:21
There's a change of heart on this between RFC4627 and RFC7159:
RFC4627:
A JSON text is a serialized object or array.
JSON-text = object / array
RFC7159:
A JSON text is a serialized value. Note that certain previous
specifications of JSON constrained a JSON text to be an object or an
array. Implementations that generate only objects or arrays where a
JSON text is called for will be interoperable in the sense that all
implementations will accept these as conforming JSON texts.JSON-text = ws value ws
No philosophical or practical justification is provided for this change of heart. The earlier version probably makes more sense as it consistently dictates that both a singe list element and a single map element (a pair or tuple) be contained. The second version allows only a single list element to be uncontained.
answered Aug 20, 2014 at 23:01
According to the grammar exposed in http://www.json.org/ (which references the Standard ECMA-262 3rd Edition - December 1999 par.5.1.5 The JSON Grammar) it's wrong:
The initial element must be:
and then a value can be a string:
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1Hi Tony, I did consult that page too, and I had the same understanding. But I wanted to ask the community since some sites (like the one I putted as reference) consider the single string value as a valid json response. Seeing the responses here just confirm that is does not make sense. Commented Nov 12, 2012 at 13:08
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1I tried that site and I agree with you it seems misleading. Usually I use jsonlint.com which is not accepting a string as a valid JSON: "Parse error on line 1: "ciao" ^ Expecting '{', '[' " . The error message is clear: it is expecting an Object or an Array.– Tony RadCommented Nov 12, 2012 at 15:56
From RFC4627:
A JSON text is a serialized object or array. JSON-text = object / array
IE, the root element has to be an object or array, and can't be a string value by itself.
I don't care if some validator accepts it. It's wrong. It's a question of good practice, Json format must be {"key": "value", .....}. If you consider that text Json, can work, but for the rest of programmer it's not a serious Json. If you use only that text, then you don't need Json.
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Not that simple. New specifications consider single values as valid JSON. Commented Feb 12, 2015 at 13:53
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3Consider the case of an JSON API, a very common case. When returning a 404 or other error how should the value be encoded in your world? I would also suggest that "serious Json" (surely you mean "serious JSON"?) is what the JSON spec defines. For the internet and the content type application/json that is RFC-7159 (tools.ietf.org/html/rfc7159) and it allows for a pure string, specifically: "JSON-text = ws value ws [...] A JSON value MUST be an object, array, number, or string, or one of the following three literal names: false null true". Commented Aug 1, 2015 at 9:33
A serialization error occurredbut"A serialization error occurred"