System.Text.Json not working as expected (how Newtonsoft.json did) with [FromBody] WebApi parameter

[giammin]

before with Newtonsoft.json when calling a webapi like this

 [HttpPost]
public async Task<ActionResult> Post([FromBody]string someValue)

this worked:

curl -H "Content-Type:application/json" https://localhost:5000/api/controller-X POST -d "'dsfdsafasf'" -v

now with System.Text.Json there are no way to pass a simple string as a parameter.

I tried various combinatin like {"someValue":"fsdfsdfsdf"} or {'someValue':'fsdfsdfsdf'} or someValue'=asdfsdfsdf but without success

[ericstj]

@pranavkm @rynowak does this sound right? I would have expected that MVC has a fast path for this.

FWIW, the following worked for me: var str = JsonSerializer.Deserialize<string>("\"hello world\"");
Perhaps you can try using double-quotes in your post command?

[pranavkm]

@ericstj MVC doesn't special case deserializing a string value, it pretty much passes the request Stream as-is to the input.

@giammin you want to pass a JSON string token to MVC. JSON strings require that be double quoted - see http://www.json.org. Newtonsoft.Json was a bit more lax and allowed JSON (double quoted strings) and JavaScript strings (single quoted strings) which explains why -d "'dsfdsafasf'" works there. System.Text.Json is true to the spec which is why your binding's failing.

On my machine, I can get curl to work correctly if I author the call to curl like so:

curl -H "Content-Type:application/json" https://localhost:5000/api/controller-X POST -d "\"dsfdsafasf\"" -v

I used this https://stackoverflow.com/a/15828662 as my source to figure out how to author this correctly. You should use this to figure out what works best for your OS \ shell combination.

[giammin]

@pranavkm thanks for you reply.
i already tried different quotes and escaping and I did some further tests but i always get this error:

"'\' is an invalid start of a value. Path: $ | LineNumber: 0 | BytePositionInLine: 0."

and if I try something like:

curl -H "Content-Type:application/json" https://localhost:5000/api/controller -X POST -d "{\"someValue\":\"dsfjlsdajf\"}" -v

i get:

"The JSON value could not be converted to System.String. Path: $ | LineNumber: 0 | BytePositionInLine: 1."

[giammin]

i resolved...

the problem was powershell

adding --% resolved the issue https://stackoverflow.com/a/24750582/921690