Powershell ConvertTo-JSON returning "nested" object - json

Question

I'm trying to make a POST request to my server. Everything was fine until I decided to convert my object to JSON. Here's my code:
$postParams = #{
Login = "JonSnow66";
Password = "LetItSnow";
Email = "Jon.Snow#wall.com";
Name = "Jon Snow";
Desc = "I know nothing";
BirthDate = "1572 2 16";
Img = Get-Content -Path ./PH_img.txt | Out-String;
Type = "Admin";
}
Invoke-WebRequest -Uri http://localhost:3000/api/add/user -Method POST -Body (ConvertTo-Json $postParams -Compress)
Instead of returning regular JSON object like:
{
"Login": "JonSnow66"
...
}
It returns:
{{
"Login": "JonSnow66",
"BirthDate": "1572 2 16",
"Desc": "I know nothing",
"Name": "Jon Snow",
"Type": "Admin",
"Password": "LetItSnow",
"Img": "/9j/4<BASE64>/Z\r\n",
"Email": "Jon.Snow#wall.com"
}: ""}
I'm just a powershell beginner.

Answer 1

I think you need to specify ContentType on Invoke-WebRequest to be 'application/json'. If you don't specify a content type and are performing a Post then I think the cmdlet assumes you are submitting a form by default, and that might explain the extra { } characters you are seeing in the result.
Here's the modified code:
Invoke-WebRequest -Uri 'http://localhost:3000/api/add/user' -Method POST -ContentType 'application/json' -Body (ConvertTo-Json $postParams -Compress)