PowerShell JSON Headers not Converting correctly

Question

I am using an API REST call, but the problem is that it for some reason is not passing the header value correctly. I am getting an error about it not converting from "System.String" to "System.Collections.IDictionary". The code is:

$Headers = New-Object 'System.Collections.Generic.Dictionary[[String],[String]]'

$Headers.Add('X-CENTRIFY-NATIVE-CLIENT', 'true')
$Headers.Add('Content-Type', 'application/json')

$Body = @{
    TenantId = 'ID'
    User = '[email protected]'
    Version = '1.0' 
} 

#$wr = Invoke-WebRequest -Method Post -Uri $url -Headers $Headers -Body $Body -Verbose  

Invoke-RestMethod -Uri "https://uri/Security/StartAuthentication" -Method Post  -Headers ($Headers | ConvertTo-Json -Compress) -UseBasicParsing -Body $Body

But when I execute I get this error (FQID):

Invoke-RestMethod : Cannot bind parameter 'Headers'. Cannot convert the "{
    "X-CENTRIFY-NATIVE-CLIENT":  "true",
    "Content-Type":  "application/json"
}" value of type "System.String" to type "System.Collections.IDictionary".
At line:31 char:109
+ ... tication" -Method Post  -Headers ($Headers1 | ConvertTo-Json) -UseBas ...
+                                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [Invoke-RestMethod], ParameterBindingException
    + FullyQualifiedErrorId : CannotConvertArgumentNoMessage,Microsoft.PowerShell.Commands.InvokeRestMethodCommand

I have tried my headers being like this as well:

$headers = @{

    'Content-Type'= 'application/json'
    'X-CENTRIFY-NATIVE-CLIENT'= 'true'
}

But I still get that same error. It is odd that it keeps complaining about this reference; This library is not native to PoSH. Is there a DLL I should load or is there a better way to go about this?

Remove ConvertTo-Json completely, just do -Headers $Headers — Mathias R. Jessen
– Mathias R. Jessen, Commented Mar 9, 2020 at 18:36

Mathias R. Jessen · Accepted Answer · 2020-03-09 18:43:56Z

3

The -Headers parameter expects a dictionary, not a json object.

Pass $Headers directly:

$uri = "https://uri/Security/StartAuthentication"
Invoke-RestMethod -Uri $uri -Method Post -Headers $Headers -UseBasicParsing -Body $Body

You can inspect parameter details with Get-Help:

PS > Get-Help Invoke-WebRequest -Parameter Headers

-Headers <IDictionary>

    Required?                    false
    Position?                    Named
    Accept pipeline input?       false
    Parameter set name           (All)
    Aliases                      None
    Dynamic?                     false

answered Mar 9, 2020 at 18:43

Mathias R. Jessen

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shadow2020 · Accepted Answer · 2020-03-09 18:57:23Z

0

I took the json conversion out of the header on your invoke restmethod. That part will need to be done on your payload $Body. Give this a try.

$Headers = @{}
$Headers.Add('X-CENTRIFY-NATIVE-CLIENT', 'true')
$Headers.Add('Content-Type', 'application/json')

$Body = @{
    TenantId = 'ID'
    User = '[email protected]'
    Version = '1.0' 
} 

$Body = ($Body | ConvertTo-Json)

#$wr = Invoke-WebRequest -Method Post -Uri $url -Headers $Headers -Body $Body -Verbose  

Invoke-RestMethod -Uri "https://uri/Security/StartAuthentication" -Method Post -Headers $Headers -UseBasicParsing -Body $Body

answered Mar 9, 2020 at 18:57

shadow2020

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