Getting 'Bad Request' and 'Invalid query definition' when calling Azure REST API

Question

I'm trying to call an Azure REST API endpoint to get information my daily usage cost.

I'm using Powershell 7.2 and here's my code:

$uri = 'https://management.azure.com/subscriptions/{subscription id}/providers/Microsoft.CostManagement/query?api-version=2021-10-01'
$token = '{generated bearer token string}'
$securetoken = ConvertTo-SecureString $token -AsPlainText -Force

$body = @{
    type = 'Usage'
    timeframe = 'MonthToDate'
    dataset = @{
        granularity = 'Daily'
        aggregation = @{
            totalCost = @{
                name = 'PreTaxCost'
                function = 'Sum'
            }
        }
        grouping = @(
            @{
                type = 'Dimension'
                name = 'ServiceName'
            }
        )
        
    }
}

$costresponse = Invoke-WebRequest -Uri $uri -Method Post -Authentication Bearer -Token $securetoken -Body $body
Write-Host $costresponse

Here's the request body example from the Microsoft documentation I'm trying to emulate:

{
  "type": "Usage",
  "timeframe": "TheLastMonth",
  "dataset": {
    "granularity": "None",
    "aggregation": {
      "totalCost": {
        "name": "PreTaxCost",
        "function": "Sum"
      }
    },
    "grouping": [
      {
        "type": "Dimension",
        "name": "ResourceGroup"
      }
    ]
  }
}

When I run the code I get this error message:

Line |
  27 |  … tresponse = Invoke-WebRequest -Uri $uri -Method Post -Authentication  …
     |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     | {"error":{"code":"BadRequest","message":"Invalid query definition: Missing dataset granularity; valid
     | values: 'Daily'.\r\n\r\n (Request ID: c6ead005-85b3-4ebe-9b46-........)"}}

I think the error has to do with the body syntax but I can't figure out what is the issue. I'm following this Microsoft documentation: https://learn.microsoft.com/en-us/rest/api/cost-management/query/usage

EDIT: I tried converting the body to JSON and adding a depth parameter like this:

$costresponse = Invoke-WebRequest -Uri $uri -Method Post -Authentication Bearer -Token $securetoken -Body ($body|ConvertTo-Json -Depth 5)

And now I get a slightly different error message:

Line |
  26 |  … tresponse = Invoke-WebRequest -Uri $uri -Method Post -Authentication  …
     |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     | {"error":{"code":"BadRequest","message":"Invalid query definition, Dataset is invalid or not supplied.
     | (Request ID: cf6a4b8f-88e8-4037-aa33-904......)"}}

Answer 1

I needed to add -ContentType 'application/json' to my Invoke-WebRequest function to get it to work. Thanks to @bluuf for the suggestion.