How to pull multiple pages of results form the Azure query API (https://learn.microsoft.com/en-us/rest/api/cost-management/query/usage?tabs=HTTP)

azure_get_costs_per_scope.go

// define query
// import "github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/costmanagement/armcostmanagement"
query := armcostmanagement.QueryDefinition{
  Type:      to.Ptr(armcostmanagement.ExportTypeUsage),
  Timeframe: to.Ptr(armcostmanagement.TimeframeTypeCustom),
  TimePeriod: &armcostmanagement.QueryTimePeriod{
    From: start,
    To:   end,
  },
  Dataset: &armcostmanagement.QueryDataset{
    Granularity: to.Ptr(armcostmanagement.GranularityType("Monthly")),
    Aggregation: map[string]*armcostmanagement.QueryAggregation{
      "totalCost": {
        Name:     to.Ptr("PreTaxCost"),
        Function: to.Ptr(armcostmanagement.FunctionTypeSum),
      },
    },
    Grouping: []*armcostmanagement.QueryGrouping{{
      Type: to.Ptr(armcostmanagement.QueryColumnTypeDimension),
      Name: to.Ptr("SubscriptionId"),
    }},
  },
}

// stringify query
body, err := json.MarshalIndent(query, "", "  ")
if err != nil {
  return nil, err
}

// create http client
endpoint := microsoft.AzureADEndpoint("your-tenant-id") // from "golang.org/x/oauth2/microsoft"
endpoint.AuthStyle = oauth2.AuthStyleInParams
var azureConfig = &clientcredentials.Config{
  ClientID:     "your-client-id",
  ClientSecret: "your-client-secret",
  Scopes:       []string{"https://management.azure.com/.default"},
  TokenURL:     endpoint.TokenURL,
  AuthStyle:    oauth2.AuthStyleInParams,
}
client := azureConfig.Client()

res := armcostmanagement.QueryProperties{
  NextLink: to.Ptr("https://management.azure.com" + scope + "/providers/Microsoft.CostManagement/query?api-version=2021-10-01"),
  Columns:  nil,
  Rows:     [][]interface{}{},
}

// pull the data
for res.NextLink != nil && *res.NextLink != "" {
  host, err := url.ParseRequestURI(path)
  // TODO: error handling
  request, err := http.NewRequest(http.MethodPost, host.String(), body)
	// TODO: error handling
  request.Header.Set("Content-Type", "application/json")
  nextPage, err := client.Do(request)
  // TODO: error handling

  decoder := json.NewDecoder(nextPage.Body)
  data := &armcostmanagement.QueryClientUsageResponse{}
  if err = decoder.Decode(data); err != nil {
    return nil, err
  }
  res.Columns = data.Properties.Columns
  res.NextLink = data.Properties.NextLink
  res.Rows = append(res.Rows, data.Properties.Rows...) // at the end you have all rows inside this struct
}