public async Task <string> SearchAsync(
BaseFhirApiOptions fhirApiOptions,
CancellationToken cancellationToken = default)
{
if (cancellationToken.IsCancellationRequested)
{
throw new OperationCanceledException();
}
Uri searchUri;
try
{
searchUri = CreateSearchUri(fhirApiOptions);
}
catch (Exception ex)
{
_logger.LogError("Create search Uri failed, Reason: '{reason}'", ex);
throw new FhirSearchException("Create search Uri failed", ex);
}
string accessToken = null;
if (fhirApiOptions.IsAccessTokenRequired)
{
try
{
if (_dataSource.Authentication == AuthenticationType.ManagedIdentity)
{
// Currently we support accessing FHIR server endpoints with Managed Identity.
// Obtaining access token against a resource uri only works with Azure API for FHIR now.
// To do: add configuration for OSS FHIR server endpoints.
// The thread-safe AzureServiceTokenProvider class caches the token in memory and retrieves it from Azure AD just before expiration.
// https://docs.microsoft.com/en-us/dotnet/api/overview/azure/service-to-service-authentication#using-the-library
accessToken = await _accessTokenProvider.GetAccessTokenAsync(_dataSource.FhirServerUrl, cancellationToken);
}
}
catch (Exception ex)
{
_logger.LogError("Get fhir server access token failed, Reason: '{reason}'", ex);
throw new FhirSearchException("Get fhir server access token failed", ex);
}
}
return(await GetResponseFromHttpRequestAsync(searchUri, accessToken, cancellationToken));
}
private Uri CreateSearchUri(BaseFhirApiOptions fhirApiOptions)
{
var serverUrl = _dataSource.FhirServerUrl;
var baseUri = new Uri(serverUrl);
var uri = new Uri(baseUri, fhirApiOptions.RelativeUri());
// the query parameters is null for metadata
if (fhirApiOptions.QueryParameters == null)
{
return(uri);
}
uri = uri.AddQueryString(fhirApiOptions.QueryParameters);
// add shared parameters _count & sort
var queryParameters = new List <KeyValuePair <string, string> >
{
new (FhirApiConstants.PageCountKey, FhirApiConstants.PageCount.ToString()),
new (FhirApiConstants.SortKey, FhirApiConstants.LastUpdatedKey),
};
public string Search(BaseFhirApiOptions fhirApiOptions)
{
if (fhirApiOptions.IsAccessTokenRequired && _dataSource.Authentication == AuthenticationType.ManagedIdentity)
{
_logger.LogError("Synchronous search doesn't support AccessToken, please use Asynchronous method SearchAsync() instead.");
throw new FhirSearchException(
"Synchronous search doesn't support AccessToken, please use Asynchronous method SearchAsync() instead.");
}
Uri searchUri;
try
{
searchUri = CreateSearchUri(fhirApiOptions);
}
catch (Exception ex)
{
_logger.LogError("Create search Uri failed, Reason: '{reason}'", ex);
throw new FhirSearchException("Create search Uri failed", ex);
}
return(GetResponseFromHttpRequest(searchUri));
}
