Batch Request Adapter

The batch request adapter bridges a list of public requests to the validation client. It maps the incoming requests to the provider's batch DTO using the batch request mapper, then forwards it to the same typed HttpClient used by the singular pipeline. Implement IBatchApiRequestAdapter<TRequest, TApiResponse>.

[SuppressMessage("Performance", "CA1812:Avoid uninstantiated internal classes", Justification = "Instantiated by DI container")]
internal sealed class BatchApiRequestAdapter : IBatchApiRequestAdapter<MyAddressValidationRequest, ApiResponse>
{
    private readonly MyAddressValidationClient _client;

    private readonly IBatchApiRequestMapper<MyAddressValidationRequest, ApiRequest> _requestMapper;

    public BatchApiRequestAdapter(MyAddressValidationClient client,
                                  IBatchApiRequestMapper<MyAddressValidationRequest, ApiRequest> requestMapper)
    {
        _client = client ?? throw new ArgumentNullException(nameof(client));
        _requestMapper = requestMapper ?? throw new ArgumentNullException(nameof(requestMapper));
    }

    public Task<ApiResponse?> ExecuteAsync(IReadOnlyList<MyAddressValidationRequest> requests, CancellationToken cancellationToken)
    {
        ApiRequest apiRequest = _requestMapper.Map(requests);
        return _client.ValidateAddressAsync(apiRequest, cancellationToken);
    }
}

Note

No new authentication or HTTP infrastructure is needed for batch support. The adapter reuses the same validation client and, transitively, the same BearerTokenDelegatingHandler<TClient> and resilience pipeline configured for the singular pipeline. If the provider's batch endpoint is a different URL or accepts a different request shape than the single-address endpoint, add a second method to the existing validation client rather than creating a separate typed HttpClient.

public Task<ApiResponse?> ValidateAddressesAsync(ApiRequest request, CancellationToken cancellationToken = default)
{
    ArgumentNullException.ThrowIfNull(request);
    return ValidateAddressesInternalAsync(request, cancellationToken);
}

private async Task<ApiResponse?> ValidateAddressesInternalAsync(ApiRequest request, CancellationToken cancellationToken)
{
    Uri requestUri = new(_options.Value.EndpointUri, "/v1/address/validate-batch");

    using HttpRequestMessage httpRequest = new(HttpMethod.Post, requestUri);
    httpRequest.Content = JsonContent.Create(request, MyApiRequestJsonSerializerContext.Default.ApiRequest);

    using HttpResponseMessage response = await _httpClient.SendAsync(httpRequest, cancellationToken).ConfigureAwait(false);
    if ( response.IsSuccessStatusCode )
    {
        return await response.Content.ReadFromJsonAsync(MyApiResponseJsonSerializerContext.Default.ApiResponse, cancellationToken)
                                     .ConfigureAwait(false);
    }

    ApiErrorResponse? errorResponse = await response.Content.ReadFromJsonAsync(MyApiResponseJsonSerializerContext.Default.ApiErrorResponse, cancellationToken)
                                                             .ConfigureAwait(false);
    return errorResponse is not null ? new ApiResponse { ErrorResponse = errorResponse } : null;
}

Note

It is not necessary for the batch request adapter to be internal, but it is strongly recommended if redistributing as a library.