HttpResponseMessage caching using redis

ghz 9months ago ⋅ 132 views

i want to get HttpResponseMessage from redis cache using dapr.

HttpResponseMessage doesn't any public constructor so I got error while casting json to HttpResponseMessage.

How can I save HttpResponseMessage object into redis and how can I get ?

Save operation:

HttpResponseMessage value = await MakeApiRequestCore(httpClient,callMethod,requestUri,accessToken,timeout,isResponseHttpResponseMessage, cancellationToken);
               
await _daprClient.SaveStateAsync<HttpResponseMessage>(redisStoreName, cacheKey, value, null, metadata, cancellationToken);

Get operation: (Error: System.NotSupportedException: Deserialization of types without a parameterless constructor, a singular parameterized constructor, or a parameterized constructor annotated with 'JsonConstructorAttribute' is not supported. Type 'System.Net.Http.HttpContent'. Path: $.content | LineNumber: 0 | BytePositionInLine: 28)

 var value = await _daprClient.GetStateAsync<HttpResponseMessage>(redisStoreName, cacheKey, cancellationToken: cancellationToken);

Answers

To save and retrieve HttpResponseMessage objects in Redis using Dapr, you'll need to serialize and deserialize them properly. Since HttpResponseMessage does not have a parameterless constructor and contains complex types like HttpContent, you'll need to handle serialization and deserialization manually.

Here's how you can achieve this:

  1. Serialize HttpResponseMessage to JSON: Serialize HttpResponseMessage to JSON format, including its properties such as status code, headers, and content. However, you can't serialize HttpContent directly, so you may need to extract relevant information (like content as string) and store it separately.

  2. Deserialize JSON back to HttpResponseMessage: When retrieving from Redis, deserialize the JSON string back to HttpResponseMessage. Reconstruct the HttpResponseMessage object, including its properties and content.

Here's an example of how you can achieve this:

using System.Net.Http;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;

public static class DaprHelper
{
    public static async Task SaveHttpResponseMessageAsync(IDaprClient daprClient, string redisStoreName, string cacheKey, HttpResponseMessage response, CancellationToken cancellationToken)
    {
        var serializedResponse = SerializeHttpResponseMessage(response);
        await daprClient.SaveStateAsync(redisStoreName, cacheKey, serializedResponse, cancellationToken: cancellationToken);
    }

    public static async Task<HttpResponseMessage> GetHttpResponseMessageAsync(IDaprClient daprClient, string redisStoreName, string cacheKey, CancellationToken cancellationToken)
    {
        var serializedResponse = await daprClient.GetStateAsync<string>(redisStoreName, cacheKey, cancellationToken: cancellationToken);
        return DeserializeHttpResponseMessage(serializedResponse);
    }

    private static string SerializeHttpResponseMessage(HttpResponseMessage response)
    {
        var responseDto = new HttpResponseMessageDto
        {
            StatusCode = (int)response.StatusCode,
            Headers = response.Headers,
            // Serialize content separately (example: as string)
            Content = response.Content != null ? await response.Content.ReadAsStringAsync() : null
        };
        return JsonSerializer.Serialize(responseDto);
    }

    private static HttpResponseMessage DeserializeHttpResponseMessage(string serializedResponse)
    {
        var responseDto = JsonSerializer.Deserialize<HttpResponseMessageDto>(serializedResponse);
        var response = new HttpResponseMessage((System.Net.HttpStatusCode)responseDto.StatusCode);
        response.Headers.Clear();
        foreach (var header in responseDto.Headers)
        {
            response.Headers.TryAddWithoutValidation(header.Key, header.Value.ToArray());
        }
        // Reconstruct content (example: from string)
        if (!string.IsNullOrEmpty(responseDto.Content))
        {
            response.Content = new StringContent(responseDto.Content);
        }
        return response;
    }

    // DTO class to serialize HttpResponseMessage
    private class HttpResponseMessageDto
    {
        public int StatusCode { get; set; }
        public IDictionary<string, IEnumerable<string>> Headers { get; set; }
        public string Content { get; set; }
    }
}

In this code:

  • SerializeHttpResponseMessage: Serializes HttpResponseMessage into a DTO object with status code, headers, and serialized content.
  • DeserializeHttpResponseMessage: Deserializes DTO object back into HttpResponseMessage.
  • SaveHttpResponseMessageAsync: Serializes and saves HttpResponseMessage to Redis.
  • GetHttpResponseMessageAsync: Retrieves serialized response from Redis and deserializes it back to HttpResponseMessage.

Make sure to replace IDaprClient, redisStoreName, cacheKey, and any other relevant types with their actual implementations in your codebase. Additionally, customize content serialization and deserialization as needed based on your requirements.

#redis