问题描述
限时送ChatGPT账号..我正在尝试从我的 C# 应用程序调用此 API:https://ocr.space/OCRAPI
I'm trying to call this API from my C# app: https://ocr.space/OCRAPI
当我从 curl 调用它时,它工作正常:
When I call it from curl, it just works fine:
curl -k --form "file=@filename.jpg" --form "apikey=helloworld" --form "language=eng" https://api.ocr.space/Parse/Image
我是这样实现的:
[TestMethod]
public async Task Test_Curl_Call()
{
var client = new HttpClient();
String cur_dir = Directory.GetCurrentDirectory();
// Create the HttpContent for the form to be posted.
var requestContent = new FormUrlEncodedContent(new[] {
new KeyValuePair<string, string>( "file", "@filename.jpg"), //I also tried "filename.jpg"
new KeyValuePair<string, string>( "apikey", "helloworld" ),
new KeyValuePair<string, string>( "language", "eng")});
// Get the response.
HttpResponseMessage response = await client.PostAsync(
"https://api.ocr.space/Parse/Image",
requestContent);
// Get the response content.
HttpContent responseContent = response.Content;
// Get the stream of the content.
using (var reader = new StreamReader(await responseContent.ReadAsStreamAsync()))
{
// Write the output.
String result = await reader.ReadToEndAsync();
Console.WriteLine(result);
}
}
我得到了这个答案:
{
"ParsedResults":null,
"OCRExitCode":99,
"IsErroredOnProcessing":true,
"ErrorMessage":"No file uploaded or URL provided",
"ErrorDetails":"",
"ProcessingTimeInMilliseconds":"0"
}
有什么线索吗?
"file=@filename.jpg"
中的@ 字符是什么?
What's the @ character for in "file=@filename.jpg"
?
我将我的 filename.jpg 文件放在项目和测试项目的 bin/debug 目录中,并在调试模式下运行我的测试项目.
I put my filename.jpg file in the project and test project bin/debug directory and run my test project in debug mode.
所以我不认为错误指向文件不在预期的地方.我宁愿怀疑我的代码中存在语法错误.
So I don't think the error points to the file not being where expected. I'd rather suspect a syntax error in my code.
推荐答案
错误消息告诉您出了什么问题:
The error message is telling you what's wrong:
未上传文件或提供网址
您在代码中向服务发送了一个文件名,但这与给 curl 一个文件名不同.curl 足够聪明,可以读取文件并根据您的请求上传内容,但是在您的 C# 代码中,您必须自己完成.步骤将是:
You sent a filename to the service in your code, but that's not the same thing as giving curl a filename. curl is smart enough to read the file and upload the contents with your request, but in your C# code, you'll have to do that yourself. The steps will be:
从磁盘读取文件字节.创建一个包含两部分的多部分请求:API 密钥(helloworld")和文件字节.将此请求发布到 API.幸运的是,这很容易.这个问题演示了设置多部分的语法请求.
Fortunately, it's pretty easy. This question demonstrates the syntax to set up a multipart request.
此代码对我有用:
public async Task<string> TestOcrAsync(string filePath)
{
// Read the file bytes
var fileBytes = File.ReadAllBytes(filePath);
var fileName = Path.GetFileName(filePath);
// Set up the multipart request
var requestContent = new MultipartFormDataContent();
// Add the demo API key ("helloworld")
requestContent.Add(new StringContent("helloworld"), "apikey");
// Add the file content
var imageContent = new ByteArrayContent(fileBytes);
imageContent.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg");
requestContent.Add(imageContent, "file", fileName);
// POST to the API
var client = new HttpClient();
var response = await client.PostAsync("https://api.ocr.space/parse/image", requestContent);
return await response.Content.ReadAsStringAsync();
}
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