Implemented missing API for issue #366: No Retrieve file content api (#367)

Author: costescuandrei

client/src/main/java/com/theokanning/openai/client/OpenAiApi.java

@@ -89,6 +89,10 @@ public interface OpenAiApi {
     @GET("/v1/files/{file_id}")
     Single<File> retrieveFile(@Path("file_id") String fileId);
 
+    @Streaming
+    @GET("/v1/files/{file_id}/content")
+    Single<ResponseBody> retrieveFileContent(@Path("file_id") String fileId);
+
     @POST("/v1/fine_tuning/jobs")
     Single<FineTuningJob> createFineTuningJob(@Body FineTuningJobRequest request);
 

service/src/main/java/com/theokanning/openai/service/OpenAiService.java

@@ -173,6 +173,10 @@ public File retrieveFile(String fileId) {
         return execute(api.retrieveFile(fileId));
     }
 
+    public ResponseBody retrieveFileContent(String fileId) {
+        return execute(api.retrieveFileContent(fileId));
+    }
+
     public FineTuningJob createFineTuningJob(FineTuningJobRequest request) {
         return execute(api.createFineTuningJob(request));
     }

service/src/test/java/com/theokanning/openai/service/FileTest.java

@@ -7,6 +7,9 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.TestMethodOrder;
 
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
@@ -52,6 +55,13 @@ void retrieveFile() {
 
     @Test
     @Order(4)
+    void retrieveFileContent() throws IOException {
+        String fileBytesToString = service.retrieveFileContent(fileId).string();
+        assertEquals(Files.readString(Path.of(filePath)), fileBytesToString);
+    }
+
+    @Test
+    @Order(5)
     void deleteFile() {
         DeleteResult result = service.deleteFile(fileId);
         assertTrue(result.isDeleted());