feat: Add Request::get_file_multi_value func. (#1495)

Support to get multiple values of a key.

perf: Rename function names, variable names etc.

httplib.h

@@ -454,6 +454,7 @@ struct Request {
 
   bool has_file(const std::string &key) const;
   MultipartFormData get_file_value(const std::string &key) const;
+  std::vector<MultipartFormData> get_file_values(const std::string &key) const;
 
   // private members...
   size_t redirect_count_ = CPPHTTPLIB_REDIRECT_MAX_COUNT;
@@ -4690,6 +4691,15 @@ inline MultipartFormData Request::get_file_value(const std::string &key) const {
   return MultipartFormData();
 }
 
+inline std::vector<MultipartFormData> Request::get_file_values(const std::string &key) const {
+   std::vector<MultipartFormData> values;
+   auto rng = files.equal_range(key);
+   for (auto it = rng.first; it != rng.second; it++) {
+       values.push_back(it->second);
+   }
+   return values;
+}
+
 // Response implementation
 inline bool Response::has_header(const std::string &key) const {
   return headers.find(key) != headers.end();

test/test.cc

@@ -1767,6 +1767,40 @@ protected:
                   EXPECT_EQ("application/json  tmp-string", file.content_type);
                 }
               })
+        .Post("/multipart/multi_file_values",
+          [&](const Request &req, Response & /*res*/) {
+              EXPECT_EQ(5u, req.files.size());
+              ASSERT_TRUE(!req.has_file("???"));
+              ASSERT_TRUE(req.body.empty());
+
+              {
+                  const auto &text_value = req.get_file_values("text");
+                  EXPECT_EQ(text_value.size(), 1);
+                  auto &text = text_value[0];
+                  EXPECT_TRUE(text.filename.empty());
+                  EXPECT_EQ("defalut text", text.content);
+              }
+              {
+                const auto &text1_values = req.get_file_values("multi_text1");
+                EXPECT_EQ(text1_values.size(), 2);
+                EXPECT_EQ("aaaaa", text1_values[0].content);
+                EXPECT_EQ("bbbbb", text1_values[1].content);
+              }
+
+              {
+                const auto &file1_values = req.get_file_values("multi_file1");
+                EXPECT_EQ(file1_values.size(), 2);
+                auto file1 = file1_values[0];
+                EXPECT_EQ(file1.filename, "hello.txt");
+                EXPECT_EQ(file1.content_type, "text/plain");
+                EXPECT_EQ("h\ne\n\nl\nl\no\n", file1.content);
+
+                auto file2 = file1_values[1];
+                EXPECT_EQ(file2.filename, "world.json");
+                EXPECT_EQ(file2.content_type, "application/json");
+                EXPECT_EQ("{\n  \"world\", true\n}\n", file2.content);
+              }
+          })
         .Post("/empty",
               [&](const Request &req, Response &res) {
                 EXPECT_EQ(req.body, "");
@@ -2611,6 +2645,23 @@ TEST_F(ServerTest, MultipartFormData) {
   EXPECT_EQ(200, res->status);
 }
 
+TEST_F(ServerTest, MultipartFormDataMultiFileValues) {
+  MultipartFormDataItems items = {
+    {"text", "defalut text", "", ""},
+
+    {"multi_text1", "aaaaa", "", ""},
+    {"multi_text1", "bbbbb", "", ""},
+
+    {"multi_file1", "h\ne\n\nl\nl\no\n", "hello.txt", "text/plain"},
+    {"multi_file1", "{\n  \"world\", true\n}\n", "world.json", "application/json"},
+  };
+
+  auto res = cli_.Post("/multipart/multi_file_values", items);
+
+  ASSERT_TRUE(res);
+  EXPECT_EQ(200, res->status);
+}
+
 TEST_F(ServerTest, CaseInsensitiveHeaderName) {
   auto res = cli_.Get("/hi");
   ASSERT_TRUE(res);