added .add_file()

Cargo.toml

@@ -13,5 +13,5 @@ serde = {version = "1.0.92", features = ["derive"] }
 lazy_static = "1.3"
 apply = "0.2.2"
 derive_more = "0.15.0"
-
 tokio = "0.1"
+bytes = "0.4.12"

src/core/requests/form_builder.rs

@@ -2,6 +2,7 @@ use reqwest::r#async::multipart::Form;
 use serde::Serialize;
 use crate::core::types::ParseMode;
 use crate::core::requests::ChatId;
+use crate::core::requests::utils;
 
 /// This is a convenient struct that builds `reqwest::r#async::multipart::Form`
 /// from scratch.
@@ -37,6 +38,12 @@ impl FormBuilder {
         }
     }
 
+    pub fn add_file(self, name: &str, path_to_file: &String) -> Self {
+        Self {
+            form: self.form.part(name.to_owned(), utils::file_to_part(path_to_file))
+        }
+    }
+
     pub fn build(self) -> Form {
         self.form
     }
@@ -85,3 +92,9 @@ impl ToFormValue for ChatId {
         }
     }
 }
+
+impl ToFormValue for String {
+    fn to_form_value(&self) -> String {
+        self.to_owned()
+    }
+}

src/core/requests/utils.rs

@@ -0,0 +1,27 @@
+use tokio::codec::FramedRead;
+use std::fs::File;
+use bytes::{Bytes, BytesMut};
+use tokio::prelude::*;
+use reqwest::r#async::multipart::Part;
+
+struct FileDecoder;
+
+impl tokio::codec::Decoder for FileDecoder {
+    type Item = Bytes;
+    type Error = std::io::Error;
+
+    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
+        if src.is_empty() {
+            return Ok(None)
+        }
+        Ok(Some(src.take().freeze()))
+    }
+}
+
+pub fn file_to_part(path_to_file: &String) -> Part {
+    let file = tokio::fs::File::open(path_to_file.clone())
+        .map(|file| FramedRead::new(file, FileDecoder))
+        .flatten_stream();
+    let part = Part::stream(file).file_name("file");
+    part
+}