Allow upload of part images

- Requires API v6

lib/api.dart

@@ -62,11 +62,10 @@ class InvenTreeFileService extends FileService {
 class InvenTreeAPI {
 
   // Minimum required API version for server
-  static const _minApiVersion = 5;
+  static const _minApiVersion = 6;
 
   // Endpoint for requesting an API token
   static const _URL_GET_TOKEN = "user/token/";
-  static const _URL_GET_VERSION = "";
 
   static const _URL_GET_ROLES = "user/roles/";
 
@@ -518,16 +517,18 @@ class InvenTreeAPI {
    * Upload a file to the given URL
    */
   Future<http.StreamedResponse> uploadFile(String url, File f,
-      {String name = "attachment", Map<String, String> fields}) async {
+      {String name = "attachment", String method="POST", Map<String, String> fields}) async {
     var _url = makeApiUrl(url);
 
-    var request = http.MultipartRequest('POST', Uri.parse(_url));
+    var request = http.MultipartRequest(method, Uri.parse(_url));
 
     request.headers.addAll(defaultHeaders());
 
-    fields.forEach((String key, String value) {
-      request.fields[key] = value;
-    });
+    if (fields != null) {
+      fields.forEach((String key, String value) {
+        request.fields[key] = value;
+      });
+    }
 
     var _file = await http.MultipartFile.fromPath(name, f.path);
 

lib/inventree/part.dart

@@ -301,8 +301,26 @@ class InvenTreePart extends InvenTreeModel {
       return img.isNotEmpty ? img : InvenTreeAPI.staticThumb;
     }
 
-    void uploadImage(File image) async {
-      // TODO
+    Future<bool> uploadImage(File image) async {
+      // Upload file against this part
+      final http.StreamedResponse response = await InvenTreeAPI().uploadFile(
+        url,
+        image,
+        method: 'PATCH',
+        name: 'image',
+      );
+
+      if (response == null) {
+        print("uploadImage returned null at '${url}'");
+        return false;
+      }
+
+      if (response.statusCode != 200) {
+        print("uploadImage returned ${response.statusCode} at '${url}'");
+        return false;
+      }
+
+      return true;
     }
 
     // Return the "starred" status of this part