Move away from using the body var for Jinja2 templates

docs/example.md

@@ -30,7 +30,7 @@ conf = ConnectionConfig(
     MAIL_FROM = "your@email.com",
     MAIL_PORT = 587,
     MAIL_SERVER = "your mail server",
-    MAIL_FROM_NAME="Desired Name"
+    MAIL_FROM_NAME="Desired Name",
     MAIL_TLS = True,
     MAIL_SSL = False,
     USE_CREDENTIALS = True,
@@ -117,6 +117,10 @@ async def send_file(
 
 ### Using Jinja2 HTML Templates
 
+You can enable Jinja2 HTML Template emails by setting the `TEMPLATE_FOLDER` configuration option, and supplying a 
+value (which is just the name of the template file within the `TEMPLATE_FOLDER` dir) for the `template_name` parameter 
+in `FastMail.send_message()`. You then can pass a Dict as the `template_body` property of your `MessageSchema` object:
+
 ```python
 
 class EmailSchema(BaseModel):
@@ -151,6 +155,37 @@ async def send_with_template(email: EmailSchema) -> JSONResponse:
 
 ```
 
+For example, assume we pass a `template_body` of:
+
+```json
+{
+  "first_name": "Fred",
+  "last_name": "Fredsson"
+}
+```
+
+We can reference the variables in our Jinja templates as per normal:
+
+```
+...
+<span>Hello, {{ first_name }}!</span>
+...
+```
+
+#### Legacy Behaviour (<= 0.4.0)
+
+The original behaviour in <= 0.4.0 was to wrap the Dict you provide in a variable named `body` when it was provided to 
+Jinja behind the scenes. In these versions, you can then access your dict in your template like so:
+
+```
+...
+<span>Hello, {{ body.first_name }}!</span>
+...
+```
+
+As you can see our keys in our dict are no longer the top level, they are part of the `body` variable. Nesting works 
+as per normal below this level also. 
+
 ##  Guide for email utils
 
 The utility allows you to check temporary email addresses, you can block any email or domain. 

fastapi_mail/fastmail.py

@@ -39,12 +39,12 @@ def _record(message):
 
 
 class FastMail(_MailMixin):
-    '''
+    """
     Fastapi mail system sending mails(individual, bulk) attachments(individual, bulk)
 
     :param config: Connection config to be passed
 
-    '''
+    """
 
     def __init__(self,
                  config: ConnectionConfig
@@ -55,14 +55,23 @@ def __init__(self,
     async def get_mail_template(self, env_path, template_name):
         return env_path.get_template(template_name)
 
+    @staticmethod
+    def make_dict(data):
+        try:
+            return dict(data)
+        except ValueError:
+            raise ValueError(f"Unable to build template data dictionary - {type(data)} is an invalid source data type")
+
     async def __prepare_message(self, message: MessageSchema, template=None):
         if template is not None:
             template_body = message.template_body
             if template_body and not message.html:
-                message.template_body = template.render(body=template_body)
+                template_data = self.make_dict(template_body)
+                message.template_body = template.render(**template_data)
                 message.subtype = "html"
             elif message.html:
-                message.html = template.render(body=message.html)
+                template_data = self.make_dict(message.html)
+                message.html = template.render(**template_data)
 
         msg = MailMsg(**message.dict())
         if self.config.MAIL_FROM_NAME is not None: