Make 'post_infraction' catch the right exception

The internal 'api' of our API client has changed: It raises a custom
RespondeCodeError instead of an `aiohttp.ClientError` when an API was
not successful. I updated this utility function to catch the right
exception and added handling for unknown users by notifying the user
of that problem directly.

1 files changed, 17 insertions, 11 deletions

diff --git a/bot/utils/moderation.py b/bot/utils/moderation.py
index 152f9d538..b295e4649 100644
--- a/bot/utils/moderation.py
+++ b/bot/utils/moderation.py
@@ -1,11 +1,11 @@
 import logging
 from datetime import datetime
-from typing import Union
+from typing import Optional, Union
 
-from aiohttp import ClientError
 from discord import Member, Object, User
 from discord.ext.commands import Context
 
+from bot.api import ResponseCodeError
 from bot.constants import Keys
 
 log = logging.getLogger(__name__)
@@ -21,8 +21,8 @@ async def post_infraction(
     expires_at: datetime = None,
     hidden: bool = False,
     active: bool = True,
-):
-
+) -> Optional[dict]:
+    """Posts an infraction to the API."""
     payload = {
         "actor": ctx.message.author.id,
         "hidden": hidden,
@@ -35,13 +35,19 @@ async def post_infraction(
         payload['expires_at'] = expires_at.isoformat()
 
     try:
-        response = await ctx.bot.api_client.post(
-            'bot/infractions', json=payload
-        )
-    except ClientError:
-        log.exception("There was an error adding an infraction.")
-        await ctx.send(":x: There was an error adding the infraction.")
-        return
+        response = await ctx.bot.api_client.post('bot/infractions', json=payload)
+    except ResponseCodeError as exp:
+        if exp.status == 400 and 'user' in exp.response_data:
+            log.info(
+                f"{ctx.author} tried to add a {type} infraction to `{user.id}`, "
+                "but that user id was not found in the database."
+            )
+            await ctx.send(f":x: Cannot add infraction, the specified user is not known to the database.")
+            return
+        else:
+            log.exception("An unexpected ResponseCodeError occurred while adding an infraction:")
+            await ctx.send(":x: There was an error adding the infraction.")
+            return
 
     return response