Handle errors

Every error derives from modsmith.errors.ModsmithError, so one except can catch them all:

import modsmith as ms
from modsmith.errors import ModsmithError

try:
    pack = ms.packs.load("pack.mrpack")
    instance = ms.instances.Instance.open("instances/my-pack")
    instance.sync(pack)
except ModsmithError as error:
    print(f"Install failed: {error}")

Errors from your own mistakes, such as passing the wrong type, are ordinary Python errors.

Which error to catch

Error	Meaning
Cancelled	A CancelToken stopped the call
NetworkError	A request failed. status holds the HTTP status, if there was one
DownloadError	A download failed. failures lists a reason for each file
IntegrityError	A file has the wrong size or hash
UnsupportedError	The version, loader or format is not supported
PackError	A modpack file is invalid
PlatformError	A platform could not provide what was requested
LoaderError	A loader could not be installed
ProcessorError	A Forge or NeoForge install step failed
JavaError	A Java runtime could not be found or installed
LauncherError	The launcher’s files could not be used
InstanceError	An instance could not be read or changed
UnresolvedEntriesError	A pack still has files with no download

ProcessorError is a kind of LoaderError, and UnresolvedEntriesError is a kind of InstanceError.

Report failed downloads

A download keeps going when one file fails, then reports them all together:

from modsmith.errors import DownloadError

try:
    instance.sync(pack)
except DownloadError as error:
    for failure in error.failures:
        print(failure)

Tell a bad key from a bad connection

from modsmith.errors import NetworkError

try:
    ms.platforms.Modrinth("my-tool/1.0").get_project("sodium")
except NetworkError as error:
    if error.status is None:
        print("No connection")
    else:
        print("The server answered", error.status)

Retries

Modsmith already retries connection failures, timeouts, and HTTP 429 and 5xx responses, and waits as long as a server asks, up to one minute. A modsmith.net.Session lets you change this:

session = ms.net.Session("my-tool/1.0", attempts=6, backoff=2.0)
modrinth = ms.platforms.Modrinth(session=session)

Logs

Modsmith writes warnings to the modsmith logger, such as when a download moves to another mirror. It stays silent unless you turn logging on:

import logging

logging.basicConfig(level=logging.INFO)