graphql-sync-dataloaders

0.1.1 verified Fri May 01 auth: no python

Use DataLoaders in Python GraphQL servers that run in a synchronous context (e.g., Django). Current version 0.1.1. Infrequent releases.

pip install graphql-sync-dataloaders

Common errors

error ImportError: cannot import name 'SyncDataLoader' from 'graphql_sync_dataloaders' ↓

cause Incorrect import path or outdated version; SyncDataLoader is available from version 0.1.0 onwards.

fix

Upgrade to latest version: pip install --upgrade graphql-sync-dataloaders. Then import: from graphql_sync_dataloaders import SyncDataLoader

error TypeError: batch_load_fn() missing 1 required positional argument: 'keys' ↓

cause The batch_load_fn method signature expects exactly one argument (keys), but the class may not be properly subclassed or the method is defined incorrectly.

fix

Define batch_load_fn(self, keys) as a method of your subclass. Example: class MyLoader(SyncDataLoader): def batch_load_fn(self, keys): return [...]

Warnings

gotcha SyncDataLoader.batch_load_fn must return a list of values in the exact same order as the input keys. Returning a dict and mapping may produce incorrect order. ↓

fix Always ensure batch_load_fn returns a list parallel to keys, using list comprehension or similar.

deprecated The package has no known deprecations, but it is a very small library with low activity. Check for updates before relying on it for critical production systems. ↓

fix Monitor the GitHub repository for new releases or consider contributing fixes.

Imports

SyncDataLoader

wrong

from graphql_sync_dataloaders.decorators import SyncDataLoader

correct

from graphql_sync_dataloaders import SyncDataLoader

SyncDataLoader is directly exposed from the top-level package, not a submodule.

Quickstart

Example using SyncDataLoader with Django ORM. batch_load_fn must return a list of results parallel to keys.

from graphql_sync_dataloaders import SyncDataLoader

class UserLoader(SyncDataLoader):
    def batch_load_fn(self, keys):
        # keys is a list of user IDs; return list of users in same order
        users = {user.id: user for user in User.objects.filter(id__in=keys)}
        return [users.get(key) for key in keys]

loader = UserLoader()
user = loader.load(1)  # Synchronous call
users = loader.load_many([1, 2, 3])