Child Loaders Execute Despite Parent Loader Returning a Redirect

[0rjan]

A child loader executes even though its parent loader returns a redirect (new NavigationResult({...})). This leads to unexpected behavior where the child loader runs with undefined data instead of being properly canceled or notified that the parent redirected.

Reproduction Steps

1. Define a parent loader (useParentEntityData) that sometimes returns a redirect.
2. Define a child loader (useChildEntityData) that depends on data from useParentEntityData.
3. Define a third-level loader (useGrandchildEntityData) that depends on useChildEntityData.
4. When useParentEntityData returns a redirect, useChildEntityData still executes and receives undefined.
5. useGrandchildEntityData also executes, unknowingly using undefined from useChildEntityData.
6. There is no indication that useParentEntityData returned a redirect, making it difficult to handle this scenario properly.

Expected Behavior

There are two possible expected behaviors depending on the approach taken:

Alternative 1: Automatic Child Loader Cancellation

• When a parent loader returns a redirect, all dependent child loaders should automatically not execute.
• This ensures that child loaders do not run with undefined values and removes the need for additional error handling.
• However, this could limit flexibility if some child loaders need to execute even when a parent redirects.

Alternative 2: Explicit Redirect Metadata Propagation

• Child loaders should still execute but should be able to detect if a parent loader was canceled or redirected via explicit metadata.
• This metadata should be opt-in and propagated explicitly when defining loaders, allowing developers to control which loaders receive this information.
• This approach gives developers more control but requires them to handle redirects manually in child loaders.

Actual Behavior

• The child loader still executes and receives undefined, even though the parent loader redirected.
• Dependent loaders further down the chain also execute, even though their ancestor loader was redirected.
• There is no mechanism for any of these loaders to detect that a parent redirected.

Possible Fixes

There are two possible solutions to address this issue:

Alternative 1: Automatically Cancel Child Loaders

• When a parent loader returns a redirect, all dependent child loaders should be automatically canceled.
• This would prevent child loaders from executing with undefined values and remove the need for additional error handling.
• However, this approach may limit flexibility if some child loaders need to execute even when a parent redirects.

Alternative 2: Explicit Redirect Metadata Propagation

• Expose metadata in DataLoaderContext to indicate if a parent loader was canceled or redirected.
• Ensure that this metadata is explicitly passed when defining child loaders, so developers can decide whether or not a loader should execute based on the redirect state.
• This approach gives developers more control but requires them to handle redirects manually in each child loader.