angular-docs-cn/aio/content/errors/NG0200.md

13 lines
1.0 KiB
Markdown
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

@name Circular Dependency in DI
@category runtime
@videoUrl https://www.youtube.com/embed/CpLOm4o_FzM
@shortDescription Circular dependency in DI detected while instantiating a provider
@description
A cyclic dependency exists when a [dependency of a service](guide/hierarchical-dependency-injection) directly or indirectly depends on the service itself. For example, if `UserService` depends on `EmployeeService`, which also depends on `UserService`. Angular will have to instantiate `EmployeeService` to create `UserService`, which depends on `UserService`, itself.
@debugging
Use the call stack to determine where the cyclical dependency exists. You will be able to see if any child dependencies rely on the original file by [mapping out](guide/dependency-injection-in-action) the component, module, or services dependencies and identify the loop causing the problem.
Break this loop (or circle) of dependency to resolve this error. This most commonly means removing or refactoring the dependencies to not be reliant on one another.