Why does Nest say it cannot resolve a dependency?
Try code in the playgroundUnderstand the concept
A dependency-resolution error means Nest cannot find or create a required provider in the current module context. The class may exist in source code but still be invisible to the consumer's module. Troubleshooting should follow the token, registration, export and import path.
Important ideas
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Check that the provider is registered in
providers. -
Export it from its module and import that module where it is needed.
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Check the injection token and circular dependencies.
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Interfaces disappear at runtime, so injecting by an interface usually requires an explicit token such as a symbol or string.
Can you explain it without the notes?
Why does Nest say it cannot resolve a dependency?
Use your own words. Explain an example and one limitation before checking the explanation.
Check your explanation
A dependency-resolution error means Nest cannot find or create a required provider in the current module context. The class may exist in source code but still be invisible to the consumer's module. Troubleshooting should follow the token, registration, export and import path.
Turn this concept into a clear answer.
- Avoid fixing every DI error by making modules global; identify the missing dependency boundary.
Adapted from 03_NESTJS.md · “Why does Nest say it cannot resolve a dependency?”. Examples are study fragments; framework behavior can depend on your version.