FastAPI Error Handling: Practical Guide to HTTP Status Codes and Exception Catching
API error handling is crucial for system robustness and user experience, and FastAPI provides a concise and efficient error handling mechanism. The core of the article includes: ### 1. Necessity of Error Handling It is necessary to clarify the error cause and use standard HTTP status codes (e.g., 404 for resource not found, 400 for parameter errors) to avoid system crashes and ensure service stability. ### 2. HTTP Status Codes and FastAPI Applications FastAPI supports all standard status codes. Route functions can directly specify them via `return` or `raise`. For example: `return {"detail": "Item not found"}` returns 404, or `HTTPException` can be used to explicitly throw errors. ### 3. FastAPI Exception Catching Mechanism It is recommended to actively throw errors using `HTTPException` with specified status codes and messages, such as returning 404 when a user does not exist. FastAPI automatically handles parameter type errors and returns a 422 status code. ### 4. Custom Exceptions and Global Fallback Business logic exceptions (e.g., insufficient balance) can be defined and uniformly handled using `@app.exception_handler` to return standard errors. The global exception handler falls back to uncaught exceptions to prevent server crashes. ### Best Practices Use `HTTPException` for standard errors, custom exceptions for business logic, and leverage automatic parameter
Read MoreJava Exception Handling with try-catch: Catching Errors for a Robust Program
This article introduces the core knowledge of Java exception handling. An exception is an unexpected event during program execution (such as division by zero or null pointer), which will cause the program to crash if unhandled; however, handling exceptions allows the program to run stably. A core tool is the try-catch structure: code that may throw exceptions is placed in the try block, and when an exception occurs, it is caught and processed by the catch block, after which the subsequent code continues to execute. Common exceptions include ArithmeticException (division by zero), NullPointerException (null pointer), and ArrayIndexOutOfBoundsException (array index out of bounds). The methods to handle them are parameter checking or using try-catch. The finally block executes regardless of whether an exception occurs and is used to release resources (such as closing files). Best practices: Catch specific exceptions rather than ignoring them (at least print the stack trace), and reasonably use finally to close resources. Through try-catch, programs can handle errors and become more robust and reliable.
Read More