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This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Framework 6.2.12! |
Type Conversion
Some annotated controller method arguments that represent String-based request input (such as
@RequestParam, @RequestHeader, @PathVariable, @MatrixVariable, and @CookieValue)
can require type conversion if the argument is declared as something other than String.
For such cases, type conversion is automatically applied based on the configured converters.
By default, simple types (int, long, Date, and others) are supported. You can customize
type conversion through a WebDataBinder (see DataBinder) or by registering
Formatters with the FormattingConversionService.
See Spring Field Formatting.
A practical issue in type conversion is the treatment of an empty String source value.
Such a value is treated as missing if it becomes null as a result of type conversion.
This can be the case for Long, UUID, and other target types. If you want to allow null
to be injected, either use the required flag on the argument annotation, or declare the
argument as @Nullable.
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As of 5.3, non-null arguments will be enforced even after type conversion. If your handler
method intends to accept a null value as well, either declare your argument as Alternatively, you may specifically handle, for example, the resulting |
