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Filters

Filters feature lets you create custom decorators that will be used on the methods parameters like @@BodyParams@@ or @@Locals@@.

Example

This example shows you how you can implement a filter and decorator to use these, on a method Controller. In this case, we need to retrieve the body content from an Express.Request.

So to do that, you must create a class and annotate it with the @@Filter@@ decorator and in option, implement the @@IFilter@@ interface:

<<< @/docs/docs/snippets/filters/basic-filter.ts

Then create the decorator. This decorator will be used on a controller method.

<<< @/docs/docs/snippets/filters/filter-decorator.ts

And finally you can use your custom filter on your controller/middleware:

<<< @/docs/docs/snippets/filters/filter-usage.ts

UseFilter Options

@@UseFilter@@ allows you to register your custom decorator with few options as following:

  • paramType (ParamTypes): Parameter type like BODY, QUERY, PARAMS, etc...,
  • required (boolean, optional): Throw an error if the value is undefined,
  • expression (string, optional): An expression to parse,
  • useConverter (boolean): Enable json mapper to deserialize value,
  • useValidation (boolean): Enable validation,
  • useType (boolean): Set explicitly the class/model used by the parameters.