ts-runtime-interface

WARNING: This is still very much a work in progress...

Usage

See example for a quick example of usage. Overall what you need to do is:

• Add a prebuild step that runs ts-runtime-interface -p tsconfig.json ./augmented-definitions.d.ts ./schema.json

  This will use your tsconfig.json file to find relevant typescript files and scans for any interfaces leading with the // @runtime.

  These interfaces will be output in JSONSchema format and a type-definition augumentation file will be generated.

  Make sure both of these outputs are in places that

  • TypeScript can find them
  • You can consume them

• In your code, set up the validator with:

  const validate = validator('./path/to/schema.json');

  The resulting function returned will use the schema file to validate any objects passed into it at runtime. If a validation fails, it will throw an exception. If it passes, the returned value should be associated with the interface you annotated with // @runtime.

• Use the validator:

  const safeAPIResult = validate('InterfaceYouAnnotated', unsafeAPIbody);
  
  // safeAPIResult is guarenteed to have type soundness with your system
  //  given that everything was set up properly and there are no bugs
  //  (there are bugs)

FAQ

Ok now one's never actually asked me any of these but...

Doesn't this already exist?

Probably

Then why did you do it?

Why does anyone do anything?

I already use swagger/openAPI/api-blueprint for validation

Good!

I'm not sure if this will be a good fit then. My first thought is that you could use something that generates a typescript interface from swagger (so sort of the reverse of what this is). I don't know which is honestly better. I made this originally for interactions with libraries/APIs which had no standard sort of validation in place.

Why didn't you use <some typescript thing> as the method of annotating an interface as needing runtime validation

I briefly considered having an empty interface that looked like:

interface Validate<AliasedName extends string = ''> {}

But there were a number of questions that lead to complexity (of usage not implementation) that I didn't have reasonable answers to that wouldn't confuse people:

• Do all ancestors of Validate become candidates for runtime validation?
• How do we deal with aliased interfaces

This is slow

That's not a question, but yes, it does have to process your project with the typescript compiler before you actually compile. There should be a way to focus what files have external interfaces at some point, but it's not there yet.