Dcs-schemas NPM

common-schemas

npm i @dcl/schemas

Design considerations

The main entrypoint of the library export types only (and the helper functions to prevent lockin)
Every type is also a namespace
Type names are PascalCase
Validators and schemas are camelCase

Generating types, validators and schemas

We will export types that also act as values. We do that using the "namespaces" of typescript. That is, every type is also a JS object, including two properties: schema and validate. It can also be a const, but a namespace sounds better.

// Declare type
export type MyType = {
  value: number;
};

// Declare namespace for the type
export namespace MyType {
  export const schema: Schema<MyType> = {
    type: "object",
    properties: {
      value: { type: number },
    },
    additionalProperties: false,
    required: ["value"],
  };

  export const validate = generateValidator<MyType>(schema);
}

In that sense, MyType can be both used as type const a: MyType and as object MyType.validate(a).

Beware that validate has type ValidateFunction<T> which ajv creates automatically. When writing new validations always try to implement it as an ajv validation, even if custom code is needed. See here.

In particular, don't fall in the trap of doing this:

const validator = generateValidator<MyType>(schema);
export const validate = (mt: MyType) =>
  validator.validate(mt) && otherValidations(mt);

By doing this, all the errors reported by the validator.validate function are lost and never returned to the caller.

Type ownership

Please add types and schemas of your domain into the src/<team> folder, also add your team to the CODEOWNERS repository to make sure nobody accidentally changes it without your team noticing it.

Informing changes

Please notify about changes to the schemas to the teams by adding the whole team (i.e. @decentraland/dapps) as reviewers of the pull requests.

It is recommended that if you are a stakeholder of the interoperable parts of Decentraland, you are subscribed to this repository (wathing it in the button up right).

Making changes

To make sure everybody is aware of changes in types, we have a process of api-extraction using https://api-extractor.com. It creates a report file that should be reviewed upon every change and committed as part of the PR.

To generate the file with your changes run npm run refresh-api.

In the CI, npm run check-api is executed to verify the generated file matches the exported types.