Tvalidatorr NPM

tvalidatorr

Typescript JSO(N) input validator against Typescript Types

Motivation

Ability to validate various JSO(N) user/3rd patry inputs against type definitions.

Workings

errors will be thrown in the order of detection
read source files that contain types are cached in order to be reused
if no errors are thrown then the input is valid and conforms with the given type

Rules

optional properties are only validated against the type and not the presence
additional properties that are not defined in the source types are considered a violation of input validity

Installing

npm install --save tvalidatorr

Usage

Access to /src

Given type

export interface User {
    id: number;

    active: boolean

    address: Address;

    phone?: Array<string>;

    tasks: Array<Task>;
}

interface Address {
    street: string;

    county: string;

    flatNumber?: number;
}

interface Task {
    name: string;

    priority: number;

    createdAt?: Date;
}

Types can either be pre-loaded

// initialise by pre-loading types
await Validator.initialise({
    files: ['./lib/types/User.ts'],
    callerBaseDir: __dirname
});

const fakeUserInput = {
    id: 101,
    active: true
};

try {
    Validator.validateByName(fakeUserInput, 'User');
} catch (err) {
    console.error(err.message);
    // Input is missing property *address* for type User
}

const moreCompleteFakeUserInput = {
    id: 101,
    active: true,
    address: {
        street: 'Some Street 101'
    }
}

try {
    Validator.validateByName(moreCompleteFakeUserInput, 'User');
} catch (err) {
    console.error(err.message);
    // Input is missing property *address.county* for type User
}

Or loaded and used on the spot

const userWithInvalidTaskInput = {
    id: 101,
    active: true,
    address: {
        street: 'Some Street 101',
        county: 'County near you'
    },
    tasks: [
        {
            name: 'House Duties',
            priority: 'Should be a number!'
        }
    ]
}

try {
    await Validator.validateAsTypeSource(userWithInvalidTaskInput, {
        files: ['./lib/types/User.ts'],
        callerBaseDir: __dirname,
        typeName: 'User'
    });
} catch (err) {
    console.error(err.message);
    //  Input has a User type mismatch at path: *tasks[0].priority* - number type expected
}

Runtime without access to /src type files

Using tparserr to generate type description file

tparserr can be installed as dev and attached to build

npm install --save-dev tparserr

with e.g. npm script attached to the build

"build:types": "tparserr generate -f=./src/lib/types/User.ts -o=./types.json"

once types are described in said json file, they can be used and validated

await Validator.initialiseByTypeDescription('./types.json'); // relative type paths are resolved against process.cwd()

const fakeUserInput = {
    id: 101,
    active: true
};

try {
    Validator.validateByName(fakeUserInput, 'User');
} catch (err) {
    console.error(err.message);
    // Input is missing property *address* for type User
}

const moreCompleteFakeUserInput = {
    id: 101,
    active: true,
    address: {
        street: 'Some Street 101'
    }
}

try {
    Validator.validateByName(moreCompleteFakeUserInput, 'User');
} catch (err) {
    console.error(err.message);
    // Input is missing property *address.county* for type User
}

const userWithInvalidTaskInput = {
    id: 101,
    active: true,
    address: {
        street: 'Some Street 101',
        county: 'County near you'
    },
    tasks: [
        {
            name: 'House Duties',
            priority: 'Should be a number!'
        }
    ]
}

try {
    Validator.validateByName(userWithInvalidTaskInput, 'User');
} catch (err) {
       console.error(err.message);
       //  Input has a User type mismatch at path: *tasks[0].priority* - number type expected
}