Validated Parameters

This library simplifies the process of validating and converting string maps, such as query strings or environment variables, into well-typed data structures. It is particularly useful for quickly setting up a well-typed environment for your application.

Installation

``bash
npm install --save validated-parameters
`

Usage

$3

Here's an example of how to use validated-parameters to validate and convert query string parameters in an Azure Function HTTP trigger:

1. Import the required functions and types:

`typescript
import {
getValidParameters,
stringParameter,
numberParameter,
booleanParameter,
optionally,
} from 'validated-parameters';
`

2. Define the expected parameter map:

`typescript
const parameterMap = {
searchText: stringParameter(),
page: numberParameter(),
pageSize: numberParameter(),
includeArchived: booleanParameter(),
};
`

3. Use getValidParameters in your Azure Function:

`typescript
import { AzureFunction, Context, HttpRequest } from '@azure/functions';

const httpTrigger: AzureFunction = async function (
context: Context,
req: HttpRequest
): Promise {
const { searchText, page, pageSize, includeArchived } = getValidParameters(parameterMap, req.query);

// Your logic for handling the request with validated and converted parameters.
};

export default httpTrigger;
`

$3

validated-parameters can be used to create a well-typed environment for your application. In this example, we will set up a centralized, well-typed environment using environment variables:

1. Create a file named environment.ts:

`typescript
import {
makeEnvironment,
stringParameter,
numberParameter,
booleanParameter,
optionally,
} from 'validated-parameters';

const environmentVariables = {
DB_HOST: stringParameter(),
DB_PORT: numberParameter(),
DB_USER: stringParameter(),
DB_PASSWORD: stringParameter(),
ENABLE_CACHE: booleanParameter(),
CACHE_EXPIRATION: optionally(numberParameter()),
};

export const environment = makeEnvironment(environmentVariables);
`

2. Use the environment object in your application:

`typescript
import { environment } from './environment';

console.log(environment.DB_HOST);
console.log(environment.DB_PORT);
console.log(environment.DB_USER);
console.log(environment.DB_PASSWORD);
console.log(environment.ENABLE_CACHE);
console.log(environment.CACHE_EXPIRATION);
`

The environment object provides well-typed access to environment variables, ensuring that your application always uses the correct data types.

$3

validated-parameters also allows you to customize the validation and conversion process by providing optional configuration. For example:

`typescript
const customParameterMap = {
name: stringParameter({
minLength: 2,
maxLength: 100,
onInvalid: (value) => console.warn(Invalid name: ${value}),
}),
age: numberParameter({
min: 18,
max: 120,
onInvalid: (value) => console.warn(Invalid age: ${value}),
}),
isAlive: booleanParameter({
onFailedToConvert: (value, error) => console.error(Failed to convert isAlive: ${value}, error),
}),
isHappy: optionally(booleanParameter()),
};
``