environmentVariable

Loads, expands, and validates environment variables. This version returns an Either result. If you prefer throwing behavior, use environmentVariableOrThrow.

Example

import { environmentVariable } from "@duplojs/server-utils";
import { DP, E, unwrap } from "@duplojs/utils";

const firstResult = await environmentVariable({
	APPLICATION_NAME: DP.string(),
});
// firstResult: E.Success<{ APPLICATION_NAME: string }> | E.Left<unknown>

if (E.isRight(firstResult)) {
	const parsedVariables = unwrap(firstResult);
	// parsedVariables.APPLICATION_NAME: string
}

const secondResult = await environmentVariable(
	{
		APPLICATION_NAME: DP.string(),
		API_URL: DP.string(),
	},
	{
		paths: [".env", ".env.local"],
		override: true,
		justRead: true,
	},
);
// secondResult: E.Success<{ APPLICATION_NAME: string; API_URL: string }> | E.Left<unknown>

Other examples

Throw variant

import { environmentVariableOrThrow } from "@duplojs/server-utils";
import { DP } from "@duplojs/utils";

const parsedVariables = await environmentVariableOrThrow(
	{
		APPLICATION_NAME: DP.string(),
		APPLICATION_PORT: DP.number(),
	},
	{
		paths: [".env"],
		override: false,
		justRead: true,
	},
);
// parsedVariables: { APPLICATION_NAME: string; APPLICATION_PORT: number }

Syntax

function environmentVariable<
	GenericShape extends DP.DataParserObjectShape
>(
  shape: GenericShape,
  params?: EnvironmentVariableParams
): Promise<
  | E.Success<DP.DataParserObjectShapeOutput<GenericShape>>
  | FileSystemLeft<"read-text-file">
  | E.Error<DP.DataParserError>
>

Parameters

• shape (GenericShape) : schema used to parse and validate environment variables.
• params (EnvironmentVariableParams, optional) : behavior options.
• params.paths (string[], optional) : env file paths to read.
• params.override (boolean, default false) : allows file values to replace existing runtime values.
• params.justRead (boolean, default false) : reads and validates without writing back to runtime environment variables.

Return value

• E.Success<DP.DataParserObjectShapeOutput<GenericShape>> : parsed variables that match the schema.
• FileSystemLeft<"read-text-file"> : if reading an env file fails.
• E.Error<DP.DataParserError> : if schema validation fails.

See also

• setCurrentWorkingDirectory - Changes the current working directory.