Customization

Below are some examples of how you can customize the behavior of the library. The default values are shown in the snippets below.

Skipping validation

src/env.ts

import { createEnv } from "@t3-oss/env-core";
 
export const env = createEnv({
  // ...
  // Tell the library to skip validation if condition is true.
  skipValidation:
    !!process.env.SKIP_ENV_VALIDATION &&
    process.env.SKIP_ENV_VALIDATION !== "false" &&
    process.env.SKIP_ENV_VALIDATION !== "0",
});

src/env.ts

import { createEnv } from "@t3-oss/env-core";
 
export const env = createEnv({
  // ...
  // Tell the library to skip validation if condition is true.
  skipValidation:
    !!process.env.SKIP_ENV_VALIDATION &&
    process.env.SKIP_ENV_VALIDATION !== "false" &&
    process.env.SKIP_ENV_VALIDATION !== "0",
});

Overriding the default error handler

src/env.ts

import { createEnv } from "@t3-oss/env-core";
 
export const env = createEnv({
  // ...
  // Called when the schema validation fails.
  onValidationError: (error: ZodError) => {
    console.error(
      "❌ Invalid environment variables:",
      error.flatten().fieldErrors
    );
    throw new Error("Invalid environment variables");
  },
  // Called when server variables are accessed on the client.
  onInvalidAccess: (variable: string) => {
    throw new Error(
      "❌ Attempted to access a server-side environment variable on the client"
    );
  },
});

src/env.ts

import { createEnv } from "@t3-oss/env-core";
 
export const env = createEnv({
  // ...
  // Called when the schema validation fails.
  onValidationError: (error: ZodError) => {
    console.error(
      "❌ Invalid environment variables:",
      error.flatten().fieldErrors
    );
    throw new Error("Invalid environment variables");
  },
  // Called when server variables are accessed on the client.
  onInvalidAccess: (variable: string) => {
    throw new Error(
      "❌ Attempted to access a server-side environment variable on the client"
    );
  },
});

Tell when we're in a server context

src/env.ts

import { createEnv } from "@t3-oss/env-core";
 
export const env = createEnv({
  // ...
  // Tell the library when we're in a server context.
  isServer: typeof window === "undefined",
});

src/env.ts

import { createEnv } from "@t3-oss/env-core";
 
export const env = createEnv({
  // ...
  // Tell the library when we're in a server context.
  isServer: typeof window === "undefined",
});