Parse environment variables
Environment variables and configuration values arrive as strings but application logic needs actual booleans.
Zod · Module
z.stringbool
z.stringbool() parses supported boolean-like strings into plain booleans. It is useful for text-based inputs such as environment variables and can encode booleans back to strings.
- Since
- 4.0
How it works
z.stringbool() creates a schema that interprets supported string values as booleans. It is useful when inputs arrive as text, such as environment variables; parsing produces a plain boolean, while encoding can convert booleans back to their string forms.
Syntax
z.stringbool()Returns
A Zod codec/schema that parses supported string values into booleans and encodes booleans into strings.
Key points
- The API was introduced in Zod 4.0.
- It targets text inputs that represent booleans, especially configuration and environment-variable values.
- The text "true" parses to the boolean true.
- The text "1" is accepted as a truthy representation and parses to true.
- The text "on" is another supported truthy representation.
- The text "enabled" is accepted as a truthy representation.
Common mistakes
- Encoding uses the default string spellings "true" and "false" for boolean values.
- This schema is for string input; it converts recognized text into booleans rather than accepting arbitrary values.
Example: Parse a string boolean
import { z } from "zod";
const enabled = z.stringbool();
console.log(enabled.parse("yes"));
console.log(enabled.parse("0"));Converts supported string representations into booleans when parsing.
When to use it
Normalize boolean-like text
A boundary receives values such as "true", "1", "yes", or "on" and should normalize them to booleans.
Encode booleans as strings
A codec pipeline needs to turn booleans back into their default string representations for output.
Interview questions
QWhat does z.stringbool() do?
z.stringbool() defines a schema that converts recognized string representations such as "true", "false", "yes", and "no" into booleans. Parsing a valid string returns a plain boolean.
Follow-up: How can the conversion be reversed? Use the codec's encoding operation: true becomes "true" and false becomes "false" by default.
QWhen would you use z.stringbool() instead of z.boolean()?
It is especially useful for text-based inputs such as environment variables, where boolean-like values arrive as strings. The schema parses those values into boolean data for application code.
Follow-up: Why not use z.boolean()? A regular boolean schema expects boolean input, whereas stringbool handles boolean-like text.
QHow does z.stringbool() behave as a codec?
The API supports both decoding and encoding because it is internally implemented as a codec. decode("true") returns true, while encode(true) returns "true" with the default configuration.
Follow-up: What default output should be expected when encoding false? The default encoded value is the string "false".
Related
z.boolean()z.encode()z.decode()codecs