> ## Documentation Index
> Fetch the complete documentation index at: https://cosmo-docs.wundergraph.com/llms.txt
> Use this file to discover all available pages before exploring further.

# String Literals for Enums

> Accept string literals for enum values as an opt-in deviation from the GraphQL specification.

The GraphQL specification distinguishes between enum literals and string literals in an operation document. An enum argument accepts the enum literal `VALUE1`, but not the string literal `"VALUE1"`. By default, the router rejects a string literal used for an enum type with a validation error:

```
Enum "SomeEnum" cannot represent non-enum value: "VALUE1".
```

The `allow_string_literals_for_enums` option accepts such string literals when the string content matches one of the enum's values. Strings that do not match a value are still rejected:

```
Value "NOPE" does not exist in "SomeEnum" enum.
```

<Warning>
  This is a deviation from the GraphQL specification. Servers built on graphql-js reject string literals for enums. Prefer fixing clients to send enum literals. Use this option to keep existing clients working while they migrate.
</Warning>

## Examples

Given the schema:

```graphql theme={"system"}
enum SomeEnum {
  VALUE1
  VALUE2
}

type Query {
  field(arg: SomeEnum): String
}
```

The following queries behave as listed:

```graphql theme={"system"}
{ field(arg: VALUE1) }    # Valid. Enum literal.
{ field(arg: "VALUE1") }  # Invalid by default. Valid with this option enabled.
{ field(arg: "NOPE") }    # Invalid. "NOPE" is not a value of SomeEnum.
```

Variables are not affected by this option. JSON has no enum type, so a string is the standard representation for an enum variable value and is always accepted when it matches an enum value:

```graphql theme={"system"}
query ($arg: SomeEnum) { field(arg: $arg) }
# variables: {"arg": "VALUE1"} is valid with or without this option
```

## Configuration

<Tabs>
  <Tab title="Environment Variable">
    ```bash theme={"system"}
    ENGINE_ALLOW_STRING_LITERALS_FOR_ENUMS=true
    ```
  </Tab>

  <Tab title="YAML">
    ```yaml config.yaml theme={"system"}
    version: "1"

    engine:
      allow_string_literals_for_enums: true
    ```
  </Tab>
</Tabs>

This option is disabled by default. See the [Router Configuration reference](/router/configuration#router-engine-configuration) for all engine flags.