# ember/template-simple-unless

💼 This rule is enabled in the 📋 `template-lint-migration` [config](https://github.com/ember-cli/eslint-plugin-ember#-configurations).

🔧 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).

<!-- end auto-generated rule header -->

Require simple conditions in `{{#unless}}` blocks. Complex expressions should use `{{#if}}` with negation instead.

## Rule Details

This rule enforces using simple property paths in `{{#unless}}` blocks rather than complex helper expressions.

## Examples

Examples of **incorrect** code for this rule:

```gjs
<template>
  {{#unless (or (eq a 1) (gt b 2))}}
    Complex condition
  {{/unless}}
</template>
```

```gjs
<template>
  {{#unless (and isAdmin (not isBanned))}}
    Not allowed
  {{/unless}}
</template>
```

Examples of **correct** code for this rule:

```gjs
<template>
  {{#unless isHidden}}
    Visible
  {{/unless}}
</template>
```

```gjs
<template>
  {{#unless (eq value 1)}}
    Not one
  {{/unless}}
</template>
```

```gjs
<template>
  {{#if (not (or a b))}}
    Neither
  {{/if}}
</template>
```

## Options

| Name         | Type       | Default | Description                                                                 |
| ------------ | ---------- | ------- | --------------------------------------------------------------------------- |
| `allowlist`  | `string[]` | `[]`    | Helper names allowed inside `{{unless}}`.                                   |
| `denylist`   | `string[]` | `[]`    | Helper names explicitly denied inside `{{unless}}`.                         |
| `maxHelpers` | `integer`  | `1`     | Maximum number of helpers allowed inside `{{unless}}` (`-1` for unlimited). |

## Related Rules

- [no-negated-condition](template-no-negated-condition.md)

## References

- [Wikipedia/boolean algebra](https://en.wikipedia.org/wiki/Boolean_algebra)