# Accordion

> Stacked collapsible sections, like the panels of a settings screen. A Pyzed component for Python desktop GUIs, with examples and its API.

Source: https://albakore.github.io/pyzed/library/accordion/

:::tip[In plain words]
Several sections stacked up, each one opens or closes when you click its title.
:::

Stacked collapsible sections separated by dividers. Sections are `(key, title, content)` tuples or `ui.AccordionSection` objects (with `icon` and a header `end` widget). You own the open state: `open` is a set of keys, a `{key: bool}` dict or `True`, and `on_toggle` receives the key.

`ui.accordion` · Category: [Lists and menus](https://albakore.github.io/pyzed/library/#lists-and-menus) · [Full reference →](https://albakore.github.io/pyzed/reference/ui/#accordion)

**Code:**

```python
rows = lambda *items: pz.column([ui.field(k, ui.switch(v, on_toggle)) for k, v in items], spacing=8)
pz.container(ui.accordion([
    ("editor", "Editor", rows(("Soft wrap", True), ("Minimap", False))),
    ("files", "Files", rows(("Autosave", True))),
    ("git", "Git", ui.muted("Collapsed sections only show their header.")),
], open={"editor", "files"}, on_toggle=on_toggle,
   icons={"editor": "file-code", "files": "folder", "git": "git-branch"}), width=400)
```

## When to use

- For long settings or property panels where users only need a few sections at a time.
- For a single collapsible block, use a [Disclosure](https://albakore.github.io/pyzed/library/disclosure/).

## Usage

```python
import pyzed as pz
from pyzed import ui

class Settings(pz.App):
    def __init__(self):
        self.open = {"editor"}

    def view(self):
        return ui.accordion(
            [("editor", "Editor", ui.muted("…")), ("files", "Files", ui.muted("…"))],
            open=self.open, on_toggle=lambda key: self.open.symmetric_difference_update({key}),
        )
```

## Variants

:::note[About these captures]
Each capture is recorded by pyzed itself, off-screen at 2x, in One Dark or One Light to match this site's theme, and cropped to the component so it shows at its real size. The pointer hovers, presses or types into it; a component that does not react to the pointer cycles through a few themes. With reduced motion you see the first frame. Open **Code** under a capture to see the snippet that draws it; free names such as `on_save` stand for your own callbacks.
:::

### Open sections

```python
pz.container(ui.accordion([("a", "Editor", ui.muted("…")), ("b", "Files", ui.muted("…")),
                           ("c", "Git", ui.muted("…"))], open=set(), on_toggle=on_toggle), width=320)
```

```python
pz.container(ui.accordion([("a", "Editor", ui.muted("Font, wrapping, minimap.")),
                           ("b", "Files", ui.muted("…"))], open={"a"}, on_toggle=on_toggle), width=320)
```

```python
pz.container(ui.accordion([("a", "Editor", ui.muted("Font, wrapping.")),
                           ("b", "Files", ui.muted("Autosave."))], open=True, on_toggle=on_toggle), width=320)
```

### Content

```python
pz.container(ui.accordion([("e", "Editor", ui.muted("…")), ("g", "Git", ui.muted("…"))], open=set(),
                          icons={"e": "file-code", "g": "git-branch"}, on_toggle=on_toggle), width=320)
```

```python
pz.container(ui.accordion([ui.AccordionSection("p", "Problems", ui.muted("…"), icon="circle-x",
                                              end=ui.count_badge(3, tint="error"))],
                          open=set(), on_toggle=on_toggle), width=320)
```

## Events

Accordion has **1 event of its own**, listed below. Like every widget it also has the **18 common events** (`click`, `double_click`, `right_click`, `mouse_enter`, `drag`, `key_down`, `resize`…), attached with `.on(...)`: see [Events](https://albakore.github.io/pyzed/guides/events/) and [Events of every component](https://albakore.github.io/pyzed/library/events/).

| Event | Handler gets | When |
| --- | --- | --- |
| `on_toggle` | `(key)` | Called with the key of the clicked header. |

**Handler gets** is what Pyzed passes to your callable: `()` means nothing. Any handler can also be a message (a value that is not callable), which goes to `update()`.

### Handling the events

The same events written three ways. **Imperative**: methods of the app change `self`. **Declarative**: the handlers produce messages and one `update()` decides. **Functional**: a pure function draws an immutable state and asks for changes with `set_state(...)`. See [Imperative, declarative and functional](https://albakore.github.io/pyzed/guides/code-styles/).

**Imperative:**

```python
class Settings(pz.App):
    def __init__(self):
        self.open = {"editor"}

    def toggle(self, key):               # on_toggle: the key of the clicked header
        self.open ^= {key}

    def view(self):
        return ui.accordion([("editor", "Editor", ui.muted("Font, tabs, wrapping")),
                             ("files", "Files", ui.muted("Autosave, encoding"))],
                            open=self.open, on_toggle=self.toggle)
```

**Declarative:**

```python
from dataclasses import dataclass

@dataclass
class Toggle:
    key: str

class Settings(pz.App):
    open = frozenset({"editor"})

    def update(self, message):
        match message:
            case Toggle(key):
                self.open = self.open ^ {key}

    def view(self):
        return ui.accordion([("editor", "Editor", ui.muted("…")), ("files", "Files", ui.muted("…"))],
                            open=self.open, on_toggle=Toggle)
```

**Functional:**

```python
from dataclasses import dataclass

@dataclass(frozen=True)
class State:
    open: frozenset = frozenset({"editor"})

def view(state, set_state):
    return ui.accordion([("editor", "Editor", ui.muted("…")), ("files", "Files", ui.muted("…"))],
                        open=state.open, on_toggle=lambda key: set_state(open=state.open ^ {key}))
```

## Properties and API

### `ui.accordion`

```python
accordion(
    sections,
    *,
    open=(),
    on_toggle=None,
    icons=None,
    spacing=8,
    padding=(6, 12, 10, 12),
    theme=None,
)
```

Stacked collapsible sections separated by dividers, like the panels of a settings screen. Each header spans the whole width, so the content lines up with the rest of the panel. You own the open state: change it in `on_toggle`.

| Property | Default | Description |
| --- | --- | --- |
| `sections` | *required* | `ui.AccordionSection(key, title, content, icon=None, end=None)` items (or `(key, title, content)` tuples). |
| `open` | `()` | The set of open ids, a `{id: bool}` dict, or `True` for all. |
| `icons` | `None` | `{id: icon}`: a Lucide icon for each header. |
| `spacing` | `8` | Space around the dividers between sections. |
| `padding` | `(6, 12, 10, 12)` | Padding around the content of an open section. |
| `theme` | `None` | Theme to use instead of the current one (`pyzed.theme.current()`). |

Events: `on_toggle` ([events](#events)).

[Full reference →](https://albakore.github.io/pyzed/reference/ui/#accordion)

### `ui.AccordionSection`

```python
class AccordionSection
```

One section of `ui.accordion`: `key`, `title`, `content` and optional `icon` and header `end` widget.

| Property | Default | Description |
| --- | --- | --- |
| `key` | *required* | Key that identifies the subscription (defaults to the message or the function). |
| `title` | *required* | Title. |
| `content` | *required* | Content: a `Widget`, a string or a number (converted to text). |
| `icon` | `None` | Name of a Lucide icon (`pyzed icons` lists them). |
| `end` | `None` | Widgets at the end (right). |

[Full reference →](https://albakore.github.io/pyzed/reference/ui/#accordionsection)

## Related

- [Disclosure](https://albakore.github.io/pyzed/library/disclosure/): One collapsible section with an arrow.
- [Settings group](https://albakore.github.io/pyzed/library/settings-group/): A titled block of field rows, for settings screens.