> ## Documentation Index
> Fetch the complete documentation index at: https://wiki.latch.bio/llms.txt
> Use this file to discover all available pages before exploring further.

# Customizing Your Interface

> Latch dynamically constructs the workflow interface based on the workflow function code and the `LatchMetadata` object.

With these, you can specify

<CardGroup cols={2}>
  <Card title="The contact email, repository, social media links, etc." icon="mailbox" iconType="duotone" />

  <Card title="The ordering and grouping of parameters" icon="object-group" iconType="duotone" />

  <Card title="parameter tooltip descriptions" icon="toolbox" iconType="duotone" />

  <Card title="parameter display names" icon="display-code" iconType="duotone" />
</CardGroup>

## Parameter Display

The UI only displays parameters specified in the `LatchMetadata` object:

```python theme={null}
from latch.types import LatchParameter, LatchAppearanceType, LatchRule

metadata = LatchMetadata(
    parameters: {
        'param_0': LatchParameter(
            display_name="Parameter 0",
            description="This is parameter 0",
            hidden=False,
        ),
        'param_1': LatchParameter(
            display_name="Parameter 1",
            description="This is parameter 1",
            hidden=True, # parameter is collapsed
        )
    }
)
...

@workflow(metadata)
def wf(
    param_0: int, # any supported type works
    param_1: str,
    ...
)
```

Each key in `metadata.parameters` must be the name of one of the parameters of the workflow function. Other keys will be ignored. Parameters without a corresponding key in `metadata.parameters` will not be displayed.

* `{class}` `~latch.types.metadata.LatchParameter` specifies the metadata associated with each workflow parameter.
* `{class}` `~latch.types.metadata.LatchAuthor` describes information about the workflow author.
* `{class}` `~latch.types.metadata.LatchRule` describes the rule that the parameter input must follow.

## Custom Parameter Layout (Flow)

By default, parameters are displayed in a flat list, in the order in which they are declared in the metadata. For more complex workflows it is often better to specify a custom layout, known as a "flow".

The custom layout is defined using the `flow` parameter of the `{class}` `~latch.types.metadata.Metadata` specification, which is a list of flow elements. Some flow elements can have child flows. All flow elements can be arbitrarily nested.

## Flow Elements

* `{class}` `~latch.types.metadata.Params` is the most basic flow element which displays the specified parameter widgets one after another. A parameter can be part of any number of `{class}` `~latch.types.metadata.Params` elements. The default workflow layout is equivalent to `flow=[Params("first_param", "second_param", ...)]`
* `{class}` `~latch.types.metadata.Title` and `{class}` `~latch.types.metadata.Text` are decorative flow elements that display a string of title and body text respectively. These elements have full markdown support. They are most often used to explain a parameter or group parameters without cluttering the UI as much as a `{class}` `~latch.types.metadata.Section`
* `{class}` `~latch.types.metadata.Section` displays a child flow in a card with a given title. This is the basic building block of most UIs
* `{class}` `~latch.types.metadata.Spoiler` displays a child flow in a collapsible card with a given title. The spoiler is collapsed by default. This is often used for hiding away parts of the UI that will not be useful to the majority of users
* `{class}` `~latch.types.metadata.Fork` shows a set of mutually-exclusive alternatives. The alternatives are specified as a list of `{class}` `~latch.types.metadata.ForkBranch`, each of which displays a child flow when active and nothing otherwise. Each branch is identified by a unique key. This key is passed to the workflow is a `str`-typed parameter so the user selection can be used to change runtime behavior

Visit the API docs for an example of how to use each flow element.