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

# Dropdown Columns

> How to add a dropdown column to your importer through code.

You can add a column to your importer directly through the UI of your Fuse account, or you can do so in code using the documentation below.

The Dropdown column type displays a select box for the user to pick from an array of values.

## addColumn Function

The `addColumn` function accepts an object as an argument.

* `internal_key` (String) - required: The internal key used to access a column's value.
* label (String) - required: The user-facing column label that is shown in the interface.
* `column_type` (String) - required: Should be "enum".
* `required` (String) - required: Whether or not the column is required.
* `values` (Array) - required: An array of values for the dropdown.
* `position` (Optional): The position or order of the column.
* `unique` (Optional): Whether values should be unique.
* `validations` (Optional): An array of built-in data validations. See Built-in [Enum Validations](#built-in-enum-validations).
* `transformations` (Optional): An array of built-in data transformations. See [Built-in Enum Transformations](#built-in-enum-transformations)

### Example Code

<Tabs>
  <Tab title="JavaScript">
    ```javascript theme={null}
      const importer = new FuseImporter();

      importer.getSessionToken = ... // see https://fuse-docs.flatirons.com/getting-started/sessions

      const values = ["Pizza", "Sushi", "Burger"];

      const validations = [
        {
          validation_type: "unique_case_insensitive",
          message: "Must be unique (case insensitive)",
        },
      ];

      const transformations = [
        {
          transformation_type: "autodetect",
        },
      ];

      importer.addColumn({
        internal_key: "food_options",
        label: "Food Options",
        column_type: "enum",
        required: true,
        position: 1,
        unique: true,
        values: values,
        validations: validations,
        transformations: transformations,
      });

      importer.show();
    ```
  </Tab>

  <Tab title="TypeScript">
    ```typescript theme={null}
      const importer = new FuseImporter();

      importer.getSessionToken = ... // see https://fuse-docs.flatirons.com/getting-started/sessions

      const values = ["Pizza", "Sushi", "Burger"];

      // ColumnValidations should be imported from "fuse-importer"
      const validations: ColumnValidations<"enum">[] = [
        {
          validation_type: "unique_case_insensitive",
          message: "Must be unique (case insensitive)",
        },
      ];

      // ColumnTransformations should be imported from "fuse-importer"
      const transformations: ColumnTransformations<"enum">[] = [
        {
          transformation_type: "autodetect",
        },
      ];

      importer.addColumn({
        internal_key: "food_options",
        label: "Food Options",
        column_type: "enum",
        required: true,
        position: 1,
        unique: true,
        values: values,
        validations: validations,
        transformations: transformations,
      });

      importer.show();
    ```
  </Tab>
</Tabs>

## Built-in Enum Validations

The options property of `addColumn` accepts an array of validations. For the Enum validation, you can specify two properties:

* `validation_type:` the name of the validation
* `message:` the message showed to the end user if the validation fails

The validations property accepts an array of objects that contains these possible values: `validation_type`, `message`. As the example below:

```javascript theme={null}
validations: [
  {
    validation_type: "unique_case_sensitive",
    message: "Must be unique (case sensitive)",
  },
];
```

### unique\_case\_sensitive

Specifies that the value must be unique using case-sensitive comparison.

```javascript theme={null}
validations: [
  {
    validation_type: "unique_case_sensitive",
    message: "Must be unique (case sensitive)",
  },
];
```

### unique\_case\_insensitive

Specifies that the value must be unique using case-insensitive comparison.

```javascript theme={null}
validations: [
  {
    validation_type: "unique_case_insensitive",
    message: "Must be unique (case insensitive)",
  },
];
```

## Built-in Enum Transformations

The options property of `addColumn` accepts an array of transformations. For the time transformations, you can specify one property:

* `transformation_type:` the name of the transformation

The transformations property accepts an array of objects that contains these possible values: `transformation_type`. As the example below:

```javascript theme={null}
transformations: [
  {
    transformation_type: "autodetect",
  },
];
```

### autodetect

The autodetect transformation analyzes the values in the column and automatically converts them to a more meaningful representation. For example, it can convert numerical values like 0 and 1 to boolean values like true and false.

```javascript theme={null}
transformations: [
  {
    transformation_type: "autodetect",
  },
];
```