# Default Value

Till the date, if imported spreadsheet contains missing value or any column is not mapped, the response uses `{{key}}` as placeholder. By utilizing Default Value functionality developer has more control over format of response they will receive.

## Setting Default Values

Default value can be applied to columns either at the time of adding column or updating column. Wildcard values like `null`, `undefined` can also be used, which available in the dropdown.

Means developer can choose one of these predefined values or write default value as a string of their choice.

1. **null**: Represents the null value.
2. **undefined**: Represents an undefined value.
3. **Empty String**: Represents an empty string.
4. **Empty Array (\[])**: Represents an empty array.
5. **Boolean true**: Represents the boolean value `true`.
6. **Boolean false**: Represents the boolean value `false`.

While providing custom schema you can mention with `defaultValue` key and put your desired string or appropriate `value` from mentioned table.

| Label             | Value           |
| ----------------- | --------------- |
| null              | `<<null>>`      |
| undefined         | `<<undefined>>` |
| Empty String      | `<<>>`          |
| Empty Array (\[]) | `<<[]>>`        |
| Boolean true      | `<<true>>`      |
| Boolean false     | `<<false>>`     |

## When default value gets applied?

The provided default value is used when imported data gets sent to application as response. The default value will be applied to column when,

1. **Column Not Required and Not Selected During Mapping:**
   * When a column is not marked as required, and the user chooses not to select the column during the mapping phase, the default value will be used in response.
2. **Column Not Required and Contains Empty Value:**
   * When a column is not marked as required, and the column contains an empty value, the default value will be applied to fill the gap.

## Providing default value during [runtime-schema](https://docs.impler.io/features/runtime-schema "mention")

Web portal GUI makes it easy to assign default value to column.  Based on needs you can provide default value while providing schema during runtime too.

### Default Value example with [runtime-schema](https://docs.impler.io/features/runtime-schema "mention")

```javascript
// Custom Schema
const schema = {
  columns: [
    { name: "description", required: false, defaultValue: "<<undefined>>" },
    // Other columns...
  ],
};
```

The Default Value functionality provides flexibility and control to developers when importing data. Whether dealing with optional columns or handling empty values, this feature enhances the overall data import experience.

***

If you have any questions, suggestions, or comments. Feel free to reach out to us over [**Discord**](https://discord.impler.io). We’re constantly improving to deliver the best Data Importer for your product, and we value your input.