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

# Advanced Formatting

## Data Types

### How types are determined

To avoid parsing issues in applications consuming the data, Starsheet will automatically infer the data type of a particular field based on all the values of that column. For example, if an entire column only contains numeric values (or null/empty values) the data will be output as a number, but if it contains a mix of numeric values and strings, all instances of that field will be output of strings.

The exception to this is when a sheet has been set to be output as [key-value pairs](#outputting-a-worksheet-as-key-value-pairs), which causes the type of each item to be evaluated independently.

### Booleans

The following values are acceptable as booleans and will be converted to a boolean `true` or `false` in the output:

* A Ticked or Unticked Checkbox

* The string `Y` or `N`

* The string `1` or `0`

* The string `TRUE` or `FALSE`

* When combined  exclusively with the above "truthy" values, a null/empty value will be interpreted as false

### Arrays

Multiple columns can be combined into an array, by using the same column title suffixed with square brackets (`[]`). For example a sheet with the following structure:

| name    | tags\[]     | tags\[]     | tags\[]     |
| ------- | ----------- | ----------- | ----------- |
| item\_a | category\_a | category\_b | category\_c |
| item\_b | category\_b |             |             |

Would produce this output:

```json theme={null}
{
  "worksheet_name": [
	{
		"name": "item_a",
		"tags": ["category_a", "category_b", "category_c"]
	},
	{
		"name": "item_a",
		"tags": ["category_b"]
	}
  ]
}
```

### Objects

To output fields as objects, add periods to the column title to indicate how they should be nested. For example a sheet with the following structure:

| name    | size.height | size.width |
| ------- | ----------- | ---------- |
| item\_a | 200         | 100        |
| item\_b | 400         | 150        |

Would produce this output:

```json theme={null}
{
  "worksheet_name": [
	{
		"name": "item_a",
		"size": {
			"height": 200,
			"width": 100,
		}
	},
	{
		"name": "item_a",
		"size": {
			"height": 200,
			"width": 100,
		}
	}
  ]
}
```

## Excluding Data from Output

### Hiding Worksheets or Columns

To prevent a worksheet or column from being included in the output, prefix the column name or worksheet name with a `#` symbol.

### Hiding Rows

To hide a row, create a column with the heading `!hide` and set it to a true value. A checked tickbox, `1`, `TRUE` or `Y` are all treated as true.

Alternatively, to hide all rows by default, add a column with the heading `!show`. All rows that don't have a true value in this column will be hidden.

## Modifying JSON Document Format

### Outputting a Worksheet as objects indexed by a key

By default, a worksheet is outputted in JSON as an array of objects.

<Frame caption="Default Output">
  ```json theme={null}
  {
    "worksheet_name": [
  	{
  		"first_column_name": "a",
  		"second_column_name": 1,
  	},
  	{
  		"first_column_name": "b",
  		"second_column_name": 2,
  	}
    ]
  }
  ```
</Frame>

If you would prefer it to be output as an object, indexed by a key add a column with the title `!id`. The value of this field will be used as the key.

<Frame caption="Modified output using !id field">
  ```json theme={null}
  {
    "worksheet_name": {
  	"first_value_from_!id_field": {
  		"first_column_name": "a",
  		"second_column_name": 1,
  	},
  	"second_value_from_!id_field": {
  		"first_column_name": "b",
  		"second_column_name": 2,
  	}
    }
  }
  ```
</Frame>

### Outputting a Worksheet as Key-Value Pairs

If a worksheet only contains two columns with the titles `!key` and `!value` they will be output in the following format.

You may still use non-outputted columns such as a commented column or `!hide` in worksheets using this format.

```json theme={null}
{
  "worksheet_name": {
	"key_1": "value_1",
	"key_2": true,
	"key_3": 100,
  }
}
```