Fields

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What are Fields?

A Field in Flatfile is like a column in a spreadsheet — it defines the data type, format, and any constraints for a single piece of data in your import.

Fields are defined inside a Blueprint, which acts as the master schema for your import setup. The hierarchy works like this:

• A Blueprint defines the structure of one or more Workbooks.
• Each Workbook contains Sheets (like tabs in a spreadsheet).
• Each Sheet contains Fields (columns), which describe the individual data points to be collected.

When you configure a Field, you’re telling Flatfile what kind of data to expect in that column—whether it’s text, a number, a date, or another supported type. You can also apply constraints like “required,” “unique,” or “computed” to control how data is handled during import.

Fields play a key role in ensuring data structure and quality from the moment users start importing.

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Basic Blueprint Structure

• A Blueprint defines the data structure for any number of Spaces
• A Space may contain many Workbooks and many Documents
• A Document contains static documentation and may contain many Document-level Actions
• A Workbook may contain many Sheets and many Workbook-level Actions
• A Sheet may contain many Fields and many Sheet-level Actions
• A Field defines a single column of data, and may contain many Field-level Actions

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Basic Field Configuration

The following examples demonstrate the configuration of isolated fields, which are intended to be used in the context of a Blueprint configuration under a Sheet definition.

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Simple Field Definition

This example configures a single string Field that is required and another a number Field with a decimalPlaces config.

// Basic string field
const nameField = {
  key: "firstName",
  type: "string",
  label: "First Name",
  description: "The customer's first name",
  required: true,
};

// Number field with config
const ageField = {
  key: "age",
  type: "number",
  label: "Age",
  description: "Customer age in years",
  config: {
    decimalPlaces: 2,
  },
};

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Field with Multiple Options

This example configures a single enum field with a status key, Customer Status label, and Current status of the customer description. It also defines four options for the field: active, inactive, pending, and suspended.

const statusField = {
  key: "status",
  type: "enum",
  label: "Customer Status",
  description: "Current status of the customer",
  options: [
    { value: "active", label: "Active" },
    { value: "inactive", label: "Inactive" },
    { value: "pending", label: "Pending" },
    { value: "suspended", label: "Suspended" },
  ],
};

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Field Types

Flatfile supports 9 field types for defining data structure:

Basic Types:

• string - Basic text data
• number - Integer or floating point numbers
• boolean - True/false values
• date - GMT date values in YYYY-MM-DD format

Single Selection:

• enum - Single selection from predefined options

Multiple Value Types:

• string-list - Array of string values
• enum-list - Multiple selections from predefined options

Reference Types:

• reference - Single reference to another sheet
• reference-list - Multiple references to another sheet

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string

A property that should be stored and read as a basic string.

{
  "key": "productCode",
  "label": "Product Code",
  "type": "string",
  "appearance": {
    "size": "m"
  }
}

Note: String fields don’t have type-specific config options, but support appearance settings.

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string-list

Stores an array of string values. Useful for fields that contain multiple text entries.

{
  "key": "tags",
  "label": "Product Tags", 
  "type": "string-list"
}

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number

A property that should be stored and read as either an integer or floating point number.

config.decimalPlaces
The number of decimal places to preserve accuracy to.

{
  "key": "price",
  "label": "Retail Price",
  "type": "number",
  "config": {
    "decimalPlaces": 2
  }
}

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enum

Defines an enumerated list of options for the user to select from (single selection). The maximum number of options for this list is 100. For multiple selections, use enum-list.

config.allowCustom
Permit the user to create new options for this specific field.

config.sortBy
The field to sort the options by (label, value, ordinal).

config.options
An array of valid options the user can select from:

{
  "key": "status",
  "label": "Status",
  "type": "enum",
  "config": {
    "options": [
      {
        "value": "active",
        "label": "Active"
      },
      {
        "value": "inactive",
        "label": "Disabled"
      }
    ]
  }
}

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enum-list

Allows multiple selections from a predefined list of options. Values are stored as an array. Use this instead of enum when users need to select multiple options.

config.allowCustom
Allow users to create new options for this field.

config.sortBy
Sort options by: label, value, or ordinal.

config.options
Array of option objects:

{
  "key": "categories",
  "label": "Product Categories",
  "type": "enum-list", 
  "config": {
    "allowCustom": false,
    "sortBy": "label",
    "options": [
      {
        "value": "electronics",
        "label": "Electronics"
      },
      {
        "value": "clothing",
        "label": "Clothing"
      },
      {
        "value": "books",
        "label": "Books"  
      }
    ]
  }
}

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boolean

A true or false value type. Usually displayed as a checkbox.

config.allowIndeterminate
Allow a neither true or false state to be stored as null.

{
  "key": "is_active",
  "label": "Active",
  "type": "boolean",
  "config": {
    "allowIndeterminate": true
  }
}

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date

Store a field as a GMT date. Data hooks must convert this value into a YYYY-MM-DD format in order for it to be considered a valid value.

{
  "key": "start_date",
  "label": "Start Date",
  "type": "date"
}

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reference

Defines a singular one-to-one reference to a field another sheet.

config.ref
The sheet slug of the referenced field. Must be in the same workbook.

config.key
The key of the property to use as the reference key.

config.filter
Optional filter to narrow the set of records in the reference sheet used as valid values. When provided, only records where the refField value matches the current record’s recordField value will be available as options.

{
  "key": "author",
  "type": "reference",
  "label": "Authors",
  "config": {
    "ref": "authors",
    "key": "name"
  }
}

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Reference Field Filtering

Reference fields can be filtered to show only relevant options based on the value of another field in the same record. This enables cascading dropdowns and dependent field relationships.

Filter Configuration

The filter property accepts a ReferenceFilter object with two required properties:

How Filtering Works

When a filter is applied:

1. The system looks at the value in the recordField of the current record
2. It then filters the referenced sheet to only show records where refField matches that value
3. Only the filtered records become available as options in the reference field

Example: Country and State Cascading Dropdown

Consider a scenario where you want state options to be filtered based on the selected country.

{
  "sheets": [
    {
      "name": "Reference Data",
      "slug": "ref-data",
      "treatments": ["ENUM_REFERENCE"],
      "fields": [
        {
          "key": "country-name",
          "label": "Country",
          "type": "string"
        },
        {
          "key": "state-name",
          "label": "State/Province",
          "type": "string"
        }
      ]
    },
    {
      "name": "Addresses",
      "slug": "addresses",
      "fields": [
        {
          "key": "country",
          "label": "Country",
          "type": "reference",
          "config": {
            "ref": "ref-data",
            "key": "country-name"
          }
        },
        {
          "key": "state",
          "label": "State/Province", 
          "type": "reference",
          "config": {
            "ref": "ref-data",
            "key": "state-name",
            "filter": {
              "refField": "country-name",
              "recordField": "country"
            }
          }
        }
      ]
    }
  ]
}

Reference Data Sheet:

Behavior

• When USA is selected in the country field, the state dropdown will only show California, New York, and Texas
• When Canada is selected in the country field, the state dropdown will only show Ontario and Quebec

The following diagram illustrates how reference field filtering works:

And this is how it looks in the UI:

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reference-list

Defines multiple references to records in another sheet within the same workbook.

config.ref
The sheet slug of the referenced field. Must be in the same workbook.

config.key
The key of the property to use as the reference key.

config.filter
Optional filter to narrow the set of records in the reference sheet used as valid values.

{
  "key": "authors",
  "type": "reference-list",
  "label": "Book Authors", 
  "config": {
    "ref": "authors",
    "key": "name"
  }
}

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Reference List Filtering

The filter property on reference-list fields works identically to reference field filters, but allows for multiple selections.

{
  "key": "categories",
  "label": "Product Categories",
  "type": "reference-list",
  "config": {
    "ref": "category-data",
    "key": "category-name",
    "filter": {
      "refField": "department",
      "recordField": "product-department"
    }
  }
}

Multi-Level Cascading Example

You can create complex, multi-level cascading dropdowns by chaining filtered reference fields together. This example shows a product taxonomy where department selection filters available categories, and category selection filters available subcategories:

{
  "sheets": [
    {
      "name": "Product Taxonomy",
      "slug": "taxonomy",
      "fields": [
        { "key": "department", "label": "Department", "type": "string" },
        { "key": "category", "label": "Category", "type": "string" },
        { "key": "subcategory", "label": "Subcategory", "type": "string" }
      ]
    },
    {
      "name": "Products",
      "slug": "products",
      "fields": [
        {
          "key": "department",
          "label": "Department",
          "type": "reference",
          "config": { "ref": "taxonomy", "key": "department" }
        },
        {
          "key": "category",
          "label": "Category",
          "type": "reference",
          "config": {
            "ref": "taxonomy",
            "key": "category",
            "filter": { "refField": "department", "recordField": "department" }
          }
        },
        {
          "key": "subcategory",
          "label": "Subcategory",
          "type": "reference-list",
          "config": {
            "ref": "taxonomy",
            "key": "subcategory",
            "filter": { "refField": "category", "recordField": "category" }
          }
        }
      ]
    }
  ]
}

Product Taxonomy Sheet:

Behavior

This creates a three-level cascade: Department → Category → Subcategory, where users can select multiple subcategories from the filtered options.

• When Electronics is selected in the department field, the category dropdown will only show Computers and Audio
• When Computers is selected, the subcategory dropdown will show Laptops, Desktops, and Tablets. Users may then select multiple subcategories from the filtered options
• When Clothing is selected, the category dropdown will only show Men’s and Women’s
• When Men’s is selected, the subcategory dropdown will show Shirts and Pants. Users may then select multiple subcategories from the filtered options

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Field Constraints

Field constraints are system-level validation rules that enforce data integrity and business logic on data in individual fields.

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required

Ensures that a field must have a non-null value. Empty cells are considered null values and will fail this constraint.

{
  "key": "email",
  "type": "string",
  "label": "Email Address",
  "constraints": [{ "type": "required" }]
}

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unique

Ensures that field values appear only once across all records in the sheet. Note that null values can appear multiple times as they don’t count toward uniqueness validation.

{
  "key": "employeeId", 
  "type": "string",
  "label": "Employee ID",
  "constraints": [{ "type": "unique" }]
}

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computed

Marks a field as computed, hiding it from the mapping process. Users will not be able to map imported data to fields with this constraint.

{
  "key": "calculatedField",
  "type": "string", 
  "label": "Calculated Value",
  "constraints": [{ "type": "computed" }]
}

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Field-level access

readonly
On a field level you can restrict a user’s interaction with the data to readonly. This feature is useful if you’re inviting others to view uploaded data, but do not want to allow them to edit that field.

{
  "fields": [
    {
      "key": "salary",
      "type": "number",
      "readonly": true
    }
  ]
}

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Field Options

Configurable properties for a Field that define its structure and behavior:

| alternativeNames | array | | [] | Alternative field names for mapping assistance | | metadata | object | | | Arbitrary object of values to pass through to hooks and egress |