jx:dataValidation

jx:dataValidation adds Excel data validation rules to cells during template processing. Dropdowns, integer ranges, decimal constraints, date ranges, text length limits — configured right in the template, populated from your data.

Syntax

jx:dataValidation(lastCell="B1" type="list" formula1="choices" allowBlank="true")
jx:dataValidation(lastCell="C1" type="whole" operator="between" formula1="1" formula2="100")
jx:dataValidation(lastCell="D1" type="decimal" operator="greaterThan" formula1="0")

Attributes

Attribute	Required	Description
`lastCell`	Yes	Bottom-right cell of the validation area
`type`	Yes	Validation type: `list`, `whole`, `decimal`, `date`, `textLength`, `custom`
`formula1`	Yes	Primary constraint — for `list`, an expression resolving to a comma-separated string or slice; for numeric types, the min/value
`formula2`	No	Secondary constraint — the max value for `between`/`notBetween` operators
`operator`	No	Comparison: `between`, `notBetween`, `equal`, `notEqual`, `greaterThan`, `lessThan`, `greaterThanOrEqual`, `lessThanOrEqual`
`allowBlank`	No	Allow empty cells (default: `true`)
`showInputMessage`	No	Show tooltip when cell is selected (default: `false`)
`inputTitle`	No	Input message title
`inputMessage`	No	Input message body
`showErrorMessage`	No	Show error popup on invalid input (default: `false`)
`errorTitle`	No	Error popup title
`errorMessage`	No	Error popup message
`errorStyle`	No	Error style: `stop`, `warning`, `information` (default: `stop`)

When to use jx:dataValidation

Use it whenever your generated spreadsheet will be edited by humans after generation. Data validation prevents bad input at the source:

Dropdown lists for status fields, categories, or country codes
Integer constraints on quantity columns
Decimal ranges on price/discount fields
Date ranges on scheduling sheets
Text length limits on comment fields

The most common use case — a dropdown list populated from your data:

Cell B2 comment:
  jx:dataValidation(lastCell="B2" type="list" formula1="statusOptions" showInputMessage="true" inputTitle="Status" inputMessage="Pick a status")

data := map[string]any{
    "statusOptions": "Open,In Progress,Closed,Deferred",
}

When a user clicks cell B2 in the output, they get a dropdown with four choices and a helpful tooltip.

Example: Integer range

Constrain a quantity field to whole numbers between 1 and 1000:

Cell C2 comment:
  jx:dataValidation(lastCell="C2" type="whole" operator="between" formula1="1" formula2="1000" showErrorMessage="true" errorTitle="Invalid quantity" errorMessage="Enter a whole number between 1 and 1000" errorStyle="stop")

No Go code needed — the constraints are literals in the template. If a user types 0 or 1500, Excel blocks it with your custom error message.

Example: Decimal with minimum

Ensure a price field is always positive:

Cell D2 comment:
  jx:dataValidation(lastCell="D2" type="decimal" operator="greaterThan" formula1="0" showErrorMessage="true" errorTitle="Invalid price" errorMessage="Price must be greater than zero")

Inside loops

Combine with jx:each to apply validation to every generated row:

Cell A1 comment:
  jx:area(lastCell="D5")
  jx:each(items="items" var="item" lastCell="D1")

Cell B1 comment:
  jx:dataValidation(lastCell="B1" type="list" formula1="categories")

Every row gets the same dropdown. The validation rule is applied per-row during expansion.

Deferred execution

jx:dataValidation uses deferred execution — the validation rules are collected during template processing and applied in a single batch after all rows are written. This is both faster and ensures correct cell references even when rows shift during expansion.

What’s next?

Add structured Excel tables with auto-filter and banded rows:

jx:table →