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Data Expressions

Data Expressions allow you to compute values dynamically inside your templates.

Eledo automatically prepares input fields from your template and inserts values into the generated PDF based on data provided via API. Data Expressions are used in both steps — they define which input fields are created and how the data is processed and displayed.

A Data Expression consists of multiple elements, where the most important one is a variable. When you save your template, Eledo creates input fields from all variables used in the template.

Elements​

A Data Expression can contain:

  • Name — variable
  • 123 — constant number
  • "Peter" — constant string
  • + — operator
  • ABS(X) — function

Variables​

A variable represents a value provided as input.

A variable name:

  • can contain upper and lower case letters
  • can contain underscores
  • cannot start with an underscore

Valid examples:

Name
email
UnitPrice
order_number

Object access​

You can access nested values using dot notation:

Address.City

This expression refers to the City variable inside the Address object.

Numbers​

Numbers are handled with high precision.

Supported format:

123.456
  • must start with digits
  • optional decimal part
  • uses . as the decimal separator

Operators​

You can use the following operators:

+  -  *  /  %  >  >=  <  <=  =  ==  !=

They allow basic calculations and comparisons directly in the template.

Functions​

Functions provide more advanced data processing. They are grouped into categories.

General functions​

IF SWITCH FOR NEXTCOUNTER PROPERTY DEFAULT

Text functions​

CONCAT LENGTH LEFT RIGHT UPPER LOWER CAPITALIZE CAPITALIZEFULLY CHARAT SPLIT REGEX REPLACE NUM CURR ROUND

Date functions​

DATE TO_DATE DAYS DAYS_BETWEEN TODAY

Array functions​

SIZE FILTER SORT_ASC SORT_DESC GET FIRST LAST MAP JOIN

Logical functions​

NOT AND OR

Statistical functions​

SUM SUMC

Types​

A variable can be one of the following types:

  • boolean
  • number
  • string
  • date
  • object
  • array

The default type is string.

Type resolution​

Eledo automatically determines variable types based on how they are used.

Example:

A + 3

In this case, A is treated as a number.

This helps prevent input errors by ensuring the correct data type is used.

Mixed usage​

If a variable is used in different contexts:

A + 3
A + ".pdf"

The variable could be interpreted as either number or string.

If resolved as a string, the first expression could fail. To prevent this, Eledo resolves A as a number.

Manual override​

You can override variable types in the Input Fields section of the Template Editor.

If overridden:

  • the selected type is enforced
  • expressions behave accordingly

Example:

If A is forced to string:

A + 3

This expression will be evaluated as text concatenation instead of numeric addition.

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