> For the complete documentation index, see [llms.txt](https://docs.eximee.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.eximee.com/documentation/documentation-en/budowanie-aplikacji/interfejs-uzytkownika/formularze/dynamicznosc-formularza/jezyk-wyrazen.md).
# Expression language
**The language of conditional expressions in Eximee** allows defining conditional logic (e.g. field visibility, activity, requiredness) using JavaScript syntax extended with specific methods. Conditions are written as expressions that the platform **Eximee** checks during application runtime. Below is a description of the syntax, available methods and attributes, as well as tools that make creating and testing conditions easier.
## Conditional expressions in Eximee
* **JavaScript in conditions:** All conditions in the application template can be described with JavaScript expressions. This means that in the condition field we can use standard operators (`==`, `!=`, `>`, `<`, `&&`, `||`, `!`) and JavaScript functions. The syntax allows defining, among others, negation (`!condition`), conjunction (`condition1 && condition2`) and condition alternatives (`condition1 || condition2`).
* **Access to component values:** To retrieve current field values, use the function **`getValue("COMPONENT_ID")`**, where *COMPONENT\_ID* is the identifier of a field, session variable, or component in the form. [This is the recommended way to obtain a component's value (other methods may cause performance issues). ](#user-content-fn-1)[^1]For example, calling `getValue("PoleTekst1")` will return the current text entered in the text field with ID = PoleTekst1.
* **Access to other attributes:** Besides the value, components also have other properties that can be referenced. For this, use the function **`getData("COMPONENT_ID", "ATTRIBUTE")`**, which returns the value of the given component attribute. For example `getData("Checkbox1", "visible")` will return information about the visibility of the field **Checkbox1** (similarly to using `isVisible("Checkbox1")`). The list of available attributes for individual component types is shown in the component documentation and partly discussed in the next section.
* **Data types in conditions:** All values retrieved from fields are treated as text (string) when evaluating the condition. Therefore, for numeric or logical comparisons, you need to convert data types yourself. You can use standard JavaScript functions such as `parseInt()` (conversion to an integer) or `parseFloat()` (conversion to a floating-point number). For boolean values, remember that the string `"true"`/`"false"` should be compared as a string or converted to a boolean type.
* **Constants:** Expressions can use text constants (enclosed in quotes), numeric constants (written directly), and boolean constants (`true`/`false` without quotes).
* **Session variables in conditions:** If you want to use a session variable (global for the application) in a condition, you can reference it via `getValue("NAZWA_ZMIENNEJ")`. In some cases (e.g. inside composite components) you need to prefix the variable name with `@`. For example, the expression `getValue("@zmienna1")=="Y"` will check whether the session variable `zmienna1` has the value "Y". Note: predefined system variables (if any) may not require this prefix. However, it is recommended to use `@` before custom variable names in complex contexts to avoid ambiguity.
* **Complex conditions and dependencies:** You can build complex expressions by combining several comparisons with logical operators. For example, the expression `getValue("Pole1") != "" && parseInt(getValue("Pole2")) > 100.` The expression will return `true` only if *Pole1* is not empty **and at the same time** the numeric value *of Pole2* is greater than 100. When defining conditions that depend on the values of other fields, **remember to define listening** — more on this later (the [**ListeningOn**](#user-content-fn-2)[^2]).
## Component attributes
Each form component has a set of standard attributes describing its state. The most important common attributes are:
* **`value`** – current *internal* component value (e.g. text entered in the field, checkbox selection, selected list option).
* **`displayValue`** – the value *displayed* to the user. It often matches `value`, but for some fields it may differ (e.g. in a Combobox `value` is the code/ID of the selected option, and `displayValue` is the label text).
* **`visible`** – information about the component's visibility (`"true"` or `"false"`). In conditions, you can also use the function `isVisible("ID")` which serves a similar role.
* **`enabled`** – information about the component's activity (editability), takes the value `"true"` when the field is active or `"false"` when it is disabled (non-editable). This attribute determines whether the user can interact with a given field.
Other attributes may be specific to the component type. For example, the drop-down list component (Combobox) provides attributes **`label`** (selected option text), **`description`** (additional description) or **`size`** (number of available options). The component *Statements* has a collection of items `statementsItemControl` representing individual statements. A detailed list of attributes is available in the documentation for each component type.
| | |
| ------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------- |
| Text field |
value displayValue visible
|
| Text area |
value displayValue visible
|
| Date |
value displayValue visible
|
| Date range |
value displayValue visible
|
| Plus/minus |
value displayValue visible
|
| Formatted content (and collapsible) |
value displayValue visible
|
| Value selection from list (Combobox) |
label - text of the selected value description - description of the selected value size - length of the value list
|
| Account selection |
value displayValue visible
|
| Checkbox |
moreInfoButtonClicked value displayValue visible
|
| Radio |
value displayValue visible
|
| Radio group |
value displayValue visible
|
| Tile group |
content - returns displayValue value displayValue visible
|
| Tile | visible |
| Statements |
statementsItemControl value displayValue visible
|
| Slider |
sliderValue value - (defaultValue) displayValue visible
|
| Step Slider |
sliderValue - value value - (defaultValue) displayValue visible
totalFilesSize fileNames externalIds value displayValue visible
|
| Data confirmation component |
wasEdited value displayValue visible
|
| QR code scanner |
value displayValue visible
|
| Map |
value displayValue visible
|
| Specialized component |
value displayValue visible
|
| Frontend component |
value displayValue visible
|
**Referencing attributes in conditions:** As mentioned, the attribute is read using `getData(id, "attribute")`. However, in practice most conditions simply check the field value (`value`) or its visibility/activity. For convenience, Eximee provides dedicated API methods:
* **`getValue("ID")`** – returns the `value` component with the specified ID (most commonly used).
* **`isVisible("ID")`** – returns information about the component's visibility (string `"true"`/`"false"`).
*(Some special components have additional methods, e.g. for handling statement groups – described later.)*
> *Example:* If the text field *EmailAddress* has the identifier `GesTextField5`, then:
>
> * `getValue("GesTextField5")` will return the entered email address,
> * `isVisible("GesTextField5")` will return `"true"` if the field is visible or `"false"` if it has been hidden.
**Special attributes – Statements component:** For components of type *Statements* (list of consents/approvals) there are functions that allow checking whether a specific statement has been selected. The method **`getStatementValue("COMPONENT_ID", "STATEMENT_MID")`** returns the value of the given statement (consent) on this component. In newer versions this function may be available under the name `getStatementItem`. Usage is as follows: e.g. `getStatementValue("Zgody1", "newsletter") == "true"` will return `true`, if in the component with ID *Zgody1,* the statement with identifier (MID) *newsletter* has been accepted by the user.
## Advanced condition editor
Eximee Designer provides **an advanced conditions editor**, which makes creating, editing, and validating conditional expressions easier. This editor includes the following features:
* **Syntax highlighting:** the syntax of JavaScript expressions is color-highlighted, which increases the readability of complex conditions.
* **Auto-complete:** while editing a condition, hints for available variables and form fields are displayed, as well as hints for Eximee API elements and commonly used JS methods.
* **Support for the prefix "`js:"`:** there is no need to manually type the prefix before the condition `"js:"` — the editor omits it in the view and automatically adds it in the source code when the condition is saved. As a result, the user enters only the actual expression, and the platform takes care of the correct format.
**Where the conditions editor is used:** The advanced editor is used in component property fields such as: **visibility condition**, **activity condition (editing)** and **requiredness condition**. These three properties of each form component use the described editor and allow entering a formula that determines whether the component is visible, active (unlocked), and whether it is required to be filled in.
**Syntax hints in the editor:** In condition edit mode, you can use hints by pressing the keys **Ctrl + Space**. This will display a list of available elements to use. Among the hints are:
* *Standard JavaScript functions and properties:* `parseInt()`, `parseFloat()`, the property `.length` (text length) or `size` (list size), as well as other commonly used constructs (e.g. the keyword `empty` for checking empty values).
* *Eximee API:* functions provided by the platform, such as `getValue()`, `getData()`, `isVisible()` or `getStatementValue()`, will appear in the hints list, reminding you of their availability.
* *Field and variable identifiers:* the editor automatically suggests **component MIDs** available in a given form (along with their technical ID in parentheses) and the names of session variables used in the application. This lets you quickly insert a reference to a specific field without having to remember its exact identifier.
> **Tip:** If there are many fields, to quickly find the hint for a specific component in the list, start typing its name (MID) — the list will be filtered. Hints help avoid typos in IDs and let you learn about available functions.
## Examples of using conditional expressions
Below are a few example conditional expressions along with descriptions of what they do. Each example shows a snippet of code used in the condition definition and an explanation:
* ```js
parseInt(getValue("GesTextField3")) > 5
```
– integer comparison: checks whether the numeric value entered in text field `GesTextField3` is greater than 5.
* ```js
parseFloat(getValue("GesTextField5")) < 200.001
```
– floating-point comparison: checks whether the value from text field `GesTextField5` (e.g. amount or number with decimals) is less than 200.001.
* ```js
getValue("GesCheckbox1") == "true"
```
– logical comparison (equality): checks whether the field of type *Checkbox* with ID `GesCheckbox1` is selected (has value `"true"`).
* ```js
getValue("GesCheckbox1") != "true"
```
– logical comparison (inequality): checks whether the same checkbox **no** is selected (i.e. has a value different from `"true"` – in practice `"false"` or has no value).
* ```js
getValue("GesRadioGroup1") == "audi"
```
– text comparison: checks whether in the Radio button group with ID `GesRadioGroup1` the option with value `"audi"` has been selected (e.g. one of the car brands).
* ```js
!!getValue("nazwiskoZew")
```
– double negation: checks whether a given value is not empty. Two exclamation marks convert the value to a boolean type – the expression will return `true`, if the variable or field `nazwiskoZew` has a non-empty value (e.g. the user entered a surname), and `false` otherwise.
* ```js
!getValue("nazwiskoZew")
```
– negation: checks whether the value is empty. It will return `true`, if the field/variable `nazwiskoZew` **has no value** (e.g. the user entered nothing), which in JavaScript is equivalent to the value *falsy* (e.g. empty string `""`).
* ```js
getStatementItem("GesStatementPopup1", "oswiadczenie1") == "true"
```
– condition for component type *Statements*: checks whether in the component with ID `GesStatementPopup1` the statement with identifier (MID) `oswiadczenie1` has been selected by the user (i.e. whether the user accepted this statement).
* ```js
getStatementItem("@GesStatementFlat5", "zdrowotne") == "false"
```
– similar condition for *Statements* inside a composite component: checks whether the statement `zdrowotne` in the component with ID `GesStatementFlat5` (embedded in a composite component, hence the prefix `@`) **has not** been selected by the user.
* ```js
!!!(getValue("@GesTextField13") || getValue("@GesTextField8"))
```
– example of a requiredness condition: triple negation before the expression in parentheses checks whether *both* text fields `GesTextField13` and `GesTextField8` are empty. Inside the parentheses, the `||` operator returns the first non-empty value (or empty, if both values are empty). Applying `!` reverses the result, and `!!` converts it to a boolean. The overall effect is that `true` only if **both fields are empty** (then, for example, another field becomes required). When either field has a value, the expression will return `false` (meaning the requiredness condition is not met, so e.g. the given field does not have to be required).
* ```js
getValue("@GesCombobox1") != 2 && getValue("@GesCombobox1") > 0
```
– a complex condition for a combobox: checks two things at once — whether the value selected in the Combobox field `GesCombobox1` **is not equal to 2** and whether it is **greater than 0**. Such a condition could be used, for example, to verify a choice other than the default one (assuming that the value `0` means no selection, and `2` is some excluded option).
* ```js
isVisible("@GesTextField1") == "true"
```
– visibility state check: the condition will return `true`, if the component with ID `GesTextField1` is currently visible (e.g. another condition has not hidden it). This can be used to make an action depend on whether another field is on the screen.
* ```js
getValue("GesTextField5").length == 10
```
– text length check: the condition returns `true`, if exactly 10 characters were entered in text field `GesTextField5` This can be used, for example, for format validation (checking whether a number has the required length).
*(In the examples above, sample identifiers generated by the system were used, such as **GesTextField5**. In a real project, it is recommended to give fields readable business identifiers (MIDs), which makes it easier to refer to them later in conditions)*
### Conditional expressions in composite and business components
* Inside a composite/business component, to unambiguously indicate a variable/field from that component, prefix the name with `@`:
* `getValue("@variableName")`
* Example: `getValue("@defaultCurrency") == "USD"`.
* Why? During condition evaluation `@` it expands to the component identifier, e.g. `getValue("@variableName")` → `getValue("GesComplexComponent1.variableName")`, which eliminates name collisions with the main form on which the component is placed.
* If there is a name collision (the same variable/field in the main application and in the component) or you want to be precise — use `@` even if the condition works without it.
* Good practice: in composite/business components always prefix variable/field names with `@` in conditional expressions, unless you intentionally want to reference a variable/field from the main form — then omit `@`
* Note: system predefined variables are placed on the main form, so we refer to them directly by name, omitting the sign `@`.
Examples:
* Main form: `getValue("walutaDomyślna") == "USD"`.
* Inside the component (specifically to the variable from this component): `getValue("@defaultCurrency") == "USD"`.
## FAQ – Frequently Asked Questions
**How do I set a component to display conditionally (e.g. after selecting a checkbox)?**\
You need to use the property **Visibility condition (visibleCondition)** available in the component properties panel. In the condition field, enter an expression that should return `true` when the component is to be visible. For example: if the field *AdditionalSection* is to be shown after selecting checkbox *ShowSections (id=GesCheckbox7)*, then set the visibility condition: `getValue("GesCheckbox7") == "true"`. When the user checks the given checkbox, the condition will be met and *AdditionalSection* will become visible.
**The condition does not refresh after another field changes — what am I doing wrong?**\
You are probably missing the setting **listening**. For the component to react to changes in another field value used in the expression, you need to set its **ListeningOn** (Listening) attribute to point to that field. In other words, the component with the condition must "listen to" the component on which the condition depends. In Eximee Designer, you do this in the **Interactions** component properties section — add the dependent field's identifier to the Listening list. Once listening is set correctly, changing one field's value will automatically re-evaluate the condition in the other field.
**How do I check in a condition whether a field is empty or filled?**\
This can be done in several ways. The simplest is to use the fact that an empty string in JavaScript is a *falsy* (falsy). For example: the expression `!getValue("PoleX")` will return `true`, when *PoleX* is empty (negating an empty string gives true). Conversely, the expression `!!getValue("PoleX")` will return `true`, only if *PoleX* has some value (double negation converts the value to boolean while preserving its "truthiness"). Alternatively, you can compare directly to the empty string: `getValue("PoleX") == ""` (empty) or `getValue("PoleX") != ""` (filled).
**Do I need to add the prefix `js:`?**\
No. In the Eximee Designer editor, we enter only the condition expression itself, without any prefixes. The prefix `"js:"` is added automatically in the source code and is used internally to indicate that the condition should be interpreted as a JavaScript script. If you inspect the application's XML configuration, you will see `condition="js:...your_expression..."`, but in the Designer interface you do not need to (and should not) type it yourself.
**How do I define a condition that is always met (always true)?**\
If we want a given action/condition to be *always* true (e.g. so that an element is always visible or an action is always performed), we can enter a true constant as the expression. In practice, it is enough to enter the value **`true`**. The editor will add the appropriate prefix and the condition will be treated as always satisfied. Alternatively, you can enter **`js:true`** in the raw configuration – the effect will be the same. Similarly, an always-false condition can be obtained by entering `false` (which will cause, for example, that a given component will never be visible on its own).
**Can I use any JavaScript functions in conditions?**\
Basic JavaScript functions and operators are supported, especially those suggested by the editor (such as `parseInt`, `parseFloat`, logical operators, etc.). However, remember that the condition is executed in the context of the user's browser, so it should not contain calls that may be incomprehensible or unavailable. A good practice is to limit yourself to simple operations and use the API provided by the Eximee platform (e.g. `getValue`, `getData`, etc.) for consistency and performance. Directly referencing DOM elements or global variables is not supported and may cause errors. If you need complex logic, consider placing it in the validator or service code.
[^1]: I probably wouldn't point readers to other methods, especially since they may cause performance issues.
[^2]: a link would be useful here
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