Variable Operators
Variable operators allow you to access data from the input object in your rules.
Overview
DataLogic-rs provides modern variable operators for accessing and validating data:
- val - (Recommended) Access data from the input object using a path
- exists - (Recommended) Check for the existence of fields in the data
- var - (Legacy) Access data from the input object using a path
- missing - (Legacy) Check for missing fields in the data
- missing_some - (Legacy) Check if a minimum number of fields are present
Note: The legacy operators (var, missing, missing_some) will be removed in future versions. It's recommended to use val and exists instead.
val
The val operator is the modern replacement for var. It allows you to access data from the input object using a path.
Syntax
{ "val": "hello" }or to access a nested path:
{ "val": ["hello", "world"] }or with a default value:
{ "val": ["path", default_value] }Parameters
| Parameter | Description |
|---|---|
| path | A string path or array of path segments to the variable in the data object |
| default_value (optional) | Value to return if variable is not found |
Example: Access Simple Variable
Rule:
Data:
Result:
Example: Access Nested Variable with Array Path
Rule:
Data:
Result:
Example: Access Array Value by Index
Rule:
Data:
Result:
exists
The exists operator checks if a field or path exists in the data object and returns a boolean result.
Syntax
{ "exists": "hello" }or for a nested path:
{ "exists": ["hello", "world"] }Parameters
| Parameter | Description |
|---|---|
| path | A string path or array of path segments to check for existence |
Example: Check If Field Exists
Rule:
Data:
Result:
Example: Check Nested Path Existence
Rule:
Data:
Result:
Example: Null Value Check
Rule:
Data:
Result:
Example: Form Validation Using exists
Rule:
Data:
Result:
var (Legacy)
The var operator is a legacy way to access data from the input object using a path.
It will be removed in future versions. Please use val instead.
Syntax
{ "var": "path.to.variable" }or with a default value:
{ "var": ["path.to.variable", default_value] }Parameters
| Parameter | Description |
|---|---|
| path | Path to the variable in the data object (can be dot notation) |
| default_value (optional) | Value to return if variable is not found |
Example: Access Simple Variable
Rule:
Data:
Result:
Example: Access Nested Variable
Rule:
Data:
Result:
Example: Variable with Default Value
Rule:
Data:
Result:
missing (Legacy)
The missing operator is a legacy way to check for missing fields in the data object.
It will be removed in future versions. Please use exists instead.
Syntax
{ "missing": ["field1", "field2", ...] }Parameters
| Parameter | Description |
|---|---|
| fields | Array of field paths to check |
Example: Check Missing Fields
Rule:
Data:
Result:
Example: Form Validation
Rule:
Data:
Result:
missing_some (Legacy)
The missing_some operator is a legacy way to check if a minimum number of fields are present.
It will be removed in future versions. Please use exists with additional logic instead.
Syntax
{ "missing_some": [min_required, ["field1", "field2", ...]] }Parameters
| Parameter | Description |
|---|---|
| min_required | Minimum number of fields required |
| fields | Array of field paths to check |