$field static method
Creates a field reference for use in MongoDB aggregation expressions.
This method prefixes a field name with '$' to create a field path expression that can be used in aggregation pipelines to reference document fields.
field The name of the field to reference
Example:
var fieldRef = DQ.$field('name'); // Returns: '$name'
// Usage in aggregation:
var projection = DQ.project({
'upperName': {'\$toUpper': DQ.$field('name')}
});
Implementation
static String $field(String field) {
return "\$$field";
}