‘is not null’

The unary postfix operator ‘is not null’ is used to check whether a value is not explicitly set to JSON null in JsonQL expressions. It returns a boolean result (true or false).

Note

This operator checks that a value is not a JSON null value. Note that invalid paths and missing values are also considered “not null”. To check for valid/existing values, use the ‘is not undefined’ operator instead.

Operator Priority: 300

Operator Operands

• Operand 1:

  • Type: any valid JsonQL expression (including invalid path).

  • Description: The value to be checked for non-null status.

Evaluation Rules

The is not null operator follows these evaluation rules:

• JSON null value: Returns false if the operand evaluates to a JSON null value

• Non-null values: Returns true for any non-null value (including numbers, strings, booleans, objects, and arrays)

• Invalid paths: Returns true for invalid paths (they are considered “not null”)

• Missing values from queries: Returns true even when a query returns no results (e.g., First() with no matches)

Important

The is not null operator returns true for:

• All non-null JSON values (numbers, strings, booleans, objects, arrays)

• Invalid or non-existent paths

• Empty query results

• Undefined values

It only returns false when the value is explicitly JSON null. Use the is not undefined operator if you need to verify that a path or query result actually exists.

Examples

{
  "Comment_Operator_is_not_null_1": "(invalid.path is not null) evaluates to true.",
  "Operator_is_not_null_1": "$value(invalid.path is not null)",
  "Operator_is_not_null_2": "$value(NullValue is not null == false)",
  "Operator_is_not_null_3": "$value(Int1 is not null)",
  "Operator_is_not_null_5": "$value(Companies.Select(c => c.Employees).First() is not null)",
  "Operator_is_not_null_6": "$value(Companies.Select(c => c.Employees).First(e => e.Age > 200) is not null)"
}