assert

assert is a DCL operation that checks document state without mutating it.

Use it as a guardrail before later operations. If the assertion fails, execution stops.

YOp

- assert:
    path: config/database/host
    exists: true
    type: scalar

Parameters

Parameter	Type	Required	Description
path	string	yes	Path to check.
equals	any	no	Expected value for a deep equality check.
exists	boolean	no	true requires the path to exist. false requires it to be absent.
type	string	no	Expected value type. Allowed values are mapping, sequence, and scalar.

At least one of equals, exists, or type must be provided.

Behavior

• Reads the document without changing it.
• All provided conditions must pass.
• Fails fast with ASSERTION_FAILED if a condition is not met.
• Can check values, existence, types, sequence indexes, and match paths.

Errors

Error	Meaning
ASSERTION_FAILED	A declared condition was not met.
INVALID_OP	No assertion condition was provided.

Example

yops:
  - assert:
      path: config/database/host
      exists: true
      type: scalar

Input:

config:
  database:
    host: localhost

Output:

config:
  database:
    host: localhost