And groups conditions with the AND operator.

FixedError is a hook returning a fixed error.

HasAddedFields is a condition validating `.AddedField` on fields.

HasClearedFields is a condition validating `.FieldCleared` on fields.

HasFields is a condition validating `.Field` on fields.

HasOp is a condition testing mutation operation.

If executes the given hook under condition.

NewChain creates a new chain of hooks.

Not negates a given condition.

On executes the given hook only for the given operation.

Or groups conditions with the OR operator.

Reject returns a hook that rejects all operations that match op.

Unless skips the given hook only for the given operation.

Chain acts as a list of hooks and is effectively immutable.

The ArticleFunc type is an adapter to allow the use of ordinary function as Article mutator.

The CommentFunc type is an adapter to allow the use of ordinary function as Comment mutator.

Condition is a hook condition function.

The TagFunc type is an adapter to allow the use of ordinary function as Tag mutator.