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 ChatDBFunc type is an adapter to allow the use of ordinary function as ChatDB mutator.

Condition is a hook condition function.