How are unjust enrichment and unjust detriment prevented, in the context of contracts?

What will be an ideal response?

The doctrine of quasi-contract is intended to prevent unjust enrichment and unjust detriment. It allows a court to award monetary damages to a plaintiff for providing work or services to a defendant even though no actual contract existed between the parties. Recovery is generally based on the reasonable value of the services received by the defendant. It does not apply where there is an enforceable contract between the parties. A quasi-contract is imposed where 1. one person confers a benefit on another, who retains the benefit, and 2. it would be unjust not to require that person to pay for the benefit received.