In this lesson, we are going to see how we can define and how our smart contract handles user inputs.

Here is the changes we have made to instruction.rs in this video:

use borsh::BorshDeserialize;
use solana_program::program_error::ProgramError;

pub enum ReviewInstruction {
    AddReview {
        title: String,
        rating: u8,
        description: String,
    },
    UpdateReview {
        title: String,
        rating: u8,
        description: String,
    },
}

#[derive(BorshDeserialize)]
struct ReviewPayload {
    title: String,
    rating: u8,
    description: String,
}

impl ReviewInstruction {
    pub fn unpack(input: &[u8]) -> Result<Self, ProgramError> {
        let (&variant, rest) = input
            .split_first()
            .ok_or(ProgramError::InvalidInstructionData)?;
        let payload = ReviewPayload::try_from_slice(rest).unwrap();
        Ok(match variant {
            0 => Self::AddReview {
                title: payload.title,
                rating: payload.rating,
                description: payload.description,
            },
            1 => Self::UpdateReview {
                title: payload.title,
                rating: payload.rating,
                description: payload.description,
            },
            _ => return Err(ProgramError::InvalidInstructionData),
        })
    }
}