day1.md

Chapter 4

Day 1

1. Explain what lives inside of an account.

• Contract Code
• Account Storage

2. What is the difference between the /storage/, /public/, and /private/ paths?

Storage is the entry point to access data in your account & only owner can access. Anyone can see & access to the Public data Private can access by only owner & owner who gave access to someone.

3. What does .save() do? What does .load() do? What does .borrow() do?

.save() store the data to the account. .load() fetch the stored data from the account. .borrow() borrow reference from the account

4. Explain why we couldn't save something to our account storage inside of a script.

Because Script is only for reading & Execute the output of the contract. If you want to write something in contract then you have to use Transaction.

5. Explain why I couldn't save something to your account.

To save something to your account you have to give access by using prepare(signer: AuthAccount).

6. Define a contract that returns a resource that has at least 1 field in it. Then, write 2 transactions:

pub contract Blockchains {

  pub resource Flow {
    pub var price: UFix64
    init() {
      self.price = 1.447
    }
  }

  pub fun createFlowPrice(): @Flow {
    return <- create Flow()
  }

}

i. A transaction that first saves the resource to account storage, then loads it out of account storage, logs a field inside the resource, and destroys it.

import Blockchains from 0x01
transaction() {
  prepare(signer: AuthAccount) {

    // It will sotred data in account
    let flowPrice <- Blockchains.createFlowPrice()
    signer.save(<- flowPrice, to: /storage/flowPrice)

    // It will loads from the account storage & we will also add panice if there is no data so we can gave error
    let fetchFlowPrice <- signer.load<@Blockchains.Flow>(from: /storage/flowPrice) ?? panic("Lost in account storage")
    log(fetchFlowPrice.price)

    destroy fetchFlowPrice
  }

  execute {

  }
}

ii. A transaction that first saves the resource to account storage, then borrows a reference to it, and logs a field inside the resource.

import Blockchains from 0x01
transaction() {
  prepare(signer: AuthAccount) {

    // It will sotred data in account
    let flowPrice <- Blockchains.createFlowPrice()
    signer.save(<- flowPrice, to: /storage/flowPrice)

    // It will borrow from the resources we are using signer.borrow instead of load
    let borrowFlowPrice = signer.borrow<&Blockchains.Flow>(from: /storage/flowPrice) ?? panic("Lost in account storage no ones there")
    log(borrowFlowPrice.price)
  }

  execute {

  }
}