Transactions

In order to change data in a contract, you need to send a transaction.

In Cadence, transactions (and scripts) are separate from the contract layer, and are written in different files.

Transactions can import any number of deployed contracts, so you can combine many different actions (across contracts) into 1 transcation.

Transactions always look like:

cadence

		
			transaction() {
   prepare(signer: &Account) {

   }
   execute {

   }
}

Transactions have 2 main stages:

prepare - to access/manipulate data inside the signer’s account (to come later…)
execute - to execute actions

Example Contract & Transaction

cadence

		
			// Contract file: Counter.cdc
// Deployed to 0x01
access(all) contract Counter {
   access(all) var count: Int

   access(all) fun increment() {
      self.count = self.count + 1
   }

   init() {
      self.count = 0
   }
}

cadence

		
			// Transaction file: increment.cdc
import Counter from 0x01

transaction() {

   prepare(signer: &Account) {
      // we don't need to do anything 
      // with the signer's data

      // we will learn more about this later
   }

   execute {
      Counter.increment()
   }
}