blockchain_findAndgetData.go

package main

import (
	"bytes"
	"errors"
	"github.com/boltdb/bolt"
	"log"
)

//查询区块链当中确实存在此笔交易
// FindTransaction finds a transaction by its ID
func (bc *Blockchain) FindTransaction(ID []byte) (Transaction, error) {
	bci := bc.Iterator()

	for {
		block := bci.Next()

		for _, tx := range block.Transactions {
			if bytes.Compare(tx.ID, ID) == 0 {
				return *tx, nil
			}
		}

		if len(block.PrevBlockHash) == 0 {
			break
		}
	}

	return Transaction{}, errors.New("Transaction is not found")
}




// GetBestHeight returns the height of the latest block
func (bc *Blockchain) GetBestHeight() int {
	var lastBlock Block

	err := bc.db.View(func(tx *bolt.Tx) error {
		b := tx.Bucket([]byte(blocksBucket))
		lastHash := b.Get([]byte("l"))
		blockData := b.Get(lastHash)
		lastBlock = *DeserializeBlock(blockData)

		return nil
	})
	if err != nil {
		log.Panic(err)
	}

	return lastBlock.Height
}

// GetBlock finds a block by its hash and returns it
func (bc *Blockchain) GetBlock(blockHash []byte) (Block, error) {
	var block Block

	err := bc.db.View(func(tx *bolt.Tx) error {
		b := tx.Bucket([]byte(blocksBucket))

		blockData := b.Get(blockHash)

		if blockData == nil {
			return errors.New("Block is not found.")
		}

		block = *DeserializeBlock(blockData)

		return nil
	})
	if err != nil {
		return block, err
	}

	return block, nil
}

// GetBlockHashes returns a list of hashes of all the blocks in the chain
func (bc *Blockchain) GetBlockHashes() [][]byte {
	var blocks [][]byte
	bci := bc.Iterator()

	for {
		block := bci.Next()

		blocks = append(blocks, block.Hash)

		if len(block.PrevBlockHash) == 0 {
			break
		}
	}

	return blocks
}