Substrate 区块链应用开发之存证模块的功能开发

存证是一种在线服务，可用于在某一时间点验证计算机文件的存在性，最早是通过比特币网络带有时间戳的交易实现的。
存证的应用场景有：

• 数字版权
• 司法存证
• 供应链溯源
• 电子发票
• ...

存证的作用是：

• 证明文件在某一时间点确实存在
• 证明文件在某一时间点确实没有被篡改
• 证明文件在某一时间点确实由某个人创建

实操

1. Open a terminal shell on your computer.

2. Clone the node template repository by running the following command:

git clone https://github.com/substrate-developer-hub/substrate-node-template

3. Change to the root of the node template directory by running the following command:

    cd substrate-node-template

4. Create a new branch to contain your work:

    git switch -c my-learning-branch-2024-04-05

5. Compile the node template by running the following command:

    cargo build --release

6. In the same terminal where you compiled your node, you can now start the node in development mode by running the following command:

    ./target/release/node-template --dev --tmp

7. polkadot.js.org/apps 查看
   

8. 交易前查询状态 None
   

9. 交易
   

10. 提交交易
    

11. 交易后查询状态
    

问题

1. 编译报错后使用的命令

    cargo clean
    cargo update
    cargo update -p wasm-bindgen
    cargo update -p librocksdb-sys
    cargo update -p schnorrkel@0.11.4
    cargo update -p anstream@0.6.13  -Z sparse-registry    

2. 编译报错：error[E0220]: associated type BlockNumber not found for T
   

解决： 替换T::BlockNumber为BlockNumberFor<T>

• https://substrate.stackexchange.com/questions/9848/associated-type-blocknumber-not-found-for-t

参考

• https://docs.substrate.io/tutorials/build-a-blockchain/build-local-blockchain/
• https://substrate.stackexchange.com/questions/9848/associated-type-blocknumber-not-found-for-t
• https://polkadot.js.org/apps

更多详情

• https://github.com/qiaopengjun5162/substrate-pallets-poe

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