Skip to main content

Using Neo Devpack Dotnet

Designed for developers, Neo Devpack Dotnet is a comprehensive toolkit for creating Neo contracts using .net. It offers convenient contract project templates and a compiler.

When developing and deploying a contract, the typical process is the following:

  • Installing a project template
  • Creating a project using templates
  • Writing a contract
  • Compiling the contract
  • Deploying and testing it

This document covers the usage of project templates and the compiler. For further details on writing and deploying your contract, refer to the subsequent sections.

note

  • Ensure that you install project templates and compilers with matching or the most recent versions when setting them up.

  • If it's been a long while since you last updated your project templates and compiler, make sure to update both when using them again.

Neo.SmartContract.Template#

Neo.SmartContract.Template is a project template used when developing Neo smart contracts. After installing the template, you can create a Neo smart contract project using either the Terminal or Visual Studio.

Install the template#

dotnet new install Neo.SmartContract.Template

List all dotnet templates#

dotnet new list

There are three default templates available after installing Neo.SmartContract.Template:

  • neocontractowner - Standard contract template with Owner, including GetOwner and SetOwner methods)

  • neocontractoracle - A contract template using OracleRequest)

  • neocontractnep17 - NEP-17 Contract Template, including Mint and Burn methods)

note

The neocontract template used before has been renamed to neocontractowner.

Uninstall the template#

dotnet new uninstall Neo.SmartContract.Template

Update the template#

dotnet new update Neo.SmartContract.Template

Create a project using templates with Terminal#

dotnet new neocontractowner

The project name defaults to the name of the current directory, you can also specify the project name with -n, --name <name>, e.g. dotnet new neocontractowner -n MyFirstContract.

Create a project using templates with Visual Studio#

In the Visual Studio interface, create a new project, Neo.SmartContract.Template, as shown in the following screenshots:

Neo.Compiler.CSharp#

Neo.Compiler.CSharp (nccs) is the Neo smart contract compiler that compiles the C# language into NeoVM executable OpCodes.

In the project file of the contract project template, you can find the following code, 

<Target Name="PostBuild" AfterTargets="PostBuildEvent">    <Message Text="Start NeoContract converter, Source File: $(ProjectPath)" Importance="high"></Message>    <Exec Command="nccs $(BaseNameArgument) $(NullableArgument) $(CheckedArgument) $(DebugArgument) &quot;$(ProjectPath)&quot;" /></Target>

which is designed to trigger a secondary compilation with nccs after a successful C# compilation. This secondary compilation compiles it to a nef file and outputs the manifest.json file.

Among them, .nef stands for NEO Executable Format, which mainly contains the contracts's executable code. The specific structure can be found on GitHub.

manifest.json represents the manifest of a smart contract. When a smart contract is deployed, it must explicitly declare the features and permissions it will use.

When running, it will be restricted by its declared list of features and permissions, and cannot exhibit any behavior outside the scope of the list.

Install the compiler#

dotnet tool install --global Neo.Compiler.CSharp

List all dotnet tools#

dotnet tool list

Uninstall the compiler#

dotnet tool uninstall --global Neo.Compiler.CSharp

Update the compiler#

dotnet tool update --global Neo.Compiler.CSharp

Compile the contract file with Terminal#

In the Terminal interface, go to the project path and run the following command to build your contract：

dotnet build

or

nccs

Related contract files are outputted under bin\sc path in the contract project directory.

Compile the contract file with Visual Studio#

In the Visual Studio interface, click Build -> Build Solution (Ctrl + Shift + B).

Versioning tips#

  • After successfully creating the project, open it and check if the version of the NuGet package Neo.SmartContract.Framework matches the version of Neo.Compiler.CSharp. If the compiler is up-to-date but Neo.SmartContract.Framework is not, please manually update it to ensure the proper compilation of the project.

  • If you're working on an older contract project, make sure to compile it using the appropriate compiler version.

  • If you are updating a contract project that is quite old, ensure that you have upgraded both the NuGet package Neo.SmartContract.Framework and the compiler to the latest versions, and also make necessary modifications to the contract code.

  • For the most current way of writing contract code, see this document or GitHub. Among other things, the example contracts in GitHub may contain code for the upcoming version (unreleased) of the template and compiler.

References#

NuGet (Neo.SmartContract.Template)

NuGet (Neo.Compiler.CSharp)

GitHub (Neo-Devpack-Dotnet)

GitHub (example contracts)

Contract template for community maintenance: