How to configure NSwag.msbuild to work across platform building net.core projects?

Question

I would like to be able to drop nswag.json and swagger.json in my rest clients project and get the cs code generated automatically.

Also if the project is up-to-date don't build it again.

Answer 1

In your csproj file add the following code before the closing tag

<PropertyGroup>
    <GeneratedClientsRoot>./*/</GeneratedClientsRoot>
    <GeneratedClientsWildcard>$(GeneratedClientsRoot)*.cs</GeneratedClientsWildcard>
</PropertyGroup>

<ItemGroup>
    <GeneratedClients Include="$(GeneratedClientsWildCard)" />
    <NSwagFiles Include="$(GeneratedClientsRoot)nswag.json" Condition="'@(GeneratedClients)' != ''" />
    <SwaggerFiles Include="$(GeneratedClientsRoot)swagger.json" Condition="'@(GeneratedClients)' != ''" />
</ItemGroup>

<Target Name="ForceGenerateClients" BeforeTargets="CoreCompile" Condition="'@(GeneratedClients)' == ''">
    <CallTarget Targets="GenerateClients" />
</Target>

<Target Name="AutoGenerateClients" BeforeTargets="CoreCompile" Inputs="@(NSwagFiles);@(SwaggerFiles)" Outputs="@(GeneratedClients)">
    <CallTarget Targets="GenerateClients" />
</Target>

<Target Name="GenerateClients">
    <Message Text="Generating swagger clients" Importance="high" />
    <ItemGroup Condition="'@(NSwagFiles)' == ''">
        <NSwagFiles Include="$(GeneratedClientsRoot)nswag.json" />
    </ItemGroup>
    <Exec Command="$(NSwagExe_Core31) run %(NSwagFiles.RelativeDir)%(NSwagFiles.Filename).json" />
    <ItemGroup>
        <NewClients Include="$(GeneratedClientsWildCard)" Exclude="@(GeneratedClients)" />
    </ItemGroup>
    <Message Text="Generated clients @(NewClients)" Importance="high" />
    <ItemGroup>
        <Compile Include="@(NewClients)" />
    </ItemGroup>
</Target>

The first property GeneratedClientsRoot is the folder pattern where your files will exist. If you create a folder for each nswag.json then the default "./*/" is what you need.

If for example you want all clients in the root of your project simply change GeneratedClientsRoot to "./"

The above code will force generate the clients if there are none created and then will detect if changes to nswag files have happened and regenerate clients accordingly.

--Edit - Added nswag.json config example

This is a partial nswag.json config highlighting important configuration bits.

{
    "runtime": "NetCore31",
    "defaultVariables": null,
    "documentGenerator": {
        "fromDocument": {
            "json": "",
            "url": "swagger.json",
            "output": null
        }
    },
    "codeGenerators": {
        "openApiToCSharpClient": {
            "className": "MyRestServiceClient",
            "namespace": "RestServices.MyRestService",
            "output": "MyRestServiceClient.cs"
        }
    }
}

Output needs to be in the same folder as the nswag. Ideally classname matches filename, and don't forget the namespace.

-- Edit 2 - Prerequisites

In order to use this you need to add nugget package nswag.msbuild to your project.

Change NSwagExe_Core31 to NSwagExe_Core21 or whatever framework version you are using. Also change nswag runtime to the correct runtime.