Change base path on VS publish - visual-studio

Question

I have a blazorWASM project. While developing, I need index.html to have it's base path set to <base href="/" />, but when I use the built-in publish to file, the output is set to land directly into my PHP project which acts as a host that serves WASM static files, and needs this base path: <base href="/wwwroot/" />.
Is there a way to have them automatically switched so I do not keep forgetting to do so? Alternatively, how do I configure the project so that it will work while I debug it on IIS with the wwwroot base path?

Answer 1

You need to add a build task to your CSPROJ Blazor WASM.
Important note: you need Newtonsoft 13.0.1, System.Text.Json isn't supported.
<UsingTask TaskName="ReplaceBaseHRef" TaskFactory="RoslynCodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.Core.dll">
<ParameterGroup>
<InputFilename ParameterType="System.String" Required="true" />
<AppSettingsfile ParameterType="System.String" Required="true" />
<BaseHRefAttribute ParameterType="System.String" Required="true" />
</ParameterGroup>
<Task>
<Reference Include="$(NugetPackageRoot)\newtonsoft.json\13.0.1\lib\netstandard2.0\Newtonsoft.Json.dll" />
<Using Namespace="System" />
<Using Namespace="System.IO" />
<Using Namespace="System.Text" />
<Using Namespace="System.Text.RegularExpressions" />
<Using Namespace="Newtonsoft.Json" />
<Using Namespace="Newtonsoft.Json.Linq" />
<Code Type="Fragment" Language="C#">
<![CDATA[
var inputFile = File.ReadAllText(InputFilename);
var appsetting = File.ReadAllText(AppSettingsfile);
JObject appsettings = JObject.Parse(appsetting);
var baseHRef = appsettings[BaseHRefAttribute].Value<string>();
if (!string.IsNullOrEmpty(baseHRef)) {
Log.LogMessage( MessageImportance.High, baseHRef );
var outputFile = InputFilename;
var matchExpression = "\\<base\\ href=\\\"(.*)\\\"\\ \\/\\>";
var newBaseHRef = $"<base href=\"{baseHRef}\" />";
File.WriteAllText(
outputFile,
Regex.Replace(inputFile, matchExpression, newBaseHRef)
);
}
]]>
</Code>
</Task>
</UsingTask>
<Target Name="ReplaceBaseHRef" AfterTargets="Publish">
<ReplaceBaseHRef InputFilename="$(PublishDir)wwwroot\index.html" AppSettingsfile="$(PublishDir)wwwroot\appsettings.Production.json" BaseHRefAttribute="BaseHRef" />
</Target>
Now take your appsettings.Production.json and add the configuration setting as:
{
"BaseHRef": "/client/",
...
}
now launch the Publish (in folder, IIS or on Azure).
Your index.html will contain <base href="/client/" />.