DotNet Google Vertex AI Search API

A lightweight C# wrapper for Google Vertex AI Search. The retired Google Custom Search Engine API is not supported.

Authentication

The client accepts exactly these credentials:

• PROJECT_ID: Google Cloud project ID
• APP_ID: Vertex AI Search app/engine ID
• API_KEY: Google Cloud API key with Discovery Engine API access

$env:PROJECT_ID="your-project-id"
$env:APP_ID="your-app-id"
$env:API_KEY="your-api-key"

Usage

using GoogleCSE;

var searcher = new GoogleSearch(
    projectId: "your-project-id",
    appId: "your-app-id",
    apiKey: "YOUR_API_KEY");

var results = searcher.Search("dotnet tutorials");

foreach (var item in results)
{
    Console.WriteLine($"{item.Title}: {item.Url}");
}

To limit a website search to a URL pattern, pass siteSearch as the second argument:

var results = searcher.Search(
    "dotnet tutorials",
    siteSearch: "https://example.com/docs/*");

This sends the Vertex AI Search filter expression siteSearch:"https://example.com/docs/*".

Optional constructor arguments configure the Vertex request: location, pageSize, maxPages, and start.

Test Application

The included console application reads only PROJECT_ID, APP_ID, and API_KEY.

dotnet run --project GoogleCSE/GoogleCSE.TestApp/GoogleCSE.TestApp.csproj

See:

https://docs.cloud.google.com/generative-ai-app-builder/docs/migrate-from-cse#api-key-deploy