Tutorials ASP.NET Core with Agentic AI Tutorial
RAG Fundamentals — Complete Guide
RAG Fundamentals — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of ASP.NET Core with Agentic AI Tutorial on Toolliyo Academy.
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ASP.NET Core with Agentic AI Tutorial · Lesson 41 of 100
RAG Fundamentals
AI basics ✓ → Agents
Agents · 2 — Build · ~6 min · Module 5: RAG and Vector Databases
What is this?
RAG (retrieval-augmented generation) fetches relevant documents before the LLM answers. AgentNest CRM copilot retrieves account playbooks; hospital assistant pulls protocol PDFs from vector stores.
Why should you care?
Models hallucinate policy without grounding; RAG ties answers to tenant knowledge bases.
See it live — copy this example
Paste into an ASP.NET Core 8+ / AgentNest project, then run with dotnet run (set your API keys in user-secrets).
// AgentNest.Rag/RagPipeline.cs
public sealed class RagPipeline(IEmbeddingGenerator embedder, IVectorStore store, IChatClient chat)
{
public async Task<string> AskAsync(string tenantId, string question, CancellationToken ct)
{
var vector = await embedder.GenerateEmbeddingAsync(question, cancellationToken: ct);
var hits = await store.SearchAsync(tenantId, vector, topK: 5, ct);
var context = string.Join("\n---\n", hits.Select(h => h.Text));
var prompt = $"Use only this context:\n{context}\n\nQuestion: {question}";
return (await chat.GetResponseAsync([prompt], cancellationToken: ct)).Text;
}
}
What happened?
- RagPipeline embeds the question, searches tenant vectors, injects hits into the prompt, then generates the answer.
- Follow the steps below — typing the code yourself is the fastest way to learn.
Practice next
- build IVectorStore abstraction in AgentNest.Rag.
- Index CRM PDFs per tenant with embedding batch jobs.
- Add RagPipeline to DI and expose POST /api/rag/ask.
- Add reranker step after vector search.
- Return citations array alongside answer text.
Remember
RAG = retrieve relevant chunks, then generate with context. Always filter vector search by tenantId. Log chunk IDs for traceability in AgentNest.
CRM playbook answers
Reps ask how to handle enterprise discount requests.
Outcome: RAG pulls approved playbook sections instead of inventing pricing policy.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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