[Federico Laurianti (Laurianti)]

Purpose

Scenario 04-chromadb cannot reach Chroma: GetOrCreateCollection fails with NotFound, so the semantic search has no collection.

• Products moves from ChromaDB.Client 1.0.1-ci-13369893450 to ChromaDotNet.Client 2.14.0, which uses the v2 API of Chroma 1.x. ChromaDB.Client is deprecated on NuGet in favor of ChromaDotNet.Client. The namespace is still ChromaDB.Client.
• Program.cs: the client takes the Chroma address as it is, with new ChromaClient(uri). No more /api/v1.
• MemoryContext.cs: UpsertAsync and QueryAsync, the method names in 2.x. The empty metadata list is no longer passed: it was never filled, and 2.x wants one entry per id or none.
• AppHost: the Chroma image is pinned to chromadb/chroma:1.5.9, the version tested. The untagged image moved from 0.x to 1.x and broke the sample; with a tag, a new major does not break it again.
• Scenario README: the snippets follow the code.

Where the packages are used:

• CommunityToolkit.VectorData.Chroma, the Chroma provider for Microsoft.Extensions.VectorData in the AI Community Toolkit of the .NET Foundation (Chroma: add the MEVD provider CommunityToolkit/AI#58):
  • recommended by Semantic Kernel
  • recommended by LangChain.Databases (README)
  • listed in the .NET community projects of Microsoft Agent Framework
  • used by Generative AI for Beginners .NET
  • used by LangChain .NET
  • used by LangChain.Databases (integration tests)
• ChromaDotNet.Client, which I maintain:
  • used by CommunityToolkit.VectorData.Chroma
  • used by the Aspire Community Toolkit (Add Chroma hosting and client integrations CommunityToolkit/Aspire#2219)
  • used by BotSharp
  • used by LLM Tornado
  • proposed as a module in Testcontainers for .NET

Fixes #71

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• Get the code

git clone https://github.com/Laurianti/eShopLite.git
cd eShopLite
git checkout fix-04-chromadb-client

• Test the code

cd scenarios/04-chromadb/src
dotnet build eShopLite-ChromaDB.slnx

Then run eShopAppHost as in the scenario README and search from the Store.

What to Check

Verify that the following are valid

• The Products log has no "Error creating chromaDB client" and shows "Memory context initialized: True".
• The semantic search in the Store returns products.

Other Information

Tested with chromadb/chroma:1.5.9 and SQL Server 2025 in Docker, .NET SDK 10.0.402:

• Products alone, without Azure OpenAI. Before: "Error creating chromaDB client" with NotFound. After: the products collection is created and the log shows "Memory context initialized: True".
• MemoryContext with deterministic fake embeddings and a fake chat client: 9 products upserted, 9 records in the collection, and the searches return products. The results are the same as with the old client and /api/v1/ against Chroma 0.5.20.
• Full scenario: eShopAppHost with the containers it starts (Chroma 1.5.9, SQL Server 2022) and Azure OpenAI, keyless, with gpt-5.4-mini for chat and text-embedding-3-small for embeddings. Before: the semantic search in the Store shows "No response" and /api/aisearch returns 500. After: 9 records in the products collection, and from the Store "rain jacket" returns Outdoor Rain Jacket and Outdoor Backpack, "something for camping" returns Camping Lantern and Camping Tent.
• Build: 0 errors, the same 13 warnings as before. dotnet format --verify-no-changes on the changed files passes.

[Copilot]

🟢 Approval recommended

The focused migration is internally consistent and has no identified blocking issues; runtime validation was not independently performed.

No open issues 🎉

What changed in this PR

Restores scenario 04’s Chroma connectivity by migrating Products to a Chroma 1.x-compatible client, addressing #71.

Changes:

• Replaces the legacy client and removes the /api/v1 suffix.
• Updates collection operations and omits unused metadata.
• Pins Chroma to 1.5.9 and aligns README examples.

File	Description
scenarios/​04-chromadb/​src/​Products/​Program.cs	Updates client and collection initialization.
scenarios/​04-chromadb/​src/​Products/​Products.csproj	Uses ChromaDotNet.Client 2.14.0.
scenarios/​04-chromadb/​src/​Products/​Memory/​MemoryContext.cs	Updates upsert and query calls.
scenarios/​04-chromadb/​src/​eShopAppHost/​Program.cs	Pins the Chroma container version.
scenarios/​04-chromadb/​README.md	Aligns setup and API examples.

_{Review effort: Balanced}