Hyperledger Fabric车辆登记征税系统dApp测试异常问题咨询

Hey there! Let's break down your questions one by one to get things sorted out.

Let's go through each of your test cases to identify what's going right, what's wrong, and why:

• Frontend-led record deletion (generates new block): This is 100% correct. When you delete via chaincode, you're submitting a valid transaction to the blockchain. Even with a single node, Fabric will process this transaction, write it to a new block, and update the world state. Important note: Fabric uses logical deletion here— the original record isn't erased from the ledger history, just marked as deleted in the current state.
• Direct CouchDB deletion (no new block): This is a critical mistake! CouchDB is just Fabric's state database—it's a cache for quick lookups of the latest asset state. Modifying it directly bypasses all blockchain transaction rules, which will cause the node's state to diverge from the authoritative ledger. If the node restarts, it will resync state from the block files and overwrite your manual changes anyway. Never edit the state database directly.
• Duplicate records with same Car-ID: Fabric doesn't enforce business-level uniqueness by default—this logic has to be built into your Golang chaincode. The reason you can create duplicates is that your chaincode doesn't check if the Car-ID already exists before creating a new record. You need to add a check using GetState() for the Car-ID; if it returns a non-null value, reject the create request.
• Can't view previous owner info: This is because your chaincode doesn't implement history query logic. Fabric's ledger stores every transaction history for an asset, but the state database only holds the latest state. To see previous owners, you need to add a chaincode function that calls GetHistoryForKey()—this will return all past versions of the vehicle record, including ownership changes.
• Multiple records with same Car-ID: Same as the duplicate issue—no uniqueness validation in your chaincode. Fabric treats each create transaction as valid unless your code explicitly blocks it.

Let's clarify where your data lives in Hyperledger Fabric:

• Ledger: This is the single source of truth, made up of two parts:
  • Block files: These store every transaction ever executed (creates, updates, deletes) in an immutable, sequential chain. This is the permanent, tamper-proof history of all assets.
  • World State: A snapshot of the latest state of all assets, used for fast queries. It's derived from the block files.
• CouchDB: This is an implementation of the world state (the other option is LevelDB). It stores the latest key-value pairs for your assets and supports rich queries, but it's not the authoritative source. The ledger's block files are the real record—CouchDB just mirrors the latest state to make queries faster.

• Stop modifying CouchDB directly immediately—all state changes must go through chaincode transactions.
• Add Car-ID uniqueness checks in your Golang chaincode: Before creating a vehicle, check if the ID exists with GetState(). If it does, return an error.
• Implement a history query function in your chaincode using GetHistoryForKey() to retrieve past owner information.
• Remember: Fabric's "deletion" is logical, not physical—deleted records are still present in the block history, just marked as inactive in the world state.

内容的提问来源于stack exchange，提问作者ibrahimq21