Fix Block model to match server: nest header with camelCase keys

The block endpoint returns block id / prev / timestamp nested under a
"header" object with camelCase keys (blockId, dcId, prevId, prevProof,
timestamp) and a proof of just {proof}. The previous flat snake_case
Block fields never matched the response and always deserialized empty.
Add a BlockHeader dataclass, nest it in Block, make proof.scheme
optional, and cover it with a unit test. Verified live against a dev
chain.

prime_sdk/__init__.py

@@ -45,6 +45,7 @@ from .contract import ContractClient
 from .errors import DragonchainAPIError, DragonchainError
 from .models import (
     Block,
+    BlockHeader,
     BlockProof,
     GrpcConnectionInfo,
     ListResponse,
@@ -121,6 +122,7 @@ __all__ = [
     "TransactionTypeClient",
     # models
     "Block",
+    "BlockHeader",
     "BlockProof",
     "GrpcConnectionInfo",
     "ListResponse",

prime_sdk/models.py

@@ -301,26 +301,42 @@ class SmartContract:
 
 @dataclass
 class BlockProof:
-    scheme: str = ""
     proof: str = ""
+    scheme: str = ""  # absent on trust-scheme chains; present on PoW
     nonce: int = 0
 
     @classmethod
     def from_dict(cls, d: Dict[str, Any]) -> "BlockProof":
         return cls(
-            scheme=d.get("scheme", ""),
             proof=d.get("proof", ""),
+            scheme=d.get("scheme", ""),
             nonce=d.get("nonce", 0),
         )
 
 
+@dataclass
+class BlockHeader:
+    block_id: str = ""
+    dc_id: str = ""
+    prev_id: str = ""
+    prev_proof: str = ""
+    timestamp: str = ""
+
+    @classmethod
+    def from_dict(cls, d: Dict[str, Any]) -> "BlockHeader":
+        return cls(
+            block_id=d.get("blockId", ""),
+            dc_id=d.get("dcId", ""),
+            prev_id=d.get("prevId", ""),
+            prev_proof=d.get("prevProof", ""),
+            timestamp=d.get("timestamp", ""),
+        )
+
+
 @dataclass
 class Block:
     version: str = ""
-    id: str = ""
-    timestamp: str = ""
-    prev_id: str = ""
-    prev_proof: str = ""
+    header: BlockHeader = field(default_factory=BlockHeader)
     transactions: List[str] = field(default_factory=list)
     proof: BlockProof = field(default_factory=BlockProof)
 
@@ -328,10 +344,7 @@ class Block:
     def from_dict(cls, d: Dict[str, Any]) -> "Block":
         return cls(
             version=d.get("version", ""),
-            id=d.get("block_id", ""),
-            timestamp=d.get("timestamp", ""),
-            prev_id=d.get("prev_id", ""),
-            prev_proof=d.get("prev_proof", ""),
+            header=BlockHeader.from_dict(d.get("header") or {}),
             transactions=d.get("transactions") or [],
             proof=BlockProof.from_dict(d.get("proof") or {}),
         )