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use pydantic_core.to_json

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This commit is contained in:
Jeremiah Lowin 2025-04-30 17:29:38 -04:00
commit a9253d3111
9 changed files with 24 additions and 49 deletions
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5
src/fastmcp/prompts/prompt.py
View file

@ -3,7 +3,6 @@
from __future__ import annotations as _annotations
import inspect
import json
from collections.abc import Awaitable, Callable, Sequence
from typing import TYPE_CHECKING, Annotated, Any, Literal
@ -192,7 +191,9 @@ class Prompt(BaseModel):
content = TextContent(type="text", text=msg)
messages.append(Message(role="user", content=content))
else:
content = json.dumps(pydantic_core.to_jsonable_python(msg))
content = pydantic_core.to_json(
msg, fallback=str, indent=2
).decode()
messages.append(Message(role="user", content=content))
except Exception:
raise ValueError(

11
src/fastmcp/resources/types.py
View file

@ -97,15 +97,12 @@ class FunctionResource(Resource):
if isinstance(result, Resource):
return await result.read(context=context)
if isinstance(result, bytes):
elif isinstance(result, bytes):
return result
if isinstance(result, str):
elif isinstance(result, str):
return result
try:
return json.dumps(pydantic_core.to_jsonable_python(result))
except (TypeError, pydantic_core.PydanticSerializationError):
# If JSON serialization fails, try str()
return str(result)
else:
return pydantic_core.to_json(result, fallback=str, indent=2).decode()
except Exception as e:
raise ValueError(f"Error reading resource {self.uri}: {e}")

9
src/fastmcp/server/server.py
View file

@ -14,7 +14,6 @@ from typing import TYPE_CHECKING, Any, Generic, Literal
import anyio
import httpx
import pydantic_core
import uvicorn
from mcp.server.lowlevel.helper_types import ReadResourceContents
from mcp.server.lowlevel.server import LifespanResultT
@ -27,6 +26,7 @@ from mcp.types import (
EmbeddedResource,
GetPromptResult,
ImageContent,
PromptMessage,
TextContent,
)
from mcp.types import Prompt as MCPPrompt
@ -435,7 +435,12 @@ class FastMCP(Generic[LifespanResultT]):
messages = await self._prompt_manager.render_prompt(
name, arguments=arguments or {}, context=context
)
return GetPromptResult(messages=pydantic_core.to_jsonable_python(messages))
return GetPromptResult(
messages=[
PromptMessage(role=m.role, content=m.content) for m in messages
]
)
else:
for server in self._mounted_servers.values():
if server.match_prompt(name):

19
src/fastmcp/tools/tool.py
View file

@ -1,7 +1,6 @@
from __future__ import annotations
import inspect
import json
from collections.abc import Callable
from typing import TYPE_CHECKING, Annotated, Any
@ -166,23 +165,7 @@ def _convert_to_content(
return other_content + mcp_types
# if the result is a bytes object, convert it to a text content object
if not isinstance(result, str):
try:
jsonable_result = pydantic_core.to_jsonable_python(result)
if jsonable_result is None:
return [TextContent(type="text", text="null")]
elif isinstance(jsonable_result, bool):
return [
TextContent(
type="text", text="true" if jsonable_result else "false"
)
]
elif isinstance(jsonable_result, str | int | float):
return [TextContent(type="text", text=str(jsonable_result))]
else:
return [TextContent(type="text", text=json.dumps(jsonable_result))]
except Exception:
result = str(result)
result = pydantic_core.to_json(result, fallback=str, indent=2).decode()
return [TextContent(type="text", text=result)]

2
tests/resources/test_function_resources.py
View file

@ -95,7 +95,7 @@ class TestFunctionResource:
fn=lambda: MyModel(name="test"),
)
content = await resource.read()
assert content == '{"name": "test"}'
assert content == '{\n "name": "test"\n}'
async def test_custom_type_conversion(self):
"""Test handling of custom types."""

2
tests/resources/test_resource_template.py
View file

@ -295,7 +295,7 @@ class TestResourceTemplate:
assert isinstance(resource, FunctionResource)
content = await resource.read()
assert content == "hello"
assert content == '"hello"'
async def test_wildcard_param_can_create_resource(self):
"""Test that wildcard parameters are valid."""

2
tests/server/test_mount.py
View file

@ -227,7 +227,7 @@ class TestResourcesAndTemplates:
async with Client(main_app) as client:
resource = await client.read_resource("data+data://users")
assert isinstance(resource[0], TextResourceContents)
assert resource[0].text == '["user1", "user2"]'
assert resource[0].text == '[\n "user1",\n "user2"\n]'
async def test_mount_with_resource_templates(self):
"""Test mounting a server with resource templates."""

10
tests/server/test_server_interactions.py
View file

@ -104,7 +104,7 @@ class TestTools:
async with Client(tool_server) as client:
result = await client.call_tool("list_tool", {})
assert isinstance(result[0], TextContent)
assert result[0].text == '["x", 2]'
assert result[0].text == '[\n "x",\n 2\n]'
class TestToolReturnTypes:
@ -130,7 +130,7 @@ class TestToolReturnTypes:
async with Client(mcp) as client:
result = await client.call_tool("bytes_tool", {})
assert isinstance(result[0], TextContent)
assert result[0].text == "Hello, world!"
assert result[0].text == '"Hello, world!"'
async def test_uuid(self):
mcp = FastMCP()
@ -144,7 +144,7 @@ class TestToolReturnTypes:
async with Client(mcp) as client:
result = await client.call_tool("uuid_tool", {})
assert isinstance(result[0], TextContent)
assert result[0].text == str(test_uuid)
assert result[0].text == f'"{test_uuid}"'
async def test_path(self):
mcp = FastMCP()
@ -158,7 +158,7 @@ class TestToolReturnTypes:
async with Client(mcp) as client:
result = await client.call_tool("path_tool", {})
assert isinstance(result[0], TextContent)
assert result[0].text == str(test_path)
assert result[0].text == f'"{test_path}"'
async def test_datetime(self):
mcp = FastMCP()
@ -172,7 +172,7 @@ class TestToolReturnTypes:
async with Client(mcp) as client:
result = await client.call_tool("datetime_tool", {})
assert isinstance(result[0], TextContent)
assert result[0].text == dt.isoformat()
assert result[0].text == f'"{dt.isoformat()}"'
async def test_image(self, tmp_path: Path):
mcp = FastMCP()

13
tests/tools/test_tool_manager.py
View file

@ -387,18 +387,7 @@ class TestCallTools:
assert isinstance(result, list)
assert len(result) == 1
assert isinstance(result[0], TextContent)
assert result[0].text == '["rex", "gertrude"]'
assert json.loads(result[0].text) == ["rex", "gertrude"]
result = await manager.call_tool(
"name_shrimp",
{"tank": '{"x": null, "shrimp": [{"name": "rex"}, {"name": "gertrude"}]}'},
)
assert isinstance(result, list)
assert len(result) == 1
assert isinstance(result[0], TextContent)
assert result[0].text == '["rex", "gertrude"]'
assert json.loads(result[0].text) == ["rex", "gertrude"]
assert result[0].text == '[\n "rex",\n "gertrude"\n]'
class TestToolSchema: