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Fix NameError with future annotations and Context/Depends parameters (#3243)
* Fix NameError with future annotations and Context/Depends parameters Closes #3238, closes #905 * chore: Update SDK documentation * Drop unnecessary pre-resolution of annotations Pydantic (even 2.11.7) uses __module__ not __globals__ to resolve annotations, so setting __module__ alone is sufficient. * chore: Update SDK documentation * Restore annotation pre-resolution for Pydantic compat The wrapper's __globals__ is read-only and points to dependencies.py, so some Pydantic versions use it instead of __module__ when resolving string annotations. Pre-resolving via get_type_hints on the original function ensures annotations are type objects before Pydantic sees them. * chore: Update SDK documentation --------- Co-authored-by: marvin-context-protocol[bot] <225465937+marvin-context-protocol[bot]@users.noreply.github.com>
This commit is contained in:
Jeremiah Lowin
GitHub
parent
1caf40eee8
commit
ea1328660e
3 changed files with 73 additions and 51 deletions
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@ -213,7 +213,7 @@ Handles:
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- Async wrapper function without injected parameters
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### `resolve_dependencies` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L696" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `resolve_dependencies` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L704" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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resolve_dependencies(fn: Callable[..., Any], arguments: dict[str, Any]) -> AsyncGenerator[dict[str, Any], None]
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@ -239,7 +239,7 @@ time, so all injection goes through the unified DI system.
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which will be filtered out)
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### `CurrentContext` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L837" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `CurrentContext` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L845" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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CurrentContext() -> Context
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@ -258,7 +258,7 @@ current MCP operation (tool/resource/prompt call).
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- `RuntimeError`: If no active context found (during resolution)
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### `CurrentDocket` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L880" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `CurrentDocket` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L888" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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CurrentDocket() -> Docket
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@ -278,7 +278,7 @@ automatically creates for background task scheduling.
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- `ImportError`: If fastmcp[tasks] not installed
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### `CurrentWorker` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L925" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `CurrentWorker` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L933" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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CurrentWorker() -> Worker
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@ -298,7 +298,7 @@ automatically creates for background task processing.
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- `ImportError`: If fastmcp[tasks] not installed
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### `CurrentFastMCP` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L967" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `CurrentFastMCP` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L975" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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CurrentFastMCP() -> FastMCP
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@ -316,7 +316,7 @@ This dependency provides access to the active FastMCP server.
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- `RuntimeError`: If no server in context (during resolution)
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### `CurrentRequest` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1002" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `CurrentRequest` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1010" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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CurrentRequest() -> Request
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@ -336,7 +336,7 @@ current HTTP request. Only available when running over HTTP transports
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- `RuntimeError`: If no HTTP request in context (e.g., STDIO transport)
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### `CurrentHeaders` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1038" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `CurrentHeaders` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1046" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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CurrentHeaders() -> dict[str, str]
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@ -353,7 +353,7 @@ safe to use in code that might run over any transport.
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- A dependency that resolves to a dictionary of header name -> value
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### `CurrentAccessToken` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1228" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `CurrentAccessToken` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1236" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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CurrentAccessToken() -> AccessToken
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@ -372,7 +372,7 @@ authenticated request. Raises an error if no authentication is present.
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- `RuntimeError`: If no authenticated user (use get_access_token() for optional)
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### `TokenClaim` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1280" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `TokenClaim` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1288" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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TokenClaim(name: str) -> str
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@ -406,7 +406,7 @@ Returned by ``get_task_context()`` when running inside a Docket worker.
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Contains identifiers needed to communicate with the MCP session.
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### `ProgressLike` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1065" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `ProgressLike` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1073" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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Protocol for progress tracking interface.
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@ -417,7 +417,7 @@ and Docket's Progress (worker context).
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**Methods:**
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#### `current` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1073" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `current` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1081" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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current(self) -> int | None
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@ -426,7 +426,7 @@ current(self) -> int | None
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Current progress value.
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#### `total` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1078" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `total` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1086" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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total(self) -> int
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@ -435,7 +435,7 @@ total(self) -> int
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Total/target progress value.
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#### `message` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1083" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `message` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1091" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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message(self) -> str | None
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@ -444,7 +444,7 @@ message(self) -> str | None
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Current progress message.
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#### `set_total` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1087" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `set_total` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1095" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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set_total(self, total: int) -> None
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@ -453,7 +453,7 @@ set_total(self, total: int) -> None
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Set the total/target value for progress tracking.
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#### `increment` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1091" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `increment` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1099" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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increment(self, amount: int = 1) -> None
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@ -462,7 +462,7 @@ increment(self, amount: int = 1) -> None
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Atomically increment the current progress value.
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#### `set_message` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1095" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `set_message` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1103" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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set_message(self, message: str | None) -> None
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@ -471,7 +471,7 @@ set_message(self, message: str | None) -> None
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Update the progress status message.
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### `InMemoryProgress` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1100" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `InMemoryProgress` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1108" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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In-memory progress tracker for immediate tool execution.
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@ -483,25 +483,25 @@ progress doesn't need to be observable across processes.
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**Methods:**
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#### `current` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1120" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `current` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1128" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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current(self) -> int | None
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```
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#### `total` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1124" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `total` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1132" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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total(self) -> int
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```
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#### `message` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1128" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `message` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1136" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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message(self) -> str | None
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```
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#### `set_total` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1131" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `set_total` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1139" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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set_total(self, total: int) -> None
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@ -510,7 +510,7 @@ set_total(self, total: int) -> None
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Set the total/target value for progress tracking.
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#### `increment` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1137" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `increment` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1145" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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increment(self, amount: int = 1) -> None
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@ -519,7 +519,7 @@ increment(self, amount: int = 1) -> None
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Atomically increment the current progress value.
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#### `set_message` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1146" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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#### `set_message` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1154" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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set_message(self, message: str | None) -> None
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@ -528,7 +528,7 @@ set_message(self, message: str | None) -> None
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Update the progress status message.
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### `Progress` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1151" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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### `Progress` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/dependencies.py#L1159" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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FastMCP Progress dependency that works in both server and worker contexts.
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@ -607,15 +607,23 @@ def without_injected_parameters(fn: Callable[..., Any]) -> Callable[..., Any]:
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result = await result
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return result
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# Set wrapper metadata (only parameter annotations, not return type)
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# Resolve string annotations (from `from __future__ import annotations`) using
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# the original function's module context. The wrapper's __globals__ points to
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# this module (dependencies.py) and is read-only, so some Pydantic versions
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# can't resolve names like Annotated or Literal from string annotations.
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try:
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resolved_hints = get_type_hints(fn, include_extras=True)
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except Exception:
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resolved_hints = getattr(fn, "__annotations__", {})
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wrapper.__signature__ = new_sig # type: ignore[attr-defined]
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wrapper.__annotations__ = {
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k: v
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for k, v in getattr(fn, "__annotations__", {}).items()
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if k not in exclude and k != "return"
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k: v for k, v in resolved_hints.items() if k not in exclude and k != "return"
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}
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wrapper.__name__ = getattr(fn, "__name__", "wrapper")
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wrapper.__doc__ = getattr(fn, "__doc__", None)
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wrapper.__module__ = fn.__module__
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wrapper.__qualname__ = getattr(fn, "__qualname__", wrapper.__qualname__)
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return wrapper
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@ -1,9 +1,9 @@
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from __future__ import annotations
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from typing import Any, cast
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from typing import Annotated, Any, Literal, cast
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import mcp.types
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import pytest
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from pydantic import Field
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from fastmcp import Context, FastMCP
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from fastmcp.client import Client
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@ -55,6 +55,20 @@ async def async_with_context(ctx: Context) -> str:
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return f"Async request: {ctx.request_id}"
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@fastmcp_server.tool
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def annotated_with_context(
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query: Annotated[str, Field(description="Search query")], ctx: Context
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) -> str:
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"""Tool using Annotated + Field with context."""
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return f"Result for: {query}"
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@fastmcp_server.tool
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def literal_with_context(mode: Literal["fast", "slow"], ctx: Context) -> str:
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"""Tool using Literal with context."""
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return f"Mode: {mode}"
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class TestFutureAnnotations:
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async def test_simple_with_context(self):
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async with Client(fastmcp_server) as client:
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@ -102,6 +116,23 @@ class TestFutureAnnotations:
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"Async request:" in cast(mcp.types.TextContent, result.content[0]).text
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)
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async def test_annotated_with_context(self):
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"""Test Annotated[str, Field(...)] works with Context and future annotations."""
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async with Client(fastmcp_server) as client:
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result = await client.call_tool(
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"annotated_with_context", {"query": "hello"}
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)
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assert (
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"Result for: hello"
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in cast(mcp.types.TextContent, result.content[0]).text
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)
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async def test_literal_with_context(self):
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"""Test Literal types work with Context and future annotations."""
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async with Client(fastmcp_server) as client:
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result = await client.call_tool("literal_with_context", {"mode": "fast"})
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assert "Mode: fast" in cast(mcp.types.TextContent, result.content[0]).text
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async def test_modern_union_syntax_works(self):
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"""Test that modern | union syntax works with future annotations."""
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# This demonstrates that our solution works with | syntax when types
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@ -138,33 +169,16 @@ class TestFutureAnnotations:
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)
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@pytest.mark.xfail(
|
||||
reason="Closure-scoped types cannot be resolved with 'from __future__ import annotations'. "
|
||||
"When using future annotations, all type annotations become strings that need to be evaluated "
|
||||
"using eval() in the function's global namespace. Types defined only in closure scope "
|
||||
"(like local imports or type aliases) are not available in the function's __globals__ "
|
||||
"and therefore cannot be resolved by get_type_hints()."
|
||||
)
|
||||
def test_closure_scoped_types_limitation():
|
||||
"""
|
||||
This test demonstrates that closure-scoped types don't work with future annotations.
|
||||
|
||||
The fundamental issue is that 'from __future__ import annotations' converts all
|
||||
annotations to strings, and those strings can only be resolved using the function's
|
||||
global namespace, not local variables from closures.
|
||||
"""
|
||||
|
||||
def create_failing_closure():
|
||||
# This import is only available in the closure scope
|
||||
def test_closure_scoped_types_with_builtins():
|
||||
"""Closure-scoped tools work when annotations only reference builtins."""
|
||||
|
||||
def create_closure():
|
||||
mcp = FastMCP()
|
||||
|
||||
@mcp.tool
|
||||
def closure_tool(value: str | None) -> str:
|
||||
"""This will fail because Optional can't be resolved from closure import."""
|
||||
return str(value)
|
||||
|
||||
return mcp
|
||||
|
||||
# This should raise an error during tool registration
|
||||
create_failing_closure()
|
||||
create_closure()
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue