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87 lines
3.6 KiB
Go
87 lines
3.6 KiB
Go
/*
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* Copyright 2025 CloudWeGo Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// This example shows how to configure the errorremover middleware on a ToolsNode
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// to catch errors during local tool invocation and return custom information.
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// Run: go run ./components/tool/middlewares/errorremover/example
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package errorremover
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import (
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"context"
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"fmt"
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"github.com/cloudwego/eino/compose"
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"github.com/cloudwego/eino/schema"
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)
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// removeErrorHandler is an error handler function that generates a string
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// describing the error that occurred during a tool call.
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func removeErrorHandler(ctx context.Context, in *compose.ToolInput, err error) string {
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// Formats the error message to include the tool name and the specific error content.
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return fmt.Sprintf("Failed to call tool '%s', error message: '%s'", in.Name, err.Error())
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}
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// Invokable creates a middleware endpoint for non-streaming (invokable) tools.
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// It intercepts the tool's execution. If the tool returns an error, it calls the
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// error handler and returns its result as a successful ToolOutput,
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// effectively suppressing the original error.
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func Invokable(next compose.InvokableToolEndpoint) compose.InvokableToolEndpoint {
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return func(ctx context.Context, in *compose.ToolInput) (*compose.ToolOutput, error) {
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// Proceed with the next middleware or the actual tool execution.
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output, err := next(ctx, in)
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// If an error occurs during execution.
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if err != nil {
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// Generate a custom error message using removeErrorHandler.
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result := removeErrorHandler(ctx, in, err)
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// Wrap the custom message in a successful ToolOutput and return it,
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// with the error itself set to nil.
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return &compose.ToolOutput{Result: result}, nil
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}
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// If there was no error, return the original output.
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return output, nil
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}
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}
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// Streamable creates a middleware endpoint for streaming tools.
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// It intercepts the tool's execution. If the tool returns an error, it calls the
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// error handler and returns its result as a new stream containing a single successful item.
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// This effectively replaces the error with a successful stream output.
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func Streamable(next compose.StreamableToolEndpoint) compose.StreamableToolEndpoint {
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return func(ctx context.Context, in *compose.ToolInput) (*compose.StreamToolOutput, error) {
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// Proceed with the next middleware or the actual tool execution.
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streamOutput, err := next(ctx, in)
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// If an error occurs during execution.
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if err != nil {
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// Generate a custom error message using removeErrorHandler.
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result := removeErrorHandler(ctx, in, err)
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// Return the new stream as a successful output.
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return &compose.StreamToolOutput{Result: schema.StreamReaderFromArray([]string{result})}, nil
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}
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// If there was no error, return the original stream output.
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return streamOutput, nil
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}
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}
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// Middleware constructs and returns a compose.ToolMiddleware.
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// This middleware is designed to catch errors from tool executions and replace them
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// with a custom, successful output.
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func Middleware() compose.ToolMiddleware {
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return compose.ToolMiddleware{Invokable: Invokable, Streamable: Streamable}
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}
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