Build local tools without frontend

[kamushekp]

Hi @dosu! Please provide me an example of building custom components (tools) in code, so that I wouldn't be forced to re-launch front end every time to check if my components are written correctly: methods build_tool and run_model are nice

[dosubot[bot]]

Hey @kamushekp! I'm here to help you with any bugs, questions, or contributions you have. Let's work together to solve this!

To build and test custom components without using the frontend, you can follow these steps:

1. Create a Custom Component:
   Use the provided template to define your custom component. Here's a basic example:

   from langflow.custom import Component
   from langflow.inputs import MessageTextInput
   from langflow.template import Output
   from langflow.schema import Data
   
   class MyCustomComponent(Component):
       display_name = "My Custom Component"
       description = "A simple custom component example."
       icon = "icon-name"
   
       inputs = [
           MessageTextInput(
               name="input_text",
               display_name="Input Text",
               info="Text input for the component.",
           ),
       ]
   
       outputs = [
           Output(display_name="Output Data", name="output_data", method="process_data"),
       ]
   
       def process_data(self) -> Data:
           input_text = self.input_text
           result = f"Processed: {input_text}"
           self.status = result
           return Data(data={"result": result})

2. Use build_tool Method:
   The build_tool method constructs a Tool object from Python code, allowing you to dynamically execute and integrate custom functions. It handles imports, executes code, and creates a schema for function arguments using Pydantic models ^[1].

3. Implement run_model Method:
   This method should be implemented in your custom component to execute specific model logic. For example, in the GoogleSerperAPIComponent, it builds a wrapper and executes the model logic, returning the result ^[2].

4. Test Independently:
   You can write unit tests to verify your component's functionality. The codebase includes examples of testing custom components using pytest, focusing on properties and methods like build_template_config and get_function ^[3].

By following these steps, you can develop and test your custom components without needing to relaunch the frontend each time.

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