Running Calculations (fdm-calculator)

The @svenvw/fdm-calculator package provides functions to perform various agronomic calculations based on data stored within the FDM structure. This allows for deriving insights and recommendations from the recorded farm data.

Overview

The calculator package typically takes data retrieved using fdm-core as input, or uses fdm-core functions internally to fetch data before performing calculations.

Example: Calculating Total Fertilizer Dose for a Field

The fdm-calculator package exports a convenient function getDoseForField that calculates the cumulative N, P2O5, K2O, and workable N doses applied to a specific field. It handles fetching the necessary fertilizer applications and fertilizer details using fdm-core internally.

import { 
    createFdmServer, 
    // Import needed types
    FdmServerType, 
    PrincipalId 
} from '@svenvw/fdm-core'; 
import { 
    getDoseForField // Import the function from fdm-calculator
} from '@svenvw/fdm-calculator'; 

// --- Assume Initialization ---
// Replace with your actual initialization logic
declare const fdm: FdmServerType; 
declare const principalId: PrincipalId; 
// --- End Initialization ---

async function calculateFieldDose(fieldId: string) {
    console.log(`Attempting to calculate total dose for field ${fieldId}...`);
    try {
        // Call the calculator function directly, providing the fdm instance,
        // the user performing the action, and the target field ID.
        const totalDose = await getDoseForField({
            fdm: fdm,
            principal_id: principalId,
            b_id: fieldId 
        }); 

        console.log(`Calculated dose for field ${fieldId}:`, totalDose);
        // Example output format (based on Dose type):
        // { p_dose_n: 120.5, p_dose_nw: 85.3, p_dose_p2o5: 60.0, p_dose_k2o: 90.0 }
        return totalDose;

    } catch (error) {
        console.error(`Error calculating dose for field ${fieldId}:`, error);
        // Handle error appropriately
    }
}

// Example Usage:
// const fieldId = 'your_field_id'; // Get this from fdm-core, e.g., via getFields
// calculateFieldDose(fieldId);

This example demonstrates the general workflow using the getDoseForField function:

1. Initialize your fdm-core instance (fdm).
2. Have the principalId of the user making the request.
3. Call the specific calculation function from @svenvw/fdm-calculator (e.g., getDoseForField) with the required parameters.
4. The function handles fetching the necessary underlying data via fdm-core and returns the calculated result.

Refer to the API Reference section or the source code for details on other available calculation functions, their specific parameters, and return types.