wj-config/out/merge.js

Javascript configuration module for NodeJS and browser frameworks such as React that works like ASP.net configuration where data sources are specified (usually JSON files) and environment variables can contribute/overwrite values by following a naming con

import { forEachProperty, isArray, isConfigNode } from "./helpers.js";
function mergeTwo(obj1, obj2, trace) {
    let recursiveTrace;
    // Add the properties of obj2.
    forEachProperty(obj2, (key, value) => {
        const value1 = obj1[key];
        if (value1 !== undefined) {
            // If it is a scalar/array value, the value in object 2 must also be a scalar or array.
            // If it is an object value, then value in object 2 must also be an object.
            if (isConfigNode(value1) && !isConfigNode(value)) {
                throw new Error(`The destination value of property "${key}" is an object, but the second object is not providing an object value.`);
            }
            if (!isConfigNode(value1) && isConfigNode(value)) {
                throw new Error(`The destination value of property "${key}" is a scalar/array value, but the second object is not providing a scalar/array value.`);
            }
            if (isConfigNode(value1)) {
                // Recursively merge obj2 into obj1.
                if (trace) {
                    recursiveTrace = {
                        trace: (trace.trace[key] = trace.trace[key] ?? {}),
                        dataSource: trace.dataSource
                    };
                }
                mergeTwo(value1, value, recursiveTrace);
            }
            else {
                obj1[key] = value;
                if (trace) {
                    trace.trace[key] = trace.dataSource.trace();
                }
            }
        }
        else {
            if (trace && isConfigNode(value)) {
                // Must trace, so merge.
                obj1[key] = {};
                recursiveTrace = {
                    trace: (trace.trace[key] = trace.trace[key] ?? {}),
                    dataSource: trace.dataSource
                };
                mergeTwo(obj1[key], value, recursiveTrace);
            }
            else {
                obj1[key] = value;
                if (!isConfigNode(value) && trace) {
                    // Update the trace.
                    trace.trace[key] = trace.dataSource.trace();
                }
            }
        }
    });
    return obj1;
}
export default function merge(objects, dataSources) {
    if (!isArray(objects)) {
        throw new Error('The provided value is not an array of objects.');
    }
    // There must be at least one object.
    if (objects.length === 0 || !isConfigNode(objects[0]) || objects[0] === null || objects[0] === undefined) {
        throw new Error('The first element of the array is required and must be a suitable configuration object.');
    }
    // If there are data sources, the number of these must match the number of provided objects.
    if (dataSources && objects.length !== dataSources?.length) {
        throw new Error('The number of provided objects differs from the number of provided data sources.');
    }
    let result = {};
    let trace;
    if (dataSources) {
        trace = {
            trace: {},
            dataSource: dataSources[0]
        };
    }
    for (let idx = 0; idx < objects.length; ++idx) {
        let nextObject = objects[idx];
        // If null or undefined, just substitute for an empty object.
        if (nextObject === null || nextObject === undefined) {
            nextObject = {};
        }
        else if (!isConfigNode(nextObject)) {
            throw new Error(`Configuration object at index ${idx} is not of the appropriate type.`);
        }
        if (trace) {
            trace.dataSource = dataSources[idx];
        }
        mergeTwo(result, nextObject, trace);
    }
    if (trace) {
        result._trace = trace.trace;
    }
    return result;
}