read-config-ng/dist/resolve/override.js

Multi format configuration loader

import { put } from './deep.js';
const PROPERTY_SEPARATOR = '_';
/**
 * Override configuration values with environment variables
 * Environment variables should be prefixed with the marker (e.g., CONFIG_)
 * and use underscores to separate nested properties
 *
 * Example: CONFIG_database_host=localhost overrides config.database.host
 */
export function override(marker, config, values) {
    // If override is disabled, return config as-is
    if (!marker) {
        return config;
    }
    const envConfigPrefix = String(marker) + PROPERTY_SEPARATOR;
    // Find all environment variables that match the prefix
    Object.keys(values)
        .filter(name => {
        return name.startsWith(envConfigPrefix) && name.length > envConfigPrefix.length;
    })
        .forEach(name => {
        const value = values[name];
        if (value !== undefined) {
            // Extract property path from environment variable name
            const prop = name.substring(envConfigPrefix.length);
            const propPath = prop.split(PROPERTY_SEPARATOR);
            // Cast the value to appropriate type
            const castValue = castEnvironmentValue(value);
            // Set the value in the config object
            put(config, propPath, castValue);
        }
    });
    return config;
}
/**
 * Cast environment variable string to appropriate type
 */
function castEnvironmentValue(value) {
    const trimmed = value.trim();
    // Boolean values
    if (trimmed.toLowerCase() === 'true') {
        return true;
    }
    if (trimmed.toLowerCase() === 'false') {
        return false;
    }
    // Null/undefined values
    if (trimmed === 'null') {
        return null;
    }
    if (trimmed === 'undefined') {
        return undefined;
    }
    // Numeric values
    if (/^-?\d+$/.test(trimmed)) {
        return parseInt(trimmed, 10);
    }
    if (/^-?\d*\.\d+$/.test(trimmed)) {
        return parseFloat(trimmed);
    }
    // JSON objects/arrays
    if ((trimmed.startsWith('{') && trimmed.endsWith('}')) ||
        (trimmed.startsWith('[') && trimmed.endsWith(']'))) {
        try {
            return JSON.parse(trimmed);
        }
        catch {
            // If JSON parsing fails, return as string
            return value;
        }
    }
    // Default to string
    return value;
}
export default override;
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