@nerdware/ddb-single-table/dist/esm/IOActions/setDefaults.js

A schema-based DynamoDB modeling tool, high-level API, and type-generator built to supercharge single-table designs!⚡

import { hasKey, isFunction } from "@nerdware/ts-type-safety-utils";
import { hasDefinedProperty } from "../utils/hasDefinedProperty.js";
/**
 * This `IOAction` applies any `"default"`s defined in the schema. Attribute
 * defaults are applied to an item when it either does not contain the attribute
 * as an own-property, or the attribute value is `null`/`undefined`.
 */
export const setDefaults = function (item, { schemaEntries, parentItem = item, ...ctx }) {
    // To avoid mutating the original item, create a new object to return
    const itemToReturn = { ...item };
    // Iterate over schemaEntries
    for (let i = 0; i < schemaEntries.length; i++) {
        const [attrName, attrConfig] = schemaEntries[i];
        // If a default is defined, and itemToReturn[attrName] is null/undefined, use the default
        if (hasKey(attrConfig, "default") && !hasDefinedProperty(itemToReturn, attrName)) {
            const attrDefault = attrConfig.default;
            // Check if "default" is a function, and if so, call it to get the "default" value
            const attrDefaultValue = isFunction(attrDefault) ? attrDefault(parentItem) : attrDefault;
            // Set the default value on the itemToReturn and parentItem
            itemToReturn[attrName] = attrDefaultValue;
            parentItem[attrName] = attrDefaultValue;
        }
        // Run recursively on nested attributes if parent value exists
        if (attrConfig.schema && hasKey(itemToReturn, attrName)) {
            itemToReturn[attrName] = this.recursivelyApplyIOAction(this.setDefaults, itemToReturn[attrName], {
                parentItem,
                ...ctx,
                schema: attrConfig.schema, // <-- overwrites ctx.schema with the nested schema
            });
        }
    }
    return itemToReturn;
};