dynamodb-toolbox/dist/esm/schema/actions/parsePaths/expressPaths.js

Lightweight and type-safe query builder for DynamoDB and TypeScript.

import { isNumber } from '../../../utils/validation/isNumber.js';
import { Path } from '../utils/path.js';
export const expressPaths = (paths) => {
    let ProjectionExpression = '';
    const ExpressionAttributeNames = {};
    const tokens = {};
    let cursor = 1;
    paths.forEach((path, index) => {
        if (index > 0) {
            ProjectionExpression += ', ';
        }
        new Path(path).arrayPath.forEach((pathPart, index) => {
            if (isNumber(pathPart)) {
                ProjectionExpression += `[${pathPart}]`;
                return;
            }
            let token = tokens[pathPart];
            if (token === undefined) {
                token = `#p_${cursor}`;
                tokens[pathPart] = token;
                ExpressionAttributeNames[token] = pathPart;
                cursor++;
            }
            if (index > 0) {
                ProjectionExpression += '.';
            }
            ProjectionExpression += token;
        });
    });
    return { ProjectionExpression, ExpressionAttributeNames };
};