@mysql/xdevapi/lib/DevAPI/ProjectedDocumentExprStr.js

MySQL Connector/Node.js - A Node.js driver for MySQL using the X Protocol and X DevAPI.

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'use strict';

const ExprParser = require('../ExprParser');
const Expr = require('./Expr');

/**
 * Factory function to create instances of an informal type that encapsulates
 * a set of projected search document fields and optional aliases defined as
 * a string or an X DevAPI expression (computed or not).
 * @private
 * @module ProjectedDocumentExprStr
 */

const parser = ExprParser({ type: ExprParser.Type.PROJECTED_SEARCH_EXPR });

/**
 * A document field name and optional alias to include as part of a result set.
 * @typedef {string|module:Expr} ProjectedDocumentExprStr
 * @global
 * @example
 * // string
 * foo.bar.baz as path
 * foo[2].bar as path
 * foo.*.bar as path
 * // X DevAPI expression
 * mysqlx.expr('foo.bar.baz as path')
 * mysqlx.expr('foo[2].bar as path')
 * mysqlx.expr('foo.*.bar as path')
 * mysqlx.expr('{ "foobar": concat(foo, bar) }')
 */

/**
 * One or more document field names and corresponding optional aliases.
 * @typedef {ProjectedDocumentExprStr|ProjectedDocumentExprStr[]} ProjectedDocumentsExprStr
 * @global
 */

/**
 * @private
 * @alias module:ProjectedDocumentExprStr
 * @param {ProjectedDocumentExprStr} value - A String or X DevAPI expression
 * instance containing a field name and an optional alias or a computed
 * projection definition.
 * @returns {module:ProjectedDocumentExprStr}
 */
function ProjectedDocumentExprStr (value) {
    return {
        /**
         * Parses the underlying projected search expression and return
         * the result.
         * @private
         * @function
         * @name module:ProjectedDocumentExprStr#getValue
         * @returns {ExpressionTree} An Object that represents an expression
         * tree that results from parsing a given X DevAPI projected search
         * expression string.
         */
        getValue () {
            const original = Expr({ value }).getExpressionString();
            const projectedDocumentExpr = parser.parse(original);
            const { source, alias } = projectedDocumentExpr;

            // If we are dealing with a computed projection (which is
            // specified as a jsonDoc expression), we should not set
            // an alias.
            if (!alias && source.type !== 'jsonDoc') {
                projectedDocumentExpr.alias = original;
            }

            return projectedDocumentExpr;
        }
    };
}

module.exports = ProjectedDocumentExprStr;