Add Filters and Sort Feature to your search API

snippet.js

validateFilterAndSort(req,res,next)
    {

        let query = req.query['q'];

        // Let destructure our query.
        let {filter,sort} = req.query;


        // Let's limit the possible column user can filter by.
        const FilterableColumns = ['books_count', 'ratings_count', 'original_publication_year', 'original_publication_year', 'original_publication_day'];

        if(filter != undefined)
        {
            // Validate Filter Column and fail if invalid
            if (!FilterableColumns.includes(filter)) {
                res.status(500).json(super.sendResponse('SEARCH_FILTERING_ERROR', "You cannot filter by "+ filter));
            }

        }


        // Let's limit the possible column user can sort by
        const sortableColumns = ['id', 'ratings_count', 'original_publication_year', 'original_publication_year', 'original_publication_day'];

        if(sort)
        {
            // We support the order of sorting. So lets destructure by ":" delimiter
            let [column, order] = sort.split(':');

            if (!sortableColumns.includes(column)) {
                res.status(500).json(super.sendResponse('SEARCH_SORTING_ERROR', "You cannot sort by "+ sort));
            }

            if (order === undefined) {
                order = 'asc';
            }

            if (order !== 'asc' && order !== 'desc') {
                res.status(500).json(super.sendResponse('SEARCH_SORTING_ERROR', "You have an invalid sort order "+ order));
            }
        }

        return (query) ? query : "books"; // Always return original query or validated query if filter or sort is present
    }