public async Task <QueryResult <order> > ListAsync(ordersQuery query) { IQueryable <order> queryable = _context.orders .Include(p => p.Customer) .AsNoTracking(); // AsNoTracking tells EF Core it doesn't need to track changes on listed entities. Disabling entity // tracking makes the code a little faster if (query.CustomerId.HasValue && query.CustomerId > 0) { queryable = queryable.Where(p => p.CustomerId == query.CustomerId); } // Here I count all items present in the database for the given query, to return as part of the pagination data. int totalOrders = await queryable.CountAsync(); // Here I apply a simple calculation to skip a given number of items, according to the current page and amount of items per page, // and them I return only the amount of desired items. The methods "Skip" and "Take" do the trick here. List <order> orders = await queryable.Skip((query.Page - 1) *query.ItemsPerPage) .Take(query.ItemsPerPage) .ToListAsync(); // Finally I return a query result, containing all items and the amount of items in the database (necessary for client-side calculations ). return(new QueryResult <order> { Orders = orders, TotalOrders = totalOrders, }); }
private string GetCacheKeyForordersQuery(ordersQuery query) { string key = CacheKeys.ordersList.ToString(); if (query.CustomerId.HasValue && query.CustomerId > 0) { key = string.Concat(key, "_", query.CustomerId.Value); } key = string.Concat(key, "_", query.Page, "_", query.ItemsPerPage); return(key); }
public async Task <QueryResult <order> > ListAsync(ordersQuery query) { // Here I list the query result from cache if they exist, but now the data can vary according to the Customer ID, page and amount of // items per page. I have to compose a cache to avoid returning wrong data. string cacheKey = GetCacheKeyForordersQuery(query); var orders = await _cache.GetOrCreateAsync(cacheKey, (entry) => { entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(1); return(_orderRepository.ListAsync(query)); }); return(orders); }