Wrong page data with Entity Framework Core

.net-core c# entity-framework entity-framework-core

Question

Recently Im trying to upgrade My MVC project to dotnetCore project, while something went wrong in BaseService..

my former MVC code which works good:

public List<TEntity> FindList(Expression<Func<TEntity, bool>> predicate, Pagination pagination)
{
        using (var ent = new Entities())//  System.Data.Entity.DbContext
        {
            bool isAsc = pagination.sord.ToLower() == "asc";
            string[] order = pagination.sidx.Split(',');
            MethodCallExpression resultExp = null;
            var tempData = ent.Set<TEntity>().Where(predicate);
            foreach (string item in order)
            {
                string orderPart = item;
                orderPart = Regex.Replace(orderPart, @"\s+", " ");
                string[] orderArry = orderPart.Split(' ');
                string orderField = orderArry[0];
                if (orderArry.Length == 2)
                {
                    isAsc = orderArry[1].ToUpper() == "ASC";
                }
                var parameter = Expression.Parameter(typeof(TEntity), "t");
                var property = typeof(TEntity).GetProperty(orderField);
                if (property != null)
                {
                    var propertyAccess = Expression.MakeMemberAccess(parameter, property);
                    var orderByExp = Expression.Lambda(propertyAccess, parameter);
                    resultExp = Expression.Call(typeof(Queryable), isAsc ? "OrderBy" : "OrderByDescending", new Type[] { typeof(TEntity), property.PropertyType }, tempData.Expression, Expression.Quote(orderByExp));
                }
            }
            if (resultExp != null) tempData = tempData.Provider.CreateQuery<TEntity>(resultExp);
            pagination.records = tempData.Count();
            tempData = tempData.Skip<TEntity>(pagination.rows * (pagination.page - 1)).Take<TEntity>(pagination.rows).AsQueryable();
            return tempData.ToList();
        }
}

and the dotnetCore code:

public async Task<List<TEntity>> FindList(Expression<Func<TEntity, bool>> predicate, Pagination pagination)
{
        bool isAsc = pagination.sord.ToLower() == "asc";
        string[] order = pagination.sidx.Split(',');
        MethodCallExpression resultExp = null;
        var tempData = DbSet.Where(predicate);//a instance of Microsoft.EntityFrameworkCore.DbSet<TEntity> 
        foreach (string item in order)
        {
            string orderPart = item;
            orderPart = Regex.Replace(orderPart, @"\s+", " ");
            string[] orderArry = orderPart.Split(' ');
            string orderField = orderArry[0];
            if (orderArry.Length == 2)
            {
                isAsc = orderArry[1].ToUpper() == "ASC";
            }
            var parameter = Expression.Parameter(typeof(TEntity), "t");
            var property = typeof(TEntity).GetProperty(orderField);
            if (property != null)
            {
                var propertyAccess = Expression.MakeMemberAccess(parameter, property);
                var orderByExp = Expression.Lambda(propertyAccess, parameter);
                resultExp = Expression.Call(typeof(Queryable), isAsc ? "OrderBy" : "OrderByDescending", new Type[] { typeof(TEntity), property.PropertyType }, tempData.Expression, Expression.Quote(orderByExp));
            }
        }
        if (resultExp != null) tempData = tempData.Provider.CreateQuery<TEntity>(resultExp);
        pagination.records = tempData.Count();
        var list = await tempData.Skip<TEntity>(pagination.rows * (pagination.page - 1)).Take<TEntity>(pagination.rows).ToListAsync();
        return list;
}

and what strange is the code works well in just ordersorting or in just pagination;

but in both conditions(pagination&sorting) , the Second pagedata always went wrong(first pagedata always right);

page1:

page1

page2:

page2

1
0
2/14/2019 3:58:59 AM

Popular Answer

I dont know why but I replace the last 2 line code, the data comes right...

anyone can announce the mechanism?

        var list = await tempData.Skip<TEntity>(pagination.rows * (pagination.page - 1)).Take<TEntity>(pagination.rows).ToListAsync();
        return list;

as

        var list = tempData.ToAsyncEnumerable().Skip<TEntity>(pagination.rows * (pagination.page - 1)).Take<TEntity>(pagination.rows);
        return await list.ToList();
0
2/14/2019 7:03:10 AM


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