How to Use Dictionary to sort the list in asp.net web api

Question

I have Book list. That i want to sort in order like Publisher, AuthorfirstName ,AuthorSecondName, Title,Price using dictionary in Asp.net Web api.How to add key value pair combination here ?

My Web Api Code

public IEnumerable <BookViewModel> GetBook()
{
ISqlDBHelper sqlDBHelper = new SqlDBHelper();
BookViewModel bvm = new BookViewModel();
List<BookViewModel> bklst = new List<BookViewModel>();
Dictionary<int, string> bk = new Dictionary<int, string>();
DataTable dt = sqlDBHelper.ExecuteSelectCommand("uspBooklst", CommandType.StoredProcedure);
if (dt.Rows.Count > 0)
{
foreach (DataRow row in dt.Rows)
{
if (!DBNull.Value.Equals(row["UID"]))
{
bvm.UID = Convert.ToInt32(row["UID"]);
}
if (!DBNull.Value.Equals(row["Publisher"]))
{
bvm.Publisher = row["Publisher"].ToString();
}
if (!DBNull.Value.Equals(row["AuthorFirstName"]))
{
bvm.AuthorFirstName = row["AuthorFirstName"].ToString();
}
if (!DBNull.Value.Equals(row["AuthorLastName"]))
{
bvm.AuthorLastName = row["AuthorLastName"].ToString();
}
if (!DBNull.Value.Equals(row["Title"]))
{
bvm.Title = row["Title"].ToString();
}
if (!DBNull.Value.Equals(row["Price"]))
{
bvm.Price = Convert.ToDecimal(row["Price"]);
}

bklst.Add(bvm);
}
}

return bklst;
}

Output

In Api Output the order is not in the correct format which i am expecting so i plan to use dictionary but i donno how to use it in Asp.net Web api .Help me to resolve the issue.

Prasad Raveendran · Answer

I have provided a sample code to use Dictionary instead of List. public IEnumerable GetBook() { ISqlDBHelper sqlDBHelper = new SqlDBHelper(); DataTable dt = sqlDBHelper.ExecuteSelectCommand("uspBooklst", CommandType.StoredProcedure); Dictionary bookDict = new Dictionary (); foreach (DataRow row in dt.Rows) { BookViewModel bvm = new BookViewModel(); bvm.UID = GetValueOrDefault (row, "UID"); bvm.Publisher = GetValueOrDefault (row, "Publisher"); bvm.AuthorFirstName = GetValueOrDefault (row, "AuthorFirstName"); bvm.AuthorLastName = GetValueOrDefault (row, "AuthorLastName"); bvm.Title = GetValueOrDefault (row, "Title"); bvm.Price = GetValueOrDefault (row, "Price"); string key = GetCompositeKey(bvm.Publisher, bvm.AuthorFirstName, bvm.AuthorLastName, bvm.Title, bvm.Price); if (!bookDict.ContainsKey(key)) { bookDict.Add(key, bvm); } } List bklst = bookDict.Values.ToList(); return bklst; } private T GetValueOrDefault (DataRow row, string columnName) { if (!DBNull.Value.Equals(row[columnName])) { return Convert.ChangeType(row[columnName], typeof(T)); } return default(T); } private string GetCompositeKey(params object[] values) { return string.Join("|", values); }

Prasad Raveendran · Answer

I have updated another sample code with column sort. please have a look and confirm

Sneha K · Answer

Hi Prasad Let me check you solution and let you know

Prasad Raveendran · Answer

Please take a look at the sample attached. I believe, its sorting as expected. you are expecting the sorting as below. Sort by Publisher, Author last name, authorfirst name then title. as you are starting the sort with Publisher first, always the records will be displayed based on the Publisher. if you are satifisifed with this result, please do let me know the expected output.

Prasad Raveendran · Answer

did you try my first sample code where I have included the sorting on List?

Sneha K · Answer

Hi Prasad This is my table structure I want to write the api method to return a sorted list of these by Publisher, Author last name, authorfirst name then title. And yesterday i cleared the error but still i didnt get the values in the sorted order

Prasad Raveendran · Answer

Please use the modified method as give me below and let me know if you are facing the issue private T GetValueOrDefault (DataRow row, string columnName) { if (!DBNull.Value.Equals(row[columnName])) { object value = row[columnName]; return (T)Convert.ChangeType(value, typeof(T)); } return default(T); } I would request you to share the sample data so that I can take a look. I would request you share your expected output as well.

Sneha K · Answer

Hi Prasath Still the order is not formed as per my expectation Please look below image

Sneha K · Answer

Hi Prasad Thanks for the solution currently i am getting one error .Please check below

Prasad Raveendran · Answer

I have refactored the code as below I simplified the null value checks by utilizing the GetValueOrDefault method and removed the redundant ToString() calls public IEnumerable GetBook() { ISqlDBHelper sqlDBHelper = new SqlDBHelper(); DataTable dt = sqlDBHelper.ExecuteSelectCommand("uspBooklst", CommandType.StoredProcedure); List bklst = new List (); foreach (DataRow row in dt.Rows) { BookViewModel bvm = new BookViewModel(); bvm.UID = GetValueOrDefault (row, "UID"); bvm.Publisher = GetValueOrDefault (row, "Publisher"); bvm.AuthorFirstName = GetValueOrDefault (row, "AuthorFirstName"); bvm.AuthorLastName = GetValueOrDefault (row, "AuthorLastName"); bvm.Title = GetValueOrDefault (row, "Title"); bvm.Price = GetValueOrDefault (row, "Price"); bklst.Add(bvm); } bklst = bklst.OrderBy(b => b.Publisher) .ThenBy(b => b.AuthorFirstName) .ThenBy(b => b.AuthorLastName) .ThenBy(b => b.Title) .ThenBy(b => b.Price) .ToList(); return bklst; } private T GetValueOrDefault (DataRow row, string columnName) { if (!DBNull.Value.Equals(row[columnName])) { return Convert.ChangeType(row[columnName], typeof(T)); } return default(T); } In the refactored code: After populating the list with BookViewModel objects, I use the LINQ OrderBy and ThenBy methods to sort the list based on the specified properties in the desired order. The OrderBy method is used to sort the list by the Publisher property. The ThenBy method is used to perform subsequent sorting on the AuthorFirstName , AuthorLastName , Title , and Price properties. Finally, I convert the sorted sequence back to a list using the ToList method. The rest of the code remains the same as before Please do let me know your thoughts. I'm wondering the why you need to Dictionary for sorting? Please provide more details on this

How to Use Dictionary to sort the list in asp.net web api

Answers (10)