How to use LinQ query to map the columns in an array?

Question

I would like to write LinQ query to the database by mapping the column names which are in an array.

I have the following column names in the array

string[] myColumns = {"CustID","FirstName","LastName","OrderID" };

Customer model has the following properties

public class Customer
{
    public int CustID { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

I am unable to map the columns to the Customer table using LinQ. I tried to implement the code as below code but I did not get the result.

var myResult=db.Customers.Select(x=>
new
{
myColumns[0]=x.CustID,
myColumns[1]=x.FirstName, 
myColumns[2]=x.LastNmae
}).ToList();

I appreciate you help

Here you are just replacing the values, not mapping them. Use dictionary if you are going to map or class if you are going to assign the values — Sajeetharan, Mar 22 '15 at 04:15

score 0 · Answer 1 · edited May 23 '17 at 10:10

Based on this discussion How to add dynamic member name and value to an instance of ExpandoObject class? I have found solutions to my question, Using below method should give you the dynamic members with their values

public static List<ExpandoObject> MapColumnsAndGetResult<T>(List<T> YourDataInList, string[] ColumnNames)
    {
        var result = new List<ExpandoObject>();
        foreach (var objClass in YourDataInList)
        {
            if (objClass != null)
            {
                var dynamicClass = new ExpandoObject() as IDictionary<string,object>;
                foreach (var prop in objClass.GetType().GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance))
                {
                    if (ColumnNames.Contains(prop.Name))
                    {
                        dynamicClass.Add(prop.Name, prop.GetValue(objClass, null));
                        result.Add((ExpandoObject)dynamicClass);
                    }
                }
            }
        }
        result = result.Distinct().ToList();
        return result;
    }

How to Use:

var dataModel = db.ChapterRepository.GetAll().ToList();
var myResult = MapColumnsAndGetResult(dataModel, myColumns);
foreach (var x in myResult)
        {
            foreach (var property in (IDictionary<String, Object>)x)
            {
                Console.WriteLine(property.Key + ": " + property.Value);
            }
        }

How to use LinQ query to map the columns in an array?

1 Answers1