Getting property value based on its column attribute value

问题

List<MyModel1> myModel1 = new List<MyModel1>();                    
MyUserModel myUserModel =  new MyUserModel();                    
List<MyModel2> myModel2 = new List<MyModel1>();
myModel1 = m_Service1.GetMyModelFields();
myUserModel = m_Service2.GetMyUserDetails();
myModel2 = (from myModel1Field in myModel1                        
             select new MyModel2 { FieldCaption = myModel1Field.FieldAlias, 
             FieldValue = "" }).ToList<MyModel2>();

myModel1Field.FieldAlias text will be same as value of one of the Column attribute of one of the property in myUserModel. So I have to search for the column atribute(Name) in myUserModel and get the corresponding property values and assign it to 'FieldValue'. If I can't find the value in myUserModel I can set 'FieldValue' as "NA"

One way to get the column attribute(Name) value of for a property is as below when I know the Property name.

myUserModel.GetType().GetProperty("FirstName").GetCustomAttributes(typeof(System.Data.Linq.Mapping.ColumnAttribute), false).Cast<System.Data.Linq.Mapping.ColumnAttribute>().Single().Name

But in my case Property name will not be known. I have to find the property based on the myModel1Field.FieldAlias value. How to go about this. Please suggest.

MyUserModel with one of it's properties

public class MyUserModel { 
[Column(Name = "first_name", DbType = "varchar")] 
public string FirstName { get; set; } 
}

Now if myModel1Field.FieldAlias is 'first_name' then I have to search in MyUserModel for a property with Column attribute(Name) as first_name. If it exists i have to set it's value to 'FieldValue'. Else set 'FieldValue' as "NA".

回答1:

If you want to get the value of a property and you only know the Name property of one of the ColumnAttribute attributes on it what you can do is this:

// Let's say you have the user model like so:
MyUserModel myUserModel = new MyUserModel { FirstName = "A", LastName = "B"};

// And then you want the value of the property that has the Column attribute Name "first_name"
string searchName = "first_name";    

// Using some lambda you can do this (I do not know how to do this in LINQ syntax, sorry)
object propertyValue = typeof (MyUserModel).GetProperties()
            .Where(p =>
                       {
                           var attrib = (ColumnAttribute)p
                               .GetCustomAttributes(typeof (ColumnAttribute), false)
                               .SingleOrDefault();
                           return (attrib != null && 
                                   attrib.Name.Equals(searchName));
                       })
            .Select(p => p.GetValue(myUserModel, null))
            .FirstOrDefault();

if(propertyValue != null)
{
    // Do whatever you want with the string "A" here - I suggest casting it to string! :-)
}

Is that what you want?

来源：https://stackoverflow.com/questions/8999749/getting-property-value-based-on-its-column-attribute-value

标签

linq

c#-4.0

columnattribute