When dealing with really small apps and the sqlbulkcopy, I normally create datatables by either using a FILL on an empty datatable OR I just type out something like this
DataTable dtGrps = new DataTable();
dtGrps.Columns.Add("objectGuid", typeof(Guid));
dtGrps.Columns.Add("DN", typeof(string));
dtGrps.Columns.Add("CN", typeof(string));
dtGrps.Columns.Add("groupType", typeof(string));
dtGrps.Columns.Add("description", typeof(string));
dtGrps.Columns.Add("whenCreated", typeof(string));
dtGrps.Columns.Add("whenChanged", typeof(string));
but it occurred to me that surly there is a built in way (non EF or Linq) to create all the code above by some drag in drop method. I mean I am using VS2017, surely MS has added this feature and I have just missed it is all.
So does this exist?
This is a very rough implementation, just intended as a starting point because my goal here isn't to write a new library. It could use a lot of optimization. But you can use strongly typed objects, use reflection to generate a DataTable based on the objects, and then use SqlBulkCopy to insert that.
using System;
using System.Collections.Generic;
using System.Data;
namespace StronglyStypedSqlBulkCopy
{
class Program
{
static void Main(string[] args)
{
List<Car> cars = GetSampleData();
DataTable dataTable = ConvertToDataTable(cars);
Console.WriteLine("Press any key to exit.");
Console.ReadKey(true);
}
public static List<Car> GetSampleData()
{
return new List<Car> {
new Car { Id = 1, Make = "Toyota", Model = "Tacoma", DateOfManufacture = DateTime.Now.AddDays(-1) },
new Car { Id = 2, Make = "Ford", Model = "Raptor", DateOfManufacture = DateTime.Now.AddDays(-2) },
new Car { Id = 3, Make = "Ram", Model = "1500", DateOfManufacture = DateTime.Now.AddDays(-3) }
};
}
public static DataTable ConvertToDataTable<T>(IEnumerable<T> objects)
{
var properties = objects.GetType().GetGenericArguments()[0].GetProperties();
var table = new DataTable();
foreach (var property in properties)
{
var columnName = property.Name; //may want to get from attribute also
//probably want to define an explicit mapping of .NET types to SQL types, and allow an attribute to specifically specify the SQL type
table.Columns.Add(columnName, property.PropertyType);
}
//probably want to cache the mapping from above in a real implementation
foreach (var obj in objects)
{
var row = table.NewRow();
foreach (var property in properties)
{
var columnName = property.Name; //may want to get from attribute also
var propertyValue = property.GetValue(obj);
row[columnName] = propertyValue;
}
table.Rows.Add(row);
}
return table;
}
}
public class Car
{
public int Id { get; set; }
public string Make { get; set; }
public string Model { get; set; }
public DateTime DateOfManufacture { get; set; }
}
}
Once you have a nice implementation of ConvertToDataTable, it's simply a matter of defining strongly typed classes, which are much easier to work with than raw DataTables.
Related
I am a little bit confused about how to read data from Excel. I am trying to import Excel for updating product list, I create an Excel model; I added all basic properties like name, price, quantity, etc. into this model. I will read all Excel and map into this model. That's ok, then I will give this model to EF Core 5 to save to SQL Server.
public class ExcelModel
{
public string Name { get; set }
public int Price { get; set }
public int Quantity { get; set }
}
I have a problem with product options. According to my DB schema, I have one table of products, one for options, one for option values, one for productOptionRelation.
Can you suggest another solution way or just solve on my way?
My colleges did this created field corresponding to values. like option1 and optionValue1, option2 and optionValue2 many of them, because each product could have many options. Model look like that, 20 option and 20 value was declared here and they manually map all these
For a temporary solution, I limited this option up to 5 and I created an list. and encapsulate all of them into list
public class ExcelOptionViewModel
{
public string Option { get; set; }
public string Value { get; set; }
}
This is my temp model, I encapsulated like that.
public IList<ExcelOptionViewModel> OptionModels { get; set; } = new List<ExcelOptionViewModel>();
public string Option1
{
get { return OptionModels[0].Option; }
set
{
this.OptionModels.Insert(0, new ExcelOptionViewModel { Option = value });
}
}
public string Option1Value
{
get { return OptionModels[0].Value; }
set { this.OptionModels[0].Value = value; }
}
This would be unlimited, You should enter how much you want
I have 2 solutions still I am researching one is, creating a method inside the excelviewmodel, this method will add all options and values into a list or I will use reflection, I am looking something like underlying type I will all option and values this underlying base type or something, when property loop came here, checking the type and assign all option1,option2,option3 or name like that properties to List<string> options, and same for the option values. I will use reading like option[0] and optionvalue[0]
Excel column names must be different because I read excel and turn it into datatable. Datatable column names must be different, it's not valid for reading into datatable
I used basically excel to data table function I can't remember but probably I found it in StackOverflow. Also, I added a feature there If some cell is null it will miss.
public List<T> ConvertDataTableToList<T>(DataTable dt)
{
//datatable clomun names
var columnNames = dt.Columns.Cast<DataColumn>().Select(c => c.ColumnName.ToLower()).ToList();
//selection properties equals to columnnames because I dont want loop for all props
var properties = typeof(T).GetProperties().Where(prp => columnNames.Any(t => t.ToLower() == prp.Name.ToLower()));
return dt.AsEnumerable().Select(row =>
{
var objT = Activator.CreateInstance<T>();
foreach (var pro in properties)
{
try
{
if (row[pro.Name] != DBNull.Value)
pro.SetValue(objT, row[pro.Name], null);
else
pro.SetValue(objT, null, null);
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
}
return objT;
}).ToList();
}
I am looking something here when option1 or option2 comes here it would put this into a list
Also in my dt to model converter I dont want to use If but if some data value is null It throws an error which cant convert from dbnull value. If you have a suggest for it I would like release if condition :)
When All done I will map this excelviewmodel to product model something like this
foreach (var prop in SideParams.columns)
{
var source = row.GetType().GetProperty(prop);
var destination = product.GetType().GetProperty(prop);
if (destination != null && source.GetValue(row) != null)
{
Type t = Nullable.GetUnderlyingType(destination.PropertyType) ?? destination.PropertyType;
object safeValue = Convert.ChangeType(source.GetValue(row), t);
destination.SetValue(product, safeValue);
}
}
I saw something here
https://learn.microsoft.com/en-us/dotnet/api/system.reflection.bindingflags?view=net-6.0
it about binding flangs when reflecting model. "Specifies flags that control binding and the way in which the search for members and types is conducted by reflection." If there is way I can redirect option(1-2-3-4-5-6...) to list options
thanks for the help I solved my problem. If you need something like that, my solution is;
As you know OptionModels is what I created before, AddOptipns function is a new one I use for add data to list,
The function work with the ref, otherwise it must be static, if I turn it static, option models also must be static, so I can't access the list.
public IList<ExcelOptionViewModel> OptionModels { get; set; } = new List<ExcelOptionViewModel>();
public void AddOptions(ref String option, ref String value)
{
OptionModels.Add(new ExcelOptionViewModel { Option = option.Trim(), Value = value.Trim() });
}
And also add some new parts to convert model function,
calling that AddOptions method with reflection, I got an example from here
https://learn.microsoft.com/en-us/dotnet/api/system.reflection.bindingflags?view=net-6.0
I was inspired by the swap example there.
public List<T> ConvertDataTableToList<T>(DataTable dt)
{
var columnNames = dt.Columns.Cast<DataColumn>().Select(c => c.ColumnName.ToLower()).ToList();
//selection properties equals to columnnames because I dont want loop for all props
var type = typeof(T);
var properties = type.GetProperties().Where(prp => columnNames.Any(t => t.ToLower() == prp.Name.ToLower())).ToList();
var productOptions = columnNames.Where(x => x.Contains("option")).ToList() ?? new List<string>();
return dt.AsEnumerable().Select(row =>
{
var objT = Activator.CreateInstance<T>();
foreach (var pro in properties)
{
try
{
if (row[pro.Name] != DBNull.Value)
pro.SetValue(objT, row[pro.Name], null);
else
pro.SetValue(objT, null, null);
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
}
for (var i = 0; i < productOptions.Count(); i += 2)
{
object[] argValues = new object[] { row[productOptions[i]].ToString(), row[productOptions[i + 1]].ToString() };
String[] argNames = new String[] { "option", "value" } ;
var method = type.GetMethod("AddOptions");
method.Invoke(objT, argValues);
}
return objT;
}).ToList();
}
here is the added data :)
i am trying to convert a list to dataTable and then save it to the database , but i am facing a problem . I get an error that column Mapping does not match .
This is my List
public static class Program
{
static Logger _myLogger = LogManager.GetCurrentClassLogger();
public class Student
{
public int int { get; set; }
public string name { get; set; }
public string email { get; set; }
public string phoneNumber { get; set; }
public virtual ICollection<tblStudentCourses> tblStudentCourses { get; set; }
}
List<Student> student = new List<Student>();
This is the extensions that i am using
public static DataTable AsDataTable<T>(this IList<T> data)
{
DataTable dataTable = new DataTable(typeof(T).Name);
//Get all the properties
PropertyInfo[] Props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (PropertyInfo prop in Props)
{
//Defining type of data column gives proper data table
var type = (prop.PropertyType.IsGenericType && prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>) ? Nullable.GetUnderlyingType(prop.PropertyType) : prop.PropertyType);
//Setting column names as Property names
dataTable.Columns.Add(prop.Name, type);
}
foreach (T item in data)
{
var values = new object[Props.Length];
for (int i = 0; i < Props.Length; i++)
{
//inserting property values to datatable rows
values[i] = Props[i].GetValue(item, null);
}
dataTable.Rows.Add(values);
}
//put a breakpoint here and check datatable
return dataTable;
}
This how i am calling the extension
using (var connection = new SqlConnection(ConfigurationManager.AppSettings["connectionString"]))
{
connection.Open();
SqlTransaction transaction = connection.BeginTransaction();
using (var bulkCopy = new SqlBulkCopy(connection, SqlBulkCopyOptions.Default, transaction))
{
bulkCopy.DestinationTableName = "dbo.Student";
bulkCopy.WriteToServer(student.AsDataTable());
connection.Close();
}
transaction.Commit();
}
The error :
The given ColumnMapping does not match up with any column in the source or destination
Use FastMember's ObjectReader to create an IDataReader on top of any collection, eg :
var student = new List<Student>();
...
using(var bcp = new SqlBulkCopy(connection))
using(var reader = ObjectReader.Create(student, "Id", "Name", "Email","PhoneNumber"))
{
bcp.DestinationTableName = "SomeTable";
bcp.WriteToServer(reader);
}
SqlBulkCopy can use either a DataTable or IDataReader. ObjectReader.Create creates an object that wraps any collection and exposes it through an IDataReader interface that can be used with SqlBulkCopy.
It's also possible to use Linq-to-Dataset's CopyToDataTable or MoreLinq's ToDataTable extension methods to create a DataTable from an IEnumerable. These will have to read the entire IEnumerable though and cache all data in the DataTable. This can be expensive if there are a lot of rows.
ObjectReader on the other hand doesn't need to cache anything
The error The given ColumnMapping does not match up with any column in the source or destination
happen usually for 3 causes:
You didn't provide any ColumnMappings, and there is more column in the source than in the destination.
You provided an invalid column name for the source.
You provided an invalid column name for the destination.
In your case, you didn't supply column mapping. Here is an online example similar to your scenario: https://dotnetfiddle.net/WaeUi9
To fix it:
Provide a ColumnMappings
For example: https://dotnetfiddle.net/Zry2tb
More information about this error can be found here: https://sqlbulkcopy-tutorial.net/columnmapping-does-not-match
If you are able to read data in data table then change your code like below
bulkCopy.DestinationTableName = "dbo.Student";
bulkCopy.ColumnMappings.Add("<list field name>", "<database field name>");
//Map all your column as above
bulkCopy.WriteToServer(dataTable);
I hope this works for your problem.
I am trying to serialize nested objects using reflection. I am able to do this fine for properties containing a single value, but I am having trouble with list type properties that contain another class.
In the code sample below I have a class Dish which contains a list of of Recipe classes as a property, which itself contains a list of Step classes.
I am able to get the PropertyInfo of the List property, but when I try to get the contents of it by invoking the get method, I get a simple object back, not a List of e.g. Steps:
var listObjects = property.GetGetMethod().Invoke(dish, null);
I managed to cast that into a List of objects like this:
List<object> listValues = ( listObjects as IEnumerable<object>).Cast<object>().ToList();
Now at least I can iterate over this List, but I cannot get the acutal properties of the original classes like the step description.
So I know the type of the List via property.PropertyType.GenericTypeArguments.First(), but its at runtime. I am thinking on how to perform a proper cast to transform my List<object> into a conrete type like List<Step>.
What I want to achieve: Serialize all property values of dish and all its attached Lists of objects.
I appreciate any ideas.
using System;
using System.Linq;
using System.Collections.Generic;
public class Program
{
public static void Main()
{
var dish = new Dish(){
Recipes = new List<Recipe>(){
new Recipe(){
RecipeName = "Preparation",
Steps = new List<Step>(){
new Step(){
Description = "Prepare Stuff",
}
}
},
new Recipe(){
RecipeName = "Main Course",
Steps = new List<Step>(){
new Step(){
Description = "Do this",
},
new Step(){
Description = "Then do that",
}
}
}, }, };
var serializer = new Serializer();
serializer.SerializeDish(dish);
}
}
public class Serializer
{
public void SerializeDish(Dish dish)
{
var dishType = typeof (Dish);
var listProps = dishType.GetProperties().Where(x => (x.PropertyType.IsGenericType && x.PropertyType.GetGenericTypeDefinition() == typeof (List<>)));
foreach (var property in listProps)
{
var propertyGetMethod = property.GetGetMethod();
var listObjects = propertyGetMethod.Invoke(dish, null);
Console.WriteLine("Name:"+property.Name + " " + "List-Type:"+property.PropertyType.GenericTypeArguments.First());
//Here its getting fuzzy
List<object> listValues = ( listObjects as IEnumerable<object>).Cast<object>().ToList();
foreach ( var item in listValues ) {
Console.WriteLine(item);
}
}
}
}
public class Dish
{
public List<Recipe> Recipes {get;set;}
}
public class Recipe
{
public string RecipeName{get;set;}
public List<Step> Steps {get;set;}
}
public class Step
{
public string Description {get;set;}
}
I'm trying to create a controller that could get Stored Procedure result without column definition like without model.
I'm thinking that if I can get the column names, I can create a model for that and call Stored procedure with a model. But I could not create a model with looping. Is there any way to create a model with that idea.
Or do you have any idea to get result set without model from stored procedure?
I'm using oData library so it would be great if it can do that.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Http.OData;
namespace WebService.Controllers.OData.Common
{
public class CallSPWithoutColumnDefinitionController : ODataController
{
private SitContextTuborg db = new SitContextTuborg();
[EnableQuery]
//[SITAuthorize]
public IQueryable<CallSPWithoutColumnDefinitionModel> GetCallSPWithoutColumnDefinition()
{
Dictionary<string, string> parameterValues = new Dictionary<string, string>();
List<CallSPWithoutColumnDefinitionModel> ReturnValues = new List<CallSPWithoutColumnDefinitionModel>();
parameterValues.Add("STR_CO_NAME", "Pages");
var Results = db.ExecuteProcedureWithAuth<CallSPWithoutColumnDefinitionModel>("[Load-Co-Confıg.R01]", this.Request.GetClientIp(), parameterValues).ToList();
foreach (CallSPWithoutColumnDefinitionModel item in Results)
{
ReturnValues.Add(new CallSPWithoutColumnDefinitionModel()
{
LNG_ID = item.LNG_ID,
STR_COLL_NAME = item.STR_COLL_NAME,
STR_TYPE = item.STR_TYPE
});
}
return ReturnValues.AsQueryable();
}
public class tmpCallSPWithoutColumnDefinitionModel
{
//we need to create model with a for loop with Returnvalues' coll names above
}
}
}
private static Tuple<string, object[]> PrepareArguments(string storedProcedure, object parameters)
{
var parameterNames = new List<string>();
var parameterParameters = new List<object>();
if (parameters != null)
{
foreach (PropertyInfo propertyInfo in parameters.GetType().GetProperties())
{
string name = string.Format("#{0}", propertyInfo.Name);
object value = propertyInfo.GetValue(parameters, null);
parameterNames.Add(name);
parameterParameters.Add(new SqlParameter(name, value ?? DBNull.Value));
}
}
if (parameterNames.Count > 0)
storedProcedure = string.Format("{0} {1}", storedProcedure, string.Join(", ", parameterNames));
return new Tuple<string, object[]>(storedProcedure, parameterParameters.ToArray());
}
From: http://code-clarity.blogspot.in/2012/02/entity-framework-code-first-easy-way-to.html
You could use an ExpandoObject from System.Dynamic.
Here's a working example:
DataTable tbl = new DataTable();
tbl.Columns.Add(new DataColumn("hello", typeof(int)));
tbl.Columns.Add(new DataColumn("world", typeof(string)));
DataRow newRow = tbl.NewRow();
newRow["hello"] = 1;
newRow["world"] = "boobies";
tbl.Rows.Add(newRow);
foreach (DataRow row in tbl.Rows)
{
var expando = new ExpandoObject() as IDictionary<string, Object>;
foreach (DataColumn col in tbl.Columns)
{
expando.Add(col.ColumnName, row[col.ColumnName]);
}
}
What's important here is that when we call Add on that ExpandoObject, it's actually going to add those values as PROPERTIES on that object. Pretty nifty!
actually I think something is misunderstood. I have ReturnValues as you see in code as return value.. I need to send it to a model class below and I need to
CREATE new MODEL structure ;
something like
[Column("COLUMN1")] public string COLUMN1{ get; set; }
[Column("COLUMN2")] public string COLUMN2{ get; set; }
So I could not send it to class and create a model like above..
I have a grid, and I'm setting the DataSource to a List<IListItem>. What I want is to have the list bind to the underlying type, and disply those properties, rather than the properties defined in IListItem. So:
public interface IListItem
{
string Id;
string Name;
}
public class User : IListItem
{
string Id { get; set; };
string Name { get; set; };
string UserSpecificField { get; set; };
}
public class Location : IListItem
{
string Id { get; set; };
string Name { get; set; };
string LocationSpecificField { get; set; };
}
How do I bind to a grid so that if my List<IListItem> contains users I will see the user-specific field? Edit: Note that any given list I want to bind to the Datagrid will be comprised of a single underlying type.
Data-binding to lists follows the following strategy:
does the data-source implement IListSource? if so, goto 2 with the result of GetList()
does the data-source implement IList? if not, throw an error; list expected
does the data-source implement ITypedList? if so use this for metadata (exit)
does the data-source have a non-object indexer, public Foo this[int index] (for some Foo)? if so, use typeof(Foo) for metadata
is there anything in the list? if so, use the first item (list[0]) for metadata
no metadata available
List<IListItem> falls into "4" above, since it has a typed indexer of type IListItem - and so it will get the metadata via TypeDescriptor.GetProperties(typeof(IListItem)).
So now, you have three options:
write a TypeDescriptionProvider that returns the properties for IListItem - I'm not sure this is feasible since you can't possibly know what the concrete type is given just IListItem
use the correctly typed list (List<User> etc) - simply as a simple way of getting an IList with a non-object indexer
write an ITypedList wrapper (lots of work)
use something like ArrayList (i.e. no public non-object indexer) - very hacky!
My preference is for using the correct type of List<>... here's an AutoCast method that does this for you without having to know the types (with sample usage);
Note that this only works for homogeneous data (i.e. all the objects are the same), and it requires at least one object in the list to infer the type...
// infers the correct list type from the contents
static IList AutoCast(this IList list) {
if (list == null) throw new ArgumentNullException("list");
if (list.Count == 0) throw new InvalidOperationException(
"Cannot AutoCast an empty list");
Type type = list[0].GetType();
IList result = (IList) Activator.CreateInstance(typeof(List<>)
.MakeGenericType(type), list.Count);
foreach (object obj in list) result.Add(obj);
return result;
}
// usage
[STAThread]
static void Main() {
Application.EnableVisualStyles();
List<IListItem> data = new List<IListItem> {
new User { Id = "1", Name = "abc", UserSpecificField = "def"},
new User { Id = "2", Name = "ghi", UserSpecificField = "jkl"},
};
ShowData(data, "Before change - no UserSpecifiedField");
ShowData(data.AutoCast(), "After change - has UserSpecifiedField");
}
static void ShowData(object dataSource, string caption) {
Application.Run(new Form {
Text = caption,
Controls = {
new DataGridView {
Dock = DockStyle.Fill,
DataSource = dataSource,
AllowUserToAddRows = false,
AllowUserToDeleteRows = false
}
}
});
}
As long as you know for sure that the members of the List<IListItem> are all going to be of the same derived type, then here's how to do it, with the "Works on my machine" seal of approval.
First, download BindingListView, which will let you bind generic lists to your DataGridViews.
For this example, I just made a simple form with a DataGridView and randomly either called code to load a list of Users or Locations in Form1_Load().
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
using Equin.ApplicationFramework;
namespace DGVTest
{
public interface IListItem
{
string Id { get; }
string Name { get; }
}
public class User : IListItem
{
public string UserSpecificField { get; set; }
public string Id { get; set; }
public string Name { get; set; }
}
public class Location : IListItem
{
public string LocationSpecificField { get; set; }
public string Id { get; set; }
public string Name { get; set; }
}
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void InitColumns(bool useUsers)
{
if (dataGridView1.ColumnCount > 0)
{
return;
}
DataGridViewCellStyle gridViewCellStyle = new DataGridViewCellStyle();
DataGridViewTextBoxColumn IDColumn = new DataGridViewTextBoxColumn();
DataGridViewTextBoxColumn NameColumn = new DataGridViewTextBoxColumn();
DataGridViewTextBoxColumn DerivedSpecificColumn = new DataGridViewTextBoxColumn();
IDColumn.DataPropertyName = "ID";
IDColumn.HeaderText = "ID";
IDColumn.Name = "IDColumn";
NameColumn.DataPropertyName = "Name";
NameColumn.HeaderText = "Name";
NameColumn.Name = "NameColumn";
DerivedSpecificColumn.DataPropertyName = useUsers ? "UserSpecificField" : "LocationSpecificField";
DerivedSpecificColumn.HeaderText = "Derived Specific";
DerivedSpecificColumn.Name = "DerivedSpecificColumn";
dataGridView1.Columns.AddRange(
new DataGridViewColumn[]
{
IDColumn,
NameColumn,
DerivedSpecificColumn
});
gridViewCellStyle.SelectionBackColor = Color.LightGray;
gridViewCellStyle.SelectionForeColor = Color.Black;
dataGridView1.RowsDefaultCellStyle = gridViewCellStyle;
}
public static void BindGenericList<T>(DataGridView gridView, List<T> list)
{
gridView.DataSource = new BindingListView<T>(list);
}
private void Form1_Load(object sender, EventArgs e)
{
dataGridView1.AutoGenerateColumns = false;
Random rand = new Random();
bool useUsers = rand.Next(0, 2) == 0;
InitColumns(useUsers);
if(useUsers)
{
TestUsers();
}
else
{
TestLocations();
}
}
private void TestUsers()
{
List<IListItem> items =
new List<IListItem>
{
new User {Id = "1", Name = "User1", UserSpecificField = "Test User 1"},
new User {Id = "2", Name = "User2", UserSpecificField = "Test User 2"},
new User {Id = "3", Name = "User3", UserSpecificField = "Test User 3"},
new User {Id = "4", Name = "User4", UserSpecificField = "Test User 4"}
};
BindGenericList(dataGridView1, items.ConvertAll(item => (User)item));
}
private void TestLocations()
{
List<IListItem> items =
new List<IListItem>
{
new Location {Id = "1", Name = "Location1", LocationSpecificField = "Test Location 1"},
new Location {Id = "2", Name = "Location2", LocationSpecificField = "Test Location 2"},
new Location {Id = "3", Name = "Location3", LocationSpecificField = "Test Location 3"},
new Location {Id = "4", Name = "Location4", LocationSpecificField = "Test Location 4"}
};
BindGenericList(dataGridView1, items.ConvertAll(item => (Location)item));
}
}
}
The important lines of code are these:
DerivedSpecificColumn.DataPropertyName = useUsers ? "UserSpecificField" : "LocationSpecificField"; // obviously need to bind to the derived field
public static void BindGenericList<T>(DataGridView gridView, List<T> list)
{
gridView.DataSource = new BindingListView<T>(list);
}
dataGridView1.AutoGenerateColumns = false; // Be specific about which columns to show
and the most important are these:
BindGenericList(dataGridView1, items.ConvertAll(item => (User)item));
BindGenericList(dataGridView1, items.ConvertAll(item => (Location)item));
If all items in the list are known to be of the certain derived type, just call ConvertAll to cast them to that type.
You'll need to use a Grid template column for this. Inside the template field you'll need to check what the type of the object is and then get the correct property - I recommend creating a method in your code-behind which takes care of this. Thus:
<asp:TemplateField HeaderText="PolymorphicField">
<ItemTemplate>
<%#GetUserSpecificProperty(Container.DataItem)%>
</ItemTemplate>
</asp:TemplateField>
In your code-behind:
protected string GetUserSpecificProperty(IListItem obj) {
if (obj is User) {
return ((User) obj).UserSpecificField
} else if (obj is Location) {
return ((Location obj).LocationSpecificField;
} else {
return "";
}
}
I tried projections, and I tried using Convert.ChangeType to get a list of the underlying type, but the DataGrid wouldn't display the fields. I finally settled on creating static methods in each type to return the headers, instance methods to return the display fields (as a list of string) and put them together into a DataTable, and then bind to that. Reasonably clean, and it maintains the separation I wanted between the data types and the display.
Here's the code I use to create the table:
DataTable GetConflictTable()
{
Type type = _conflictEnumerator.Current[0].GetType();
List<string> headers = null;
foreach (var mi in type.GetMethods(BindingFlags.Static | BindingFlags.Public))
{
if (mi.Name == "GetHeaders")
{
headers = mi.Invoke(null, null) as List<string>;
break;
}
}
var table = new DataTable();
if (headers != null)
{
foreach (var h in headers)
{
table.Columns.Add(h);
}
foreach (var c in _conflictEnumerator.Current)
{
table.Rows.Add(c.GetFieldsForDisplay());
}
}
return table;
}
When you use autogeneratecolumns it doesnt automatically do this for you?
My suggestion would be to dynamically create the columns in the grid for the extra properties and create either a function in IListItem that gives a list of available columns - or use object inspection to identify the columns available for the type.
The GUI would then be much more generic, and you would not have as much UI control over the extra columns - but they would be dynamic.
Non-checked/compiled 'psuedo code';
public interface IListItem
{
IList<string> ExtraProperties;
... your old code.
}
public class User : IListItem
{
.. your old code
public IList<string> ExtraProperties { return new List { "UserSpecificField" } }
}
and in form loading
foreach(string columnName in firstListItem.ExtraProperties)
{
dataGridView.Columns.Add(new DataGridViewTextBoxColumn { DataPropertyName = columnName, HeaderText = columnName );
}
If you are willing to use a ListView based solution, the data-bindable version ObjectListView will let you do this. It reads the exposed properties of the DataSource and creates columns to show each property. You can combine it with BindingListView.
It also looks nicer than a grid :)