LINQ to Entities query to DataTable
There is one important thing here, you are casting your Linq query to (IEnumerable<DataRow>
) when you are selecting the vendedor
, so I assume that vendedor is an instance of Vendedor
, so your query will return an IEnumerable<Vendedor>
That should solve your problem, but also, can you try using the generated DataTable as the DataSource for your DataGridView? It would be something like this:
var query = (from vendedor in db.Vendedores.AsEnumerable()
where vendedor.codigo == Convert.ToInt32(textBoxPesquisa.Text)
select vendedor);
var dt = query.CopyToDataTable<Vendedor>();
this.dataGridViewProcura.DataSource = dt;
Hope I can help!
EDIT
As a side (and very personal) note, you could try using lambdas on your select, they look prettier :)
var pesquisa = Convert.ToInt32(textBoxPesquisa.Text);
var query = db.Vendedores.Where(vendedor => vendedor.codigo == pesquisa);
var dt = query.CopyToDataTable<Vendedor>();
this.dataGridViewProcura.DataSource = dt;
A lot cleaner, don't you think?
EDIT 2 I've just realized what you said on CopyToDataTable being for DataRow only, so last (admittedly not so clean) solution would be to mimic the logic on the helper?
public DataTable CopyGenericToDataTable<T>(this IEnumerable<T> items)
{
var properties = typeof(T).GetProperties();
var result = new DataTable();
//Build the columns
foreach ( var prop in properties ) {
result.Columns.Add(prop.Name, prop.PropertyType);
}
//Fill the DataTable
foreach( var item in items ){
var row = result.NewRow();
foreach ( var prop in properties ) {
var itemValue = prop.GetValue(item, new object[] {});
row[prop.Name] = itemValue;
}
result.Rows.Add(row);
}
return result;
}
Now, things to consider:
- This solution will not work with complex properties
- Customizing the resulting table might be a bit tricky
While this might solve the issue, I don't think this is a very good approach, but it could be the start of a decent idea :)
I hope I can help this time!
![Zignd](https://i.stack.imgur.com/9L8cQ.jpg?s=256&g=1)
Zignd
Updated on August 11, 2020Comments
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Zignd almost 4 years
I need to store the data returned from this LINQ to Entities query (below) into a DataTable so that I can use it as data source to a DataGridView, how can I do that?
In this case I'm using LINQ to Entities to query against an Entity Framework conceptual model, so
db
is a class that inherits fromSystem.Data.Entity.DbContext
.using (TccContext db = new TccContext()) { var query = from vendedor in db.Vendedores.AsEnumerable() where vendedor.codigo == Convert.ToInt32(textBoxPesquisa.Text) select vendedor; // I'd like to do something like DataTable dt = query; }
I've tried to do this (below), but it throws an exception during execution [1].
using (TccContext db = new TccContext()) { IEnumerable<DataRow> query = (IEnumerable<DataRow>)(from vendedor in db.Vendedores.AsEnumerable() where vendedor.codigo == Convert.ToInt32(textBoxPesquisa.Text) select vendedor); using (DataTable dt = query.CopyToDataTable<DataRow>()) { this.dataGridViewProcura.Rows.Add( dt.Rows[0][0], // Código dt.Rows[0][1], // Nome dt.Rows[0][2]); // Venda Mensal } }
[1]: Exception:
InvalidCastException
Unable to cast object of type 'WhereEnumerableIterator`1[Projeto_TCC.Models.Vendedor]' to type 'System.Collections.Generic.IEnumerable`1[System.Data.DataRow]'.
Thanks in advance
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Zignd almost 11 yearsThe method CopyToDataTable will not be available in the
query
if I use it like that. Please note that I'm using Entity Framework. -
David Conde almost 11 yearsI made a typo on the last source, and as the edit says, the CopyToDataTable method should work there. btw - Did the answer helped at all?
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Zignd almost 11 yearsAs you can see in the same link, to gain access to the CopyToDataTable method the T type in the IEnumerable<T> must be of type DataRow, but as instead you used the class that represents the database table Vendedor I end up not having access to those extension methods that includes the CopyToDataTable.
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Palindrom about 9 yearsIt is not valid solution for converting to data table
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DaniDev almost 8 years@David Conde I spend a little time trying to implement your initial solution, as I believed I had stumbled upon a quick fix that I had overlooked. Unfortunately, I arrived at the same dead end as zigrid. I was a little frustrating to then read the comments and realize that this is not a valid option.
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DaniDev almost 8 yearsI have been implementing a couple of other Object "shredder" to DataTable solutions such as the one you suggest in your EDIT 2(@David Conde ), but I have discovered that can be either problematic for complex types (as mentioned) especially EntityTypes with foreign keys or very costly or both. I think that in many cases it is simply best to abandon the Entity types and query the DB directly which easily converts to a DataTable