I'm trying to select all the rows out of a database using entity framework for manipulation before they're sent to the form
var ptx = [modelname].[tablename]();
ptx.[tablename].Select(????)
what goes in the ????
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9 Answers
I used the entitydatasource and it provide everything I needed for what I wanted to do.
_repository.[tablename].ToList();
3 Comments
Capt. Rochefort
I wanted to return all rows of a table without a stupid .Where(row => row.Id > 0) and knew it was something simple. Perfect. Thanks.
Andrew
What is _repository?
Rocky Raccoon
@Andrew
_repository is the name of the OP's class for the Entity Framework data context.Entity Framework has one beautiful thing for it, like :
var users = context.Users;
This will select all rows in Table User, then you can use your .ToList() etc.
For newbies to Entity Framework, it is like :
PortalEntities context = new PortalEntities();
var users = context.Users;
This will select all rows in Table User
5 Comments
Callum Linington
I would say that a name like
PortalEntities is fairly miss-leading, usually it would be SomethingContext and you would name the variable context. This because of the naming conventions entity framework have used, so usually you will inherit from the DbContext. My statements usually are using (var context = this.contextFactory.Create()) {}
Irf
@CallumLinington :By default, in VS 2015, if you create a context by adding
ADO.NET Entity Data Model Database First Approach by selecting (EF Designer from Database), it will name your Model as Model(n) and your context class name will be DatabaseNameEntities, which is of course being inherited from DBContext.Callum Linington
Fair enough, but I would still say that's missleading, or at least il-named!
Irf
@CallumLinington Not a fire a debate, but Microsoft's example here, everywhere it seems to use AdventureWorksEntities.
Callum Linington
Yeah, I see they do. I still would never change my mind :) .
How about:
using (ModelName context = new ModelName())
{
var ptx = (from r in context.TableName select r);
}
ModelName is the class auto-generated by the designer, which inherits from ObjectContext.
answered Jun 5, 2012 at 15:33
Mike Christensen
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2 Comments
Callum Linington
doesnt work! it ask for what model.table is (obviously i put in the entity stuff)
muttley91
Note that you can specify such things as
select r.PropertyName to get actual parts of the entry, should you want specific "columns".You can use this code to select all rows :
C# :
var allStudents = [modelname].[tablename].Select(x => x).ToList();
Comments
You can simply iterate through the DbSet context.tablename
foreach(var row in context.tablename)
Console.WriteLn(row.field);
or to evaluate immediately into your own list
var allRows = context.tablename.ToList();
Comments
If it's under a async method then use ToListAsync()
public async Task<List<DocumentTypes>> GetAllDocumentTypes()
{
var documentTypes = await _context.DocumentTypes.ToListAsync();
return documentTypes;
}
Comments
Old post I know, but using Select(x => x) can be useful to split the EF Core (or even just Linq) expression up into a query builder.
This is handy for adding dynamic conditions.
For example:
public async Task<User> GetUser(Guid userId, string userGroup, bool noTracking = false)
{
IQueryable<User> queryable = _context.Users.Select(x => x);
if(!string.IsNullOrEmpty(userGroup))
queryable = queryable.Where(x => x.UserGroup == userGroup);
if(noTracking)
queryable = queryable.AsNoTracking();
return await queryable.FirstOrDefaultAsync(x => x.userId == userId);
}
Comments
Here is a few ways to do it (Just assume I'm using Dependency Injection for the DbConext)
public class Example
{
private readonly DbContext Context;
public Example(DbContext context)
{
Context = context;
}
public DbSetSampleOne[] DbSamples { get; set; }
public void ExampleMethod DoSomething()
{
// Example 1: This will select everything from the entity you want to select
DbSamples = Context.DbSetSampleOne.ToArray();
// Example 2: If you want to apply some filtering use the following example
DbSamples = Context.DbSetSampleOne.ToArray().Where(p => p.Field.Equals("some filter"))
}
Comments
You can use:
ptx.[tablename].Select( o => true)
5 Comments
Callum Linington
so what object do you put it into?
Glaxalg
It will select all objects. "true" - is a condition of object selection.
Matt Wilko
Can you add more explanation, links to reference material etc
avenmore
(-1) This selects "true" for each row.
shashwat
It should be
ptx.[tablename].Where(o => true)