I am trying to modify parts of some pre-existing code to return a Page and use Pageable. However I am at a loss as to how to approach this. From the little I found I need to have "Limit" and "Offset", but am using SQL Server which doesn't recognize the syntax.
public List<TotalForAllDTO> findAll() {
String query = queryProps.getProperty("findAll");
return jdbcTemplate.query(query, new Object[]{}, new TotalForAllDTOMapper());
Any guidance would be very helpful.
Related
I am fairly new to C# and Dapper. I am trying to write a generic Insert Data method for my project. I come from a Delphi environment so I am still finding my way around C#.
Dapper seems fairly straight forward to use but I am experiencing some challenges. I have tried every which way to get the syntax right with the following code but have been unsuccessful.
Issues seem to be around the T (I still quite don't understand what T is) and all the combinations I have tried don't work.
public async Task<int> InsertData<T>(T list)
{
string connectionString = _config.GetConnectionString(ConnectionStringName);
using (IDbConnection connection = new SqlConnection(connectionString))
{
return await connection.InsertAsync<int>(list);
}
}
The following code does work, so where am I going wrong?
public async Task SaveData<T>(string sql, T parameters)
{
string connectionString = _config.GetConnectionString(ConnectionStringName);
using (IDbConnection connection = new SqlConnection(connectionString))
{
await connection.ExecuteAsync(sql, parameters);
}
}
Your second code (await connection.ExecuteAsync(sql, parameters);) works because you are simply executing your hand written SQL statement. The method ExecuteAsync belongs to Dapper; NOT Dapper.Contrib. The generic T is used for parameters, not for the object you are trying to insert.
With your first code (return await connection.InsertAsync<int>(list);), you are actually using Dapper.Contrib; you are not writing the SQL statement by hand. Dapper.Contrib generates it for you.
Your following code seems the problem:
return await connection.InsertAsync<int>(list);
You are passing generic parameter <int> to the method which does not make sense.
I have not tested this but I hope changing that line to below one should work:
return await connection.InsertAsync<T>(list);
Also, you have to make sure the generic type T is class by adding where T : class to it.
Following generic method should serve your purpose; you need to convert it to async to match with your current code:
public void InsertData<T>(T entity) where T : class
{
string connectionString = ....;
using(IDbConnection connection = new SqlConnection(connectionString))
{
long result = connection.Insert<T>(entity);
}
}
I did not understood few other parts in your code. Say InsertData<T>(T list). What is list? Is it as single object or list of objects? If it is list of objects, List<T> list makes more sense. If it is single object, better you rename list to actual object name, say T customer/entity/poco etc.
I am new to BreezeJS and would like to know if there are any examples on how to use Breeze with an SQL Stored Procedure?
We have some pretty complex queries and want to be able to call them via an SP. Also, how can we tell Breeze that a column returned from a SP is the Key? We don't want to use Views, because we need to pass variables to the SP query each time we call it.
Thanks.
bob
Ok, the basic idea would be to use Breeze's EntityQuery.withParameters method to pass parameters to a server side method that calls your stored proc and returns an IEnumerable. ( i.e. the result of the stored proc).
If you want to treat this result as collection of Breeze entities then you will either need to shape the results into an existing entity type that Breeze knows about from Metadata OR manually create and add a new EntityType on the client that matches the shape that you want to return.
You may want to look at the EntityQuery.toType method to force breeze to convert your returned data into a specific EntityType or you might alternately want to use a "jsonResultsAdapter" to do the same thing.
Any data that is returned from a query and is converted into an Breeze EntityType is automatically wrapped according the "modelLibrary" in use, i.e. Knockout, Angular, Backbone etc.
If breeze is not able to construct entities out of the returned data then it will still be returned but without any special processing to wrap the result.
Hope this helps!
A sample to access Sql Stored Procedures from Breeze; the store procedure (GoStoCde) has been imported by EF.
Breeze Controller :
[HttpGet]
public object GetCdes(long jprod, int jqte, long jorder)
{
//output params
var owrk = new System.Data.Objects.ObjectParameter("wkres", typeof(string));
owrk.Value = "";
var oeror = new System.Data.Objects.ObjectParameter("ceror", typeof(int));
oeror.Value = 0;
//invoke stored procedure
var envocde = _contextProvider.Context.GoStoCde(jprod, jqte, jorder, owrk, oeror);
//stored procedure results
var cdeResult = new {
dwork = owrk.Value,
deror = oeror.Value,
};
return new { cdeResult };
}
Datacontext :
function reqLnecde(iprod, iqte, iorder, vxeror) {
logger.log("commande en cours...");
var query = new EntityQuery.from("GetCdes")
.withParameters({ jprod: iprod, jqte: iqte, jorder: iorder });
return manager
.executeQuery(query)
.then(querySucceeded)
.fail(cqueryFailed);
function querySucceeded(data) {
//stored procedure results
vxeror(data.results[0]);
//stored procedure object member value
keror = vxeror().cdeResult.deror;
if (keror === 0) {
logger.log("commande done");
} else {
logger.log("article absent");
}
}
function queryFailed(data) {
logger.log("commande failed"); //server errors
}
}
If you prefer to return entity in lieu of object, code consequently and its must also work.
Hope this helps!
Not really an answer here, just a few thoughts.
I think that the ability to return arbitrarily shaped data (read viewmodel) through the use of a stored procedure using withParameters would be an excellent way to inegerate with something like dapper.net. Upon resubmission of said viewmodel you could use the overloads to reconstruct actual entities out of your viewmodel and save changes. The only problem I have though is that one would need a way to easily and automaticaly rerun the sproc and send the data back to the client...
I would like to know if this makes sense to anyone else and/or if anyone has done it already.
For this sort of scenario I would think that you would need to disable the tracking features provided by breeze and/or write a smart enough data service that can handle the viewmodels in such a way that the javascript on the client knows when adding/removing/updating parts x,y,z of viewmodel a that you create objects jx, jy, jz (j for javascript) and submit them back and save as you go (reverse idea of what was mentioned above in a way)
Thoughts?
Is there any way to define the SQL conversion component for additional functions to Linq2Entities.
For example:
myQuery.Where(entity => entity.Contains('foo', SearchFlags.All))
Ideally I am looking for something that doesn't require editing and building a new version the EntityFramework.dll directly. Is there any way to allow extension methods to entity framework that can support SQL generation.
So far I have a template which would represent the method I need to replace for LINQ to Entities:
public static bool Contains(this object source, string searchTerms, SearchFlags flags)
{
return true;
}
Of course this causes the error:
LINQ to Entities does not recognize the method 'Boolean
CONTAINS(System.Object, System.String, SearchFlags)' method, and this method
cannot be translated into a store expression.
To be clear, I don't want to do:
myQuery.AsEnumerable().Where(entity => entity.Contains('foo', SearchFlags.All))
Because I want to be able to execute code in SQL space and not return all the entities manually.
I also cannot use the .ToString() of the IQueryable and execute it manually because I need Entity Framework to populate the objects from several .Include joins.
I don't understand your Q clearly. However if your problem is that you can't use your own methods or other linq to objects method, just use .AsEnumerable() and do your other jobs through linq to objects, not L2E:
myQuery.AsEnumerable().Where(entity => entity.Contains('foo', SearchFlags.All))
And if you need to use your myQuery several times somewhere else, first load it to memory, then use it as many as you want:
var myQuery = from e in context.myEntities
select d;
myQuery.Load();
// ...
var myOtherQuery = from d in context.myEntities.Local
select d;
// Now any L2O method is supported...
I ended up doing the following (which works but is very far from perfect):
All my entities inherit from an IEntity which defines long Id { get; set; }
I then added a redundant restriction
context.myEntities.Where(entity => entity.Id != 0) this is
redundant since the identity starts at 1, but Linq2Entities doesn't
know that.
I then call .ToString() on the IQueryable after I have done all
my other queries, since it is of type DBQuery<Entity> it returns
the SQL Command Text, I do a simple replace with my query restriction.
In order to get all the .Include(...) to work I actually execute
two different sql commands. There is no other more pretty way to tap into this because of query execution plan caching causes issues otherwise (even when disabled).
As a result my code looks like this:
public IQueryable<IEntity> MyNewFunction(IQueryable<IEntity> myQueryable, string queryRestriction)
{
string rawSQL = myQueryable.Select(entity => entity.Id).ToString().Replace("[Extent1].Id <> 0", queryRestriction);
List<long> ids = // now execute rawSQL, get the list of ids;
return myQuerable.Where(entity => ids.Contains(entity.Id));
}
In short, other than manually executing the SQL or running a similar SQL command and appending the restriction using the existing commands the only way to write your own methods to Linq-to-Entities is to manually alter and build your own EntityFramework.dll from the EF6 source.
I've a legacy database that all sites have, it describes specific content in a number of catagory/subcatagory/child item format. Until now, adding/editing the content is either manual work in the tables OR raw sql Windows Forms tool (I built when I started out in the job!).
I would like Entity Framework style drag, drop, bind and run coding ability with WPF 4.5 and .net 4.5.
I hesitate to use NHibernate as EF5 is very simple to get going with, I understand Nhibernate is more work (albeit a faster ORM). Are there alternatives that work well? I'm trying to avoid too much manual setup, if possible. The editor isn't a mandatory project and I can't justify lots of extra work on it - but it would make my job easier for the next 2 years if a nice version of it was put together.
All the argument against Access I know really well :) - swapping this isn't an option for at least a year.
Having searched the StackOverflow site, I don't see too many questions asking for this, but apologies if I've missed a good one!
Update: I think I should refine my question slightly as really what I needed to get at what code generation so that I don't need to hand build all the classes for the Access database. From what I can see, Dapper's work is around efficiency but is distinct from generating code. Coming from a entity framework mindset, I can see where I've conjoined the tasks somewhat in my thinking :). So apart from boil my own - does anyone know a good code gen for use with Access. This I can marry to Dapper :).
You can't use Entity Framework, because it doesn't work with Access databases.
It's possible to use NHibernate with MS Access, although NH doesn't support Access out of the box.
You need NHibernate.JetDriver from NHContrib and here are example settings for the NH config file.
If I recall it correctly, NH Contrib needs to be compiled against the exact NH version you're using, so you probably need to download the source code and compile it by yourself.
As an alternative, you can use one of the many micro-ORMs, for example Stack Overflow's own Dapper.
Dapper is DB agnostic, so it can connect to everything including Access. Quote from the official site:
Will dapper work with my db provider?
Dapper has no DB specific implementation details, it works across all .net ado providers
including sqlite, sqlce, firebird, oracle, MySQL and SQL Server
The disadvantage is that because Dapper is DB agnostic, you have to implement some advanved stuff yourself, like paging.
EDIT:
IMO Dapper is in the "fairly easy to run quickly catagory".
Take a look at this:
(complete demo project here)
using System;
using System.Data.OleDb;
using Dapper;
namespace DapperExample
{
class Program
{
static void Main(string[] args)
{
using (var con = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=test.mdb"))
{
var list = con.Query<Product>("select * from products");
Console.WriteLine("map to a strongly typed list:");
foreach (var item in list)
{
Console.WriteLine(item.ProductNumber + " : " + item.Description);
}
Console.WriteLine();
var list2 = con.Query("select * from products");
Console.WriteLine("map to a list of dynamic objects:");
foreach (var item in list2)
{
Console.WriteLine(item.ProductNumber + " : " + item.Description);
}
Console.ReadLine();
}
}
}
public class Product
{
public string ProductNumber { get; set; }
public string Description { get; set; }
}
}
There are two different queries in this example code.
The first one maps to a strongly typed list, e.g. the result is an IEnumerable<Product>. Of course it needs a Product class that it can map to.
The second query returns an IEnumerable<Dynamic> (>= .NET 4.0) which means that the properties are evaluated on the fly and you don't need to define a class before, but the disadvantage is that you lose type safety (and IntelliSense).
My personal opinion is that the missing type safety is a deal breaker for me (I prefer the first query syntax), but maybe this is something for you.
Hate to resurrect an old thread but I recently did a WPF project using PetaPoco, a micro-ORM, with MS Access so I thought I'd share my implementation.
To add MS Access support to PetaPoco, you just need to add a couple of bits of code:
First add an AccessDatabaseType class. All of the DataBaseType classes are at the end of the PetaPoco.cs file. Just add the new class after SqlServerDatabaseType.
class AccessDatabaseType : DatabaseType
{
public override object ExecuteInsert(Database db, IDbCommand cmd, string PrimaryKeyName)
{
db.ExecuteNonQueryHelper(cmd);
return db.ExecuteScalar<object>("SELECT ###IDENTITY AS NewID;");
}
}
Next, modify PetaPoco.Internal.DatabaseType.Resolve() to support the AccessDatabaseType. (This code assumes you are using the Jet OLEDB provider)
public static DatabaseType Resolve(string TypeName, string ProviderName)
{
//...
if (ProviderName.IndexOf("Oledb", StringComparison.InvariantCultureIgnoreCase) >= 0)
return Singleton<AccessDatabaseType>.Instance;
// Assume SQL Server
return Singleton<SqlServerDatabaseType>.Instance;
}
Finally, to instantiate PetaPoco use this:
Db = New PetaPoco.Database("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\db.mdb", "System.Data.Oledb")
Limitations:
PetaPoco assumes your primary keys are autonumber/identity fields. If you have a PK that's not an autonumber or you have a composite PK, you'll need to implement your own insert & save logic.
I didn't need paging in my application so I didn't implement it.
We are using
Jet Entity Framework Provider. That way we can easily port to another database later.
It does not have all the limitations mentioned above and works great.
Tortuga Chain fully supports Access.
https://docevaad.github.io/Chain/Introduction.htm
This should be simple, but I haven't found a way yet...
I have a legacy database with name fields that are stored as CHAR(50). When this is bound to a TextBox with a Max Length of 50, you cannot insert.
How can I make the EF trim these values or at least map to RTrim(Column)?
I've tried using value converters, but the round trip causes issues with back spacing and spaces getting deleted between words.
Note that I only want to trim some fields, not all.
We are using SQL Server 2000 as the database. Soon to move to SQL 2008.
Thanks!
Entity framework is able to map only to table directly. You can also map to view or custom DB query but in such case your entity will became readonly unless you also map Insert, Delete and Update operations to stored procedures.
I think the problem you describes is related to ANSI PADDING behavior. It can be turned on but:
It is not recommended. In future version of SQL server it will be considered as error.
Must be configured before you create a column
You must handle trimming in the application. You can for example modify T4 template (if you use them) to trim string properties. Not sure how it works with WPF but you probably can inherit text box and override Text property to trim values.
Another way is handling ObjectMaterialized event on ObjectContext and manually trimming text properties but it can slow down your execution of your queries.
There's no way to do this with EF and SQL Server that I have found. I solved it with an extension method on IEnumerable<T> that calls TrimEnd() on each string property:
public static IEnumerable<TEntity> Trim<TEntity>(this IEnumerable<TEntity> collection)
{
Type type = typeof(TEntity);
IEnumerable<PropertyDescriptor> properties = TypeDescriptor.GetProperties(type).Cast<PropertyDescriptor>()
.Where(p => p.PropertyType == typeof(string));
foreach (TEntity entity in collection)
{
foreach (PropertyDescriptor property in properties)
{
string value = (string) property.GetValue(entity);
if (!String.IsNullOrEmpty(value))
{
value = value.TrimEnd();
property.SetValue(entity, value);
}
}
}
return collection;
}
Just make sure you call it after EF has retrieved the entities from the database. For example, after ToList():
public IEnumerable<Country> FetchCountries()
{
return _context.Set<Country>().ToList().Trim();
}
Have a look at the available attributes for your Database Connection String. I had a similar issue with Sybase Advantage database and solved with it's TrimTrailingSpaces attribute. Your database may support something similar.
Data Source=\\serverx\volumex\path\db.add;User ID=user;Password=pass;ServerType=REMOTE;TrimTrailingSpaces=TRUE;
http://www.connectionstrings.com/