linq2db.EntityFrameworkCore
is an integration of LINQ To DB
with existing EntityFrameworkCore projects. It was inspired by this issue in EF.Core repository.
Include
query)In your code you need to initialize integration using following call:
LinqToDBForEFTools.Initialize();
After that you can just call DbContext and IQueryable extension methods, provided by LINQ To DB
.
You can also register additional options (like interceptors) for LinqToDB during EF context registration, here is an example:
var optionsBuilder = new DbContextOptionsBuilder<MyDbContext>();
optionsBuilder.UseSqlite();
optionsBuilder.UseLinqToDB(builder =>
{
// add custom command interceptor
builder.AddInterceptor(new MyCommandInterceptor());
// add additional mappings
builder.AddMappingSchema(myCustomMappings);
// configure SQL Server dialect explicitly
builder.AddCustomOptions(o => o.UseSqlServer(SqlServerVersion.v2022));
});
There are many extensions for CRUD Operations missing in vanilla EF (watch our video):
// fast insert big recordsets
ctx.BulkCopy(new BulkCopyOptions {...}, items);
// query for retrieving products that do not have duplicates by Name
var query =
from p in ctx.Products
from op in ctx.Products.LeftJoin(op => op.ProductID != p.ProductID && op.Name == p.Name)
where Sql.ToNullable(op.ProductID) == null
select p;
// insert these records into the same or another table
query.Insert(ctx.Products.ToLinqToDBTable(), s => new Product { Name = s.Name ... });
// update these records by changing name based on previous value
query.Update(prev => new Product { Name = "U_" + prev.Name ... });
// delete records that matched by query
query.Delete();
Some extensions require LINQ To DB ITable<T>
interface, which could be acquired from DbSet<T>
using ToLinqToDBTable()
extension method.
For ITable<T>
interface LINQ To DB provides several extensions that may be useful for complex databases and custom queries:
table = table.TableName("NewTableName"); // change table name in query
table = table.DatabaseName("OtherDatabase"); // change database name, useful for cross database queries.
table = table.OwnerName("OtherOwner"); // change owner.
// inserting into other existing table Products2
query.Insert(ctx.Products.ToLinqToDBTable().TableName("Products2"), s => new Product { Name = s.Name ... });
It is not required to work directly with LINQ To DB
DataConnection
class but there are several ways to do that. LINQ To DB
will try to reuse your configuration and select appropriate data provider:
// uing DbContext
using (var dc = ctx.CreateLinqToDBConnection())
{
// linq queries using linq2db extensions
}
// using DbContextOptions
using (var dc = options.CreateLinqToDBConnection())
{
// linq queries using linq2db extensions
}
You can use all LINQ To DB
extension functions in your EF linq queries. Just ensure you have called ToLinqToDB()
function before materializing objects for synchronous methods.
Since EF Core have defined it's own asynchronous methods, we have to duplicate them to resolve naming collisions.
Async methods have the same name but with LinqToDB
suffix. E.g. ToListAsyncLinqToDB()
, SumAsyncLinqToDB()
, ect. The same methods are added whe you need EF Core
query processing but there is collision with LINQ To DB
and they have extensions with EF
suffix - ToListAsyncEF()
, SumAsyncEF()
, ect.
using (var ctx = CreateAdventureWorksContext())
{
var productsWithModelCount =
from p in ctx.Products
select new
{
// Window Function
Count = Sql.Ext.Count().Over().PartitionBy(p.ProductModelID).ToValue(),
Product = p
};
var neededRecords =
from p in productsWithModelCount
where p.Count.Between(2, 4) // LINQ To DB extension
select new
{
p.Product.Name,
p.Product.Color,
p.Product.Size,
// retrieving value from column dynamically
PhotoFileName = Sql.Property<string>(p.Product, "ThumbnailPhotoFileName")
};
// ensure we have replaced EF context
var items1 = neededRecords.ToLinqToDB().ToArray();
// async version
var items2 = await neededRecords.ToLinqToDB().ToArrayAsync();
// and simple bonus - how to generate SQL
var sql = neededRecords.ToLinqToDB().ToString();
}
Also check existing tests in test project for some examples.
There are many reasons. Some of them:
Below is a list of providers, that should work right now:
If you encounter any issue with this library, first check issues to see if it was already reported and if not, feel free to report new issue.