linq2db.EntityFrameworkCore

linq2db.EntityFrameworkCore

LINQ To DB

Build status

Feeds

• NuGet
• Azure Artifacts (feed)

Unique features

• Fast Eager Loading (incomparable faster on massive

  Include

  query)
• Global Query Filters optimization
• Better SQL optimization
• Use CTE in LINQ queries
• MERGE statement support
• Table hints
• Full Window functions support
• Fast BulkCopy of millions records
• Native SQL operations for updating, deleting, inserting records via LINQ query
• Temporary Tables support
• Cross Database/Linked Server queries.
• Full Text Search extensions
• A lot of extensions to cover ANSI SQL # How to use

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

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

DbSet

ToLinqToDBTable()

For

ITable

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

LINQ To DB

// 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

ToLinqToDB()

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

ToListAsyncLinqToDB()

SumAsyncLinqToDB()

EF Core

LINQ To DB

EF

ToListAsyncEF()

SumAsyncEF()

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.

Why should I want to use it?

There are many reasons. Some of them:

• you want to use advanced SQL functionality, not supported or poorly supported by EntityFrameworkCore like BulkCopy support, SQL MERGE operations, convinient DML (Insert/Delete/Update) operations and many-many-many other features LINQ To DB provides, but you need change tracking functionality that EntityFramework provides.
• you want to migrate to LINQ To DB, but need to do it step-by-step.
• just because LINQ To DB is cool.

Current status

Below is a list of providers, that should work right now:

• SQL Server
• MySQL (including Devart and Pomelo providers)
• PostgreSQL (Both npgsql and Devart providers)
• SQLite (including Devart provider)
• Firebird
• DB2 LUW
• Oracle
• SQL Server CE

Know limitations

• No Lazy loading
• No way to work with in-memory database

Help! It doesn't work!

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.