EmilianoMusso.EFCoreExtensions.DbToInMemory 1.1.0-alpha.1

EmilianoMusso.EFCoreExtensions.DbToInMemory

A library to easy load persisted data from database to InMemory

Usage:

Let's suppose we have a Sql Server instance named MyInstance, and a database named MyDatabase. The database contains tables, two of them named MyTableType and AnotherTableType. We need to use already persisted data for our integration tests, without tampering the real data, but using it.

EF Core allow us to specify a memory instanced data context using UseInMemoryDatabase method, which allow us to replicate our model in an in-memory structure. This method supports initial seeding through migrations, but this extension has the purpose to make easier the in-memory data seeding.

Please consider the following snippet:

var optionsBuilder = new DbContextOptionsBuilder<MyDbContext>()
    .UseInMemoryDatabase("TEST");

var context = new MyDbContext(optionsBuilder.Options);

var connectionString = @"Server=.\MyInstance;Database=MyDatabase;Trusted_Connection=True;";
var toInMem = new DatabaseToInMemory(context, connectionString);

toInMem.LoadTable<MyTableType>()
       .LoadTable<AnotherTableType>(5)
       .PersistToMemory();

Here, we have declared an in-memory database modeled on an already existant DbContext. Then, having instantiated our context, we can simply initialize a new object of DatabaseToInMemory type.

That class must be initialized by passing a DbContext and a connection string to a physical database. Afterwards, we can use the LoadTable<T> method, where <T> is one of the types present in our context to indicate the DbSets representing each table. That method accepts a parameter to specify a number of record to be loaded (10 by default).

Unless otherwise stated in the DatabaseToInMemory constructor, data will be picked randomly from each table. At the end of load operations, which can be concatenated, we can call PersistToMemory or PersistToMemoryAsync - which are two wrappers for SaveChanges and SaveChangesAsync - to persist our data in the in-memory database.

v1.1.0-alpha.1

From this version on, it is possible to specify an expression to select entities from tables. The LINQ expression will be translated to SQL syntax. A sample of this process can be seen in the original repository, on the test project, and can be resumed like the following.

var linqExpression = "x => x.Property01.Contains(\"A\") AndAlso x.Property02 == 1";
var expectedClause = "WHERE Property01 LIKE '%A%' AND Property02 = 1";

var result = LinqFuncToSqlLangHelper.GetSQLWhereClause(linqExpression);
result.Should().Be(expectedClause);

LoadTable<T> method could thus be implemented with a selector, like this:

toInMem.LoadTable<MyTableType>()
       .LoadTable<AnotherTableType>(x => x.Property01 > 100, topRecords: 5)
       .LoadTable<ThirdType>(x => x.StringProp.StartsWith("E") && x.TestProperty != 10, topRecords: 5)
       .PersistToMemory();

Further translation possibilities will come in future versions.