Micro-ORM Introduction - Don't overcomplicate

Don't overcomplicateIntroduction to Micro ORM

Ivan Korneliuk@korneliukhttp://korneliuk.blogspot.com/31337

Kiev ALT.NET

What wrong with ORM?

• Inadequate abstraction

• Inefficiency

• Complexity

• Requires overcomplicated infrastructure around

Micro ORM

• Massive by Rob Connery

• Simple.Data by Mark Rendle

• Peta Poco by Top Ten Software

• Dapper by Sam Saffron

dapper-dot-netSimple SQL object mapper for ADO.NET

• Created by StackOverflow guys

• Single file

• Read oriented

• Ultra fast - performance is a key feature

• Pure SQL 

dapper-dot-netMain concepts

Enrich IDbCommand with extension methods for querying and executing sql commands.

Can map query results to list of POCOs or dynamics.

dapper-dot-netQuerying POCOs

public class Dog { public int? Age { get; set; } public Guid Id { get; set; } public string Name { get; set; } public float? Weight { get; set; } public int IgnoredProperty { get { return 1; } } }

var guid = Guid.NewGuid(); var dog = connection.Query<Dog>( "select Age = @Age, Id = @Id", new { Age = (int?)null, Id = guid });

dog.Count().IsEqualTo(1);dog.First().Age.IsNull();dog.First().Id.IsEqualTo(guid);

dapper-dot-netAdvanced features

List support - automatically parameterize query by passing IEnumerable

connection.Query<int>( @"select * from (select 1 as Id union select 2 union select 3) as X where Id in @Ids", new { Ids = new int[] { 1, 2, 3 });

select * from (select 1 as Id union select 2 union all select 3) as X where Id in (@Ids1, @Ids2, @Ids3) // @Ids1 = 1 , @Ids2 = 2 , @Ids2 = 3

dapper-dot-netAdvanced features

Multi mapping - maps single row to several objects

var sql = @"select * from #Posts p left join #Users u on u.Id = p.OwnerId Order by p.Id";var data = connection.Query<Post, User, Post>( sql, (post, user) => { post.Owner = user; return post;});

var post = data.First();

post.Content.IsEqualTo("Sams Post1"); post.Id.IsEqualTo(1); post.Owner.Name.IsEqualTo("Sam"); post.Owner.Id.IsEqualTo(99);

dapper-dot-netAdvanced features

Multiple results - processes multiple result grids with a single query.

var sql = @“ select * from Customers where CustomerId = @id select * from Orders where CustomerId = @id select * from Returns where CustomerId = @id";

using (var multi = conn.QueryMultiple(sql, new {id=Id})) { var customer = multi.Read<Customer>().Single(); var orders = multi.Read<Order>().ToList(); var returns = multi.Read<Return>().ToList(); ... }

• Buffered and unbuffered readers (fetching results)

• Executing Stored Procedures

• Dapper.Contrib - Handling C(r)UD operationso Marking classes with attributeso Change tracking

• Queries caching

dapper-dot-netAdvanced features

MassiveSingle file database lover

"I wanted to stay as close to the "metal" as I possibly could. This (to me) meant that I didn't want to worry about Types, Tracking Containers, Contexts and so on. What I did want to do is describe my table - and this is the only type I have (which, ironically, is a Dynamic type)"

Single file with less than 700 lines of code (including comments).

MassiveInitializing table// Create a class that wraps a tablepublic class Products:DynamicModel { public Products():base("northwind", "products","productid") {}}

// or instantiate it inlinevar tbl = new DynamicModel( "northwind", tableName:"Products", primaryKeyField:"ProductID");

MassiveQuerying

var table = new Products();var products = table.All( columns: "ProductName as Name", where: "WHERE categoryID=@0", args: 4);

var products = table.Find(CategoryID:4,columns:"ProductName")

// Running ad-hoc queries as needed:var result = tbl.Query("SELECT * FROM Categories");var result = tbl.Fetch("SELECT * FROM Categories");

// Pagingvar result = tbl.Paged(where: "UnitPrice > 20", currentPage:2, pageSize: 20);

MassiveUpdating

var table = new Products();var poopy = new {ProductName = "Chicken Fingers"};table.Update(poopy, 12);

// Works for a form on a web pagetable.Update(poopy, Request.Form);

// Insertvar table = new Categories();var newID = table.Insert(new {CategoryName = "Buck Fify Stuff", Description = "Things I like"});

// Batch updatesvar table = new Products();var drinks = table.All("WHERE CategoryID = 8");// what we get back here is an IEnumerable<ExpandoObject>foreach(var item in drinks){ item.CategoryID = 12;}table.Save(drinks);

Massive

public class Productions :DynamicModel { public Productions(): base("MyConnectionString","Productions","ID") {} public override void Validate(dynamic item) { ValidatesPresenceOf("Title"); ValidatesNumericalityOf(item.Price); ValidateIsCurrency(item.Price); if (item.Price <= 0) Errors.Add("Price can't be negative"); }}

public class Customers: DynamicModel { public Customers():base("MyConnectionString","Customers","ID") {}

//Add the person to Highrise CRM when they're added to the system... public override void Inserted(dynamic item) { //send them to Highrise var svc = new HighRiseApi(); svc.AddPerson(...); }}

Changes notification

Validation

PetaPocoTiny ORM to use with non-dynamic POCO objects

• Inspired by Massive but works with strongly typed POCOs

• Also supports dynamic Expandos

• T4 template for generating classes from database schema

• Marking classes with attributes

• The query language is SQL

• Helper methods for Insert/Delete/Update/Save and IsNew

• Hooks for logging exceptions, installing value converters and mapping columns to properties without attributes

• Works even if you stuck with .NET 3.5

PetaPoco

Code samples

Simple.Dataan ORM without O, the R or the M

"A lightweight, dynamic data access component for .NET"

Simple.Data

• Microsoft.Data done right

• Really simple

• Protects from SQL injection

• Convention based and LINQ like syntax

• Master-detail relations without SELECT N+1

• Easy testing with mock database

Simple.DataSyntax overview

dynamic db = Database.Open();User user = db.Users.FindByUserName("bob"); // Method name formuser = db.Users.FindBy(UserName: "bob"); // Named parameter form

@p0 = 'bob'SELECT * FROM Users WHERE UserName = @p0

IEnumerable<dynamic> customers = db.Customers .FindAll(db.Customers.CustomerName == "Arthur") .OrderByCustomerName() .Distinct();

@p1 = 'Arthur'select distinct dbo.customers.customerid, dbo.customers.customer_namefrom [dbo].[customers] where [dbo].[customers].[customer_name] = @p1 order by [customer_name]

FindAllBy

FindBy

Simple.DataSyntax overview

var q = db.Employees.Query() .Join(db.Department, Id: db.Employees.DepartmentId) .Select(db.Employees.Name, db.Department.Name.As("Department"));

var q = db.Employees .Find(db.Employees.DepartmentId == db.Department.Id) .Select(db.Employees.Name, db.Department.Name.As("Department"));

select [dbo].[employee].[name], [dbo].[department].[name] as [Department] from [dbo].[employee]join [dbo].[department] on ([dbo].[department].[id] = [dbo].[employee].[departmentid])

Explicit join

Natural join (dynamic form)

Simple.DataSyntax overview - Insert

var user = db.Users.Insert(Name: "Steve", Age: 50);

@p0 = 'Steve'@p1 = 50insert into [dbo].[Users] ([Name],[Age]) values (@p0,@p1)

var user = new User { Name = "Steve", Age = 50 };db.Users.Insert(user);

By object

Named parameters

Generated SQL:

Insert, Update and Delete methods return a row or rowSet of data that has just been modified.

Insert and Update can be used in two forms, Named parameters and by object. The object can be a POCO or a dynamic.

Simple.DataSyntax overview - Update

db.Users.UpdateById(Id: 1, Name: "Steve", Age: 50);

@p0 = 1, @p1 = 'Steve', @p2 = 50update [dbo].[Users] set [Name] = @p1, [Age] = @p2 where [dbo].[Users].[Id] = @p3

dynamic record = new SimpleRecord();record.Id = 1;record.Name = "Steve";record.Age = 50;

db.Users.UpdateById(record); // Method name formdb.Users.Update(record); // By Primary Key

By object (can be POCO or dynamic)

Named parameters

Generated SQL:

Simple.DataSyntax overview - UpdateAll

db.Users.UpdateAll(Name: "Steve");

@p0 = 'Steve'update [dbo].[Users] set [Name] = @p

Named parameters

db.Users.UpdateAll(Name: "Steve", Condition: db.Users.Age > 30);

db.Users.UpdateAll(db.Users.Age > 30, Name: "Steve");

With expression

@p0 = 'Steve'@p1 = 30update [dbo].[Users] set [Name] = @p0 where [dbo].[Users].[Age] > @p1

Simple.DataSyntax overview - Delete

db.Users.Delete(Id: 1);

Named parameters

db.Users.DeleteById(Id: 1);

db.Users.DeleteAll(db.Users.Age > 42 && db.Users.Name.Like("J%"));

Method name form

db.Users.DeleteAll();

With expression

With no Where clause

Simple.DataPersonal experience

Used in two production systems.

First one is CQRS based and Simple.Data is used to actualize “Read Model” there.

Within the second one, Simple.Data is used to store normalized data which we receive from third party in XML form.

In both systems Simple.Data is used for integration tests.

It just amazing how simpler design can be when you don’t need data classes just to map them to database tables.

Simple.Data

Real code examples

TL;DRWhat I liked in Micro ORMs

Usually leads to better performance. Though, that was not a key feature for me.

Write less, do more – instead of writing infrastructural code (Session management, Repositories, Specifications, Mappings etc.) you concentrated on getting things done…. things which business needs, not technical issues dictated by our infrastructure.

With less features in Micro ORMs you are forced to design things simpler – simpler object hierarchies, simpler database schema. And you are forced to apply good patterns. Separating Reads and Writes is a good example.

That all leads to a better design.

ReferencesGeneral•“ORM is an anti-pattern” article – http://seldo.com/weblog/2011/06/15/orm_is_an_antipattern •Micro ORM Samples – https://github.com/ijrussell/MicroORM

•InfoQ. Micro ORMs with Sam Saffron and Rob Conery – http://www.infoq.com/articles/ORM-Saffron-Conery•Hanselminutes Podcast 262 - The Rise of the Micro-ORM with Sam Saffron and Rob Conery http://www.hanselman.com/blog/HanselminutesPodcast262TheRiseOfTheMicroORMWithSamSaffronAndRobConery.aspx

Dapper-dot-net•Home – http://code.google.com/p/dapper-dot-net/ (with performance comparison)•“How I learned to stop worrying and write my own ORM” –http://samsaffron.com/archive/2011/03/30/How+I+learned+to+stop+worrying+and+write+my+own+ORM•“A day in the life of a slow page at Stack Overflow” - http://samsaffron.com/archive/2011/05/02/A+day+in+the+life+of+a+slow+page+at+Stack+Overflow

Massive•Home – https://github.com/robconery/massive•Rob Conery blog - http://wekeroad.com/

ReferencesPetaPoco•Source – https://github.com/toptensoftware/petapoco•Documentation – http://www.toptensoftware.com/petapoco/

Simple.Data•Source – https://github.com/markrendle/Simple.Data•Documentation – http://simplefx.org/simpledata/docs/•Mark Rendle blog - http://blog.markrendle.net/•HERDING CODE 106: MARK RENDLE ON SIMPLE.DATA (podcast) – http://herdingcode.com/?p=305•.Net Rocks! podcast “Mark Rendle Has Some Simple.Data” – http://www.dotnetrocks.com/default.aspx?showNum=683

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