Small, powerful SQL-based ORM for .NET
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MonkeyOrm is a small, powerful SQL-based ORM for .NET.


Only MySql is supported at the moment. A nuget is available, just run the following command in the Package Manager Console:

Install-Package MonkeyOrm.MySql

Save anything


connection.Save("Users", new User { Name = "Anne", Age = 31 });

Anonymous objects:

connection.Save("Users", new { Name = "John", Age = 26 });

Hashes: IDictionary<>, IDictionary, ExpandoObject or NameValueCollection:

connection.Save("Users", new Dictionary<string, object>
                                    { "Name", "Fred" },
                                    { "Age", 22 }

Get back the auto generated serial id if any:

int pabloId;
connection.Save("Users", new User { Name = "Pablo", Age = 49 }, out pabloId);
What the heck is connection?

MonkeyOrm Api consists mainly of extension methods, just like the Save method in the snippets above. Several types are extended: connection can be an IDbConnection, an IDbTransaction, any function in your code returning a new connection Func<IDbConnection>, or the MonkeyOrm defined interface IConnectionFactory.


connection.Update("Users", new { CanBuyAlchohol = true }, "Age >= @age", new { age = 21 });

Save or Update

connection.SaveOrUpdate("Users", new User { Name = "Anne", Age = 32 });

Aka Upsert. Attempts to save first. If the insertion violates a key or unicity constraint, an update is performed instead.


connection.Delete("Users", "Name=@name", new { name = "Sauron" });


By default, ExpandoObjects are used to map the data read from the database and are returned as dynamic to client code.

If strongly typed objects are preferred to dynamic, MonkeyOrm can do the mapping for you to any provided user type. To do that, all the Read methods listed here have Read<T> overloads.

Read just one item

var joe = connection.ReadOne("Select * From Users Where Name = @name", new { name = "Joe" });

Reads only the first element, if any, from the result set. You can also read computed data:

var stats = connection.ReadOne("Select Max(Age) As Max, Min(Age) As Min From Users");
Console.WriteLine("Max {0} - Min {1}", stats.Max, stats.Min);

Read'em All

var users = connection.ReadAll("Select * From Users Where Age > @age", new { age = 30 });

Bulk fetches the whole result set in memory as a list.

Stream Read

Instead of bulk fetching query results in memory, they are wrapped in an enumerable for lazy evaluation. Items are loaded from the databse when the returned IEnumerable is actually enumerated, one at a time.

Here is an example where results are streamed from the database to a file on disk:

var users = connection.ReadStream("Select * From Users");

using(var file = new StreamWriter("result.txt"))
foreach (var user in users)
    file.WriteLine("{0} - {1}", user.Name, user.Age);

Two Bonus Points: (1) the result enumerable can be enumerated multiple times if data needs to be re-streamed from the database (the query will be executed again), (2) Linq queries can be used on the result as for any enumerable, no restrictions.

ReadStream has also an overload that —instead of returning the result as an enumerable— takes a function that it calls for each result item until it returns false. The snippet above would be equivalent to:

using(var file = new StreamWriter("result.txt"))
connection.ReadStream("Select * From Users", user => 
    file.WriteLine("{0} - {1}", user.Name, user.Age);
    return true;


int spockId = connection.InTransaction(autocommit: true).Do(t =>
    int id;
    t.Save("Users", new { Name = "Spock", Age = 55 }, out id);
    t.Save("Profiles", new { UserId = id, Bio = "Federation Ambassador" });
    return id;

The transaction block can be a function or an action. The return value, if any, is returned back to client code. The transaction can be manually committed at any point by invoking t.Commit(). Setting the autocommit parameter to true will insert a call to Commit() after the transaction block.

The transaction isolation level can be specified using the isolation parameter:

connection.InTransaction(true, IsolationLevel.Serializable).Do(t =>
    var james = t.ReadOne("Select * From Users Where Name=@name", new { name = "James" });
    t.Update("Users", new { Age = james.Age + 15 }, "Id=@Id", new { james.Id });

Batch insertion

Batch insertion enables insertion of enumerable data sets; whether this data set is held in memory or streamed from any other source (file, database, network, computed on the fly etc.).

connection.SaveBatch("Users", new[]
        new User { Name = "Monica", Age = 34 },
        new User { Name = "Fred", Age = 58 },
        // ...

By default, one object at a time is read from the provided enumerable and inserted in the database. In order to tune memory usage vs network round-trips more elements can be loaded and inserted at once. This is controlled by the chunkSize parameter.

In the following snippet, 100 objects are loaded and inserted at once —in the same query— from the provided enumerable to the database.

connection.SaveBatch("Users", LoadDataFromRemoteSource(), 100);

Batch insertion can also be wrapped in a transaction

connection.InTransaction().SaveBatch("Users", users);

Object Slicing

In some contexts, the object (or hash) to be saved in the database needs to be filtered in order to exclude some of its properties. This can be for security reasons: the object has been automatically mapped from user input —by a model binder or a similar mechanism— and thus needs to be checked against the set of authorized properties. Not properly filtering user input is a security vulnerability; the github site was hacked due to a similar issue (if you want to read more about this).

MonkeyOrm can slice the input object when calling Save or Update by applying either a black list or a white list filter on object properties.

connection.Save("Users", user, blacklist: new[] { "IsAdmin" });

This will prevent a hacker form forging user input that would force IsAdmin column to true.

connection.Update("Users", user, "Id=@id", new { id }, whitelist: new[] { "Name", "Age" });

Only allows Name and Ageto be updated, nothing else.

Interceptors and Blobbing

Interceptors are functions you can set in order to control how data is processed by MonkeyOrm. One interesting interceptor is the UnknownValueType interceptor. It is called when the data to be inserted in a database column does not map directly to a database native type. Consider the following example:

connection.Save("Users", new { Name="Joe", Age=67, Profile=new ProfileData { /* ... */ });

The property Profile holds an instance of POCO type ProfileData. This type can't be directly inserted into the column Profile of the Users table as it is.

In this situation, MonkeyOrm calls the UnknownValueType callback in order the give client code a chance to "intercept" the non-trivial type and transform it to something the database can handle. A typical example would be to blob (serialize) the ProfileData instance. Here is an example of a xml blobber interceptor:

MonkeyOrm.Settings.Interceptors.UnknownValueType = o =>
    var writer = new StringWriter();
    new XmlSerializer(o.GetType()).Serialize(writer, o);
    return writer.ToString();

Custom non Query Commands

Execute runs any valid SQL code:

connection.Execute("Truncate Table Users");

It can also run commands with parameters:

    "Insert Into Users (Name, Age) Values (@Name, @Age)",
    new { Name = "Philip", Age = 55 });

Related Projects


Copyright 2012-2013 Sinbadsoft.

Licensed under the Apache License, Version 2.0.