See Gurux for an overview.
Join the Gurux Community or follow @Gurux for project updates.
Gurux ORM is an open-source Object Relational Mapping (ORM) component for C#, part of the Gurux Device Framework.
Its goal is to provide a fast and easy-to-use ORM that works across multiple database engines.
- Unified ORM interface for multiple databases
- Automatic table creation and relation traversal
- See generated SQL in debug mode (hover on the argument)
- Lambda-expression query support
- Attribute-driven schema mapping
- Supports
1:1,1:N, andN:Nrelationships
| Attribute | Description |
|---|---|
DataMember |
Marks a field to be stored in the database. |
AutoIncrement |
Increases on insert; value is written back to the object. |
ForeignKey |
Defines a foreign key relation. |
Relation |
Declares a relation between tables. |
Alias |
SQL alias for fields/tables. |
UseEnumStringValue |
Save enums as strings (default is integer). |
UseEpochTimeFormat |
Store dates as UNIX epoch. |
StringLength(int max) |
Validates and limits string length in the schema. |
IsRequired |
Field must have a value (NOT NULL). |
Gurux ORM supports:
- 1:1 — One-to-One
- 1:N — One-to-Many
- N:N — Many-to-Many
All ORM classes must implement IUnique<T>, ensuring a unique ID for each object.
This makes lookups faster and relations easier to manage.
GXCountry maintains a list of its companies and cascades deletes.
[DataContract]
class GXCountry : IUnique<int>
{
[DataMember(Name = "ID"), AutoIncrement]
public int Id { get; set; }
[DataMember(Name = "CountryName"), IsRequired, StringLength(100)]
public string Name { get; set; }
[DataMember]
[ForeignKey(OnDelete = ForeignKeyDelete.Cascade)]
public List<GXCompany> Companies { get; set; }
}
[DataContract]
class GXCompany : IUnique<long>
{
[AutoIncrement, DataMember]
public long Id { get; set; }
[DataMember, IsRequired, StringLength(150)]
public string Name { get; set; }
// Navigation to Country; FK column is auto-managed (e.g., CountryID)
[DataMember(Name = "CountryID"), ForeignKey]
public GXCountry Country { get; set; }
}Usage Example:
GXCountry finland = new GXCountry { Name = "Finland" };
GXCompany gurux = new GXCompany { Name = "Gurux Ltd", Country = finland };
GXCompany sample = new GXCompany { Name = "Sample Co", Country = finland };
finland.Companies = new List<GXCompany> { gurux, sample };
// Create Country and all related tables in one go (including Company)
Connection.CreateTable<GXCountry>(true, false);
Connection.Insert(GXInsertArgs.Insert(finland));GXUser holds a direct reference to GXCompany (no CompanyId).
[DataContract]
class GXCompany : IUnique<long>
{
[AutoIncrement, DataMember]
public long Id { get; set; }
[DataMember, IsRequired, StringLength(150)]
public string Name { get; set; }
[DataMember, ForeignKey(OnDelete = ForeignKeyDelete.Cascade)]
public GXUser[] Users { get; set; }
}
[DataContract]
class GXUser : IUnique<int>
{
[AutoIncrement, DataMember]
public int Id { get; set; }
[DataMember, IsRequired, StringLength(120)]
public string Name { get; set; }
[DataMember, ForeignKey(OnDelete = ForeignKeyDelete.Cascade)]
public GXCompany Company { get; set; }
}Usage Example:
GXCompany company = new GXCompany { Name = "Gurux Ltd" };
GXUser u1 = new GXUser { Name = "Alice", Company = company };
GXUser u2 = new GXUser { Name = "Bob", Company = company };
company.Users = new[] { u1, u2 };
// Create Company and all related tables (Users) in one go
Connection.CreateTable<GXCompany>(true, false);
Connection.Insert(GXInsertArgs.Insert(company));[DataContract]
class GXUser : IUnique<int>
{
[AutoIncrement, DataMember]
public int Id { get; set; }
[DataMember, IsRequired, StringLength(120)]
public string Name { get; set; }
[DataMember, ForeignKey(typeof(GXUserGroup), typeof(GXUserToUserGroup))]
public GXUserGroup[] Groups { get; set; }
[DataMember, ForeignKey(OnDelete = ForeignKeyDelete.Cascade)]
public GXCompany Company { get; set; }
}
[DataContract]
class GXUserGroup : IUnique<int>
{
[AutoIncrement, DataMember]
public int Id { get; set; }
[DataMember, IsRequired, StringLength(120)]
public string Name { get; set; }
[DataMember, ForeignKey(typeof(GXUser), typeof(GXUserToUserGroup))]
public GXUser[] Users { get; set; }
}
[DataContract]
class GXUserToUserGroup
{
[DataMember, ForeignKey(typeof(GXUser), OnDelete = ForeignKeyDelete.Cascade)]
public int UserId { get; set; }
[DataMember, ForeignKey(typeof(GXUserGroup), OnDelete = ForeignKeyDelete.Cascade)]
public int GroupId { get; set; }
}Usage Example:
GXUserGroup adminGroup = new GXUserGroup { Name = "Admin" };
GXUserGroup devGroup = new GXUserGroup { Name = "Developers" };
GXCompany gurux = new GXCompany { Name = "Gurux Ltd" };
GXUser user = new GXUser
{
Name = "Charlie",
Company = gurux,
Groups = new[] { adminGroup, devGroup }
};
// Create UserGroup and all related tables (bridge + users + company) in one go
Connection.CreateTable<GXUserGroup>(true, false);
Connection.Insert(GXInsertArgs.Insert(user));Create all related tables with a single call, do CRUD, and prefer GXDeleteArgs.Delete(obj) when you have the instance.
using Gurux.ORM;
using System.Collections.Generic;
using System.Data.SQLite;
class Program
{
static void Main()
{
// 1. Connect to SQLite (you can also use MySQL, SQL Server, etc.)
var sqlite = new SQLiteConnection("Data Source=:memory:");
var Connection = new GXDbConnection(sqlite, null);
// 2. Create all related tables starting from GXCountry
Connection.CreateTable<GXCountry>(true, false);
// 3. Insert data
GXCountry finland = new GXCountry { Name = "Finland" };
GXCompany gurux = new GXCompany { Name = "Gurux Ltd", Country = finland };
GXCompany sample = new GXCompany { Name = "Sample Co", Country = finland };
finland.Companies = new List<GXCompany> { gurux, sample };
Connection.Insert(GXInsertArgs.Insert(finland));
GXUser john = new GXUser { Name = "John", Company = gurux };
GXUser jane = new GXUser { Name = "Jane", Company = gurux };
Connection.Insert(GXInsertArgs.Insert(john));
Connection.Insert(GXInsertArgs.Insert(jane));
GXUserGroup devs = new GXUserGroup { Name = "Developers" };
john.Groups = new[] { devs };
Connection.Insert(GXInsertArgs.Insert(john));
// 4. Query data
GXSelectArgs selectUsers = GXSelectArgs.SelectAll<GXUser>();
List<GXUser> users = Connection.Select<GXUser>(selectUsers);
// 5. Update data
john.Name = "John Updated";
Connection.Update(GXUpdateArgs.Update(john, q => q.Name));
// 6. Delete data (preferred when you have the instance)
Connection.Delete(GXDeleteArgs.Delete(john));
}
}GXSelectArgs arg = GXSelectArgs.Select<GXUser>(s => "*");
arg.Columns.Add<GXUserGroup>();
arg.Joins.AddInnerJoin<GXUser, GXUserToUserGroup>(j => j.Id, j => j.UserId);
arg.Joins.AddInnerJoin<GXUserToUserGroup, GXUserGroup>(j => j.GroupId, j => j.Id);
var list = Connection.Select<GXUser>(arg);Only users in the "Developers" group, ascending by user name:
GXSelectArgs arg = GXSelectArgs.Select<GXUser>(s => "*");
arg.Columns.Add<GXUserGroup>();
arg.Joins.AddInnerJoin<GXUser, GXUserToUserGroup>(j => j.Id, j => j.UserId);
arg.Joins.AddInnerJoin<GXUserToUserGroup, GXUserGroup>(j => j.GroupId, j => j.Id);
// Filter: group name equals "Developers"
arg.Where.And<GXUserGroup>(g => g.Name == "Developers");
// Sort: users by Name (ascending)
arg.OrderBy.Add<GXUser>(u => u.Name, true);
var developers = Connection.Select<GXUser>(arg);Alternative (portable) approach using a subquery:
// Subquery: find group IDs with name 'Developers'
var groupsSub = GXSelectArgs.Select<GXUserGroup>(g => g.Id, g => g.Name == "Developers");
// Users whose Groups contain one of the subquery results
var usersInDevs = GXSelectArgs.Select<GXUser>(
s => "*",
u => GXSql.In(u => u.Groups, groupsSub)
);
// Optional sort
usersInDevs.OrderBy.Add<GXUser>(u => u.Name, true);
var developers2 = Connection.Select<GXUser>(usersInDevs);GXSelectArgs arg = GXSelectArgs.Select<GXUser>(s => "*");
arg.Where.And<GXUser>(c => c.Name.StartsWith("Cha"));
var filtered = Connection.Select<GXUser>(arg);GXSelectArgs arg = GXSelectArgs.Select<GXUser>(s => "*");
arg.OrderBy.Add<GXUser>(c => c.Name);
var sorted = Connection.Select<GXUser>(arg);You can also combine:
GXSelectArgs arg = GXSelectArgs.Select<GXUser>(s => "*"); arg.Where.And<GXUser>(c => c.Name.StartsWith("Cha")); arg.OrderBy.Add<GXUser>(c => c.Name); var result = Connection.Select<GXUser>(arg);
GXSelectArgs arg = GXSelectArgs.SelectAll<GXCountry>();
arg.Columns.Add<GXCompany>();
arg.Joins.AddInnerJoin<GXCountry, GXCompany>(c => c.Id, c => c.Country);
List<GXCountry> countries = Connection.Select<GXCountry>(arg);Use Exclude<T>() to omit specific fields from queries and updates. Great for skipping heavy columns on read and avoiding server-managed columns on update.
Exclude in Select
// Select all fields for GXUser, but exclude heavy/sensitive ones
GXSelectArgs args = GXSelectArgs.SelectAll<GXUser>(it);
args.Exclude<GXUser>(q => new
{
// Fields to exclude from the query result:
// e.g., q.PasswordHash, q.ProfileImageBlob, q.InternalNote
});
var users = Connection.Select<GXUser>(args);Exclude in Update
// Update from an instance 'it' while skipping server-managed or immutable fields
GXUpdateArgs args = GXUpdateArgs.Update(it);
args.Exclude<GXUser>(q => new
{
// Fields to exclude from updates:
// e.g., q.Id, q.CreatedAt, q.Company, q.PasswordHash
});
Connection.Update(args);Practical example
// READ: don't fetch large binary data or secrets
GXSelectArgs s = GXSelectArgs.SelectAll<GXUser>(it);
s.Exclude<GXUser>(q => new { q.PasswordHash, q.AvatarBlob });
var list = Connection.Select<GXUser>(s);
// UPDATE: avoid changing keys or audit fields
GXUpdateArgs u = GXUpdateArgs.Update(it);
u.Exclude<GXUser>(q => new { q.Id, q.Company, q.CreatedAt, q.UpdatedAt });
Connection.Update(u);user.Name = "UpdatedName";
Connection.Update(GXUpdateArgs.Update(user, q => q.Name));// Preferred when you have the instance:
Connection.Delete(GXDeleteArgs.Delete(user));
// If only the ID is known:
Connection.Delete(GXDeleteArgs.DeleteById<GXUser>(5));GXSelectArgs sub = GXSelectArgs.Select<GXUser>(q => q.Id, q => q.Id > 100);
GXSelectArgs arg = GXSelectArgs.Select<GXUserGroup>(null, q => q.Id > GXSql.In(q => q.Users, sub));For examples and tests, check:
Gurux.Service_Simple_UnitTests directory
Need help?
Ask your questions on the Gurux Forum.
