LiteOrm在线文档

Entity Mapping and Data Sources

Entity classes are the mapping foundation between LiteOrm and database tables. This article introduces core rules for entity definition, table-column mapping, multiple data sources, and sharding parameters.

Basic Entity Structure

[Table("Users")]
public class User
{
    [Column("Id", IsPrimaryKey = true, IsIdentity = true)]
    public int Id { get; set; }

    [Column("UserName")]
    public string? UserName { get; set; }

    [Column("Age")]
    public int Age { get; set; }

    [Column("DeptId")]
    public int? DeptId { get; set; }

    [Column("CreateTime")]
    public DateTime CreateTime { get; set; }
}

ObjectBase is an optional base class. You can use LiteOrm perfectly fine without inheriting from it.

`[Table]` Attribute

[Table("Users")]
[Table("Logs_{0}", DataSource = "LogDB")]

Parameter	Description
`Name`	Database table name, supports placeholder for sharding.
`DataSource`	Specifies the data source for the current entity.

`[Column]` Attribute

[Column("Id", IsPrimaryKey = true, IsIdentity = true)]
[Column("Profile", DataType = typeof(UserProfile))]

Parameter	Description
`Name`	Database column name.
`IsPrimaryKey`	Whether it is a primary key.
`IsIdentity`	Whether it is an identity column.
`DataType`	Serialization type, used for complex object storage.

`[PropertyOrder]` Attribute

Controls the ordering of entity properties in database operations (e.g., table creation, SQL column list generation).

[Table("Users")]
public class User
{
    [PropertyOrder(1)]
    [Column("Id", IsPrimaryKey = true, IsIdentity = true)]
    public int Id { get; set; }

    [PropertyOrder(2)]
    [Column("UserName")]
    public string? UserName { get; set; }

    [PropertyOrder(After = nameof(DeptId))]
    [Column("Age")]
    public int Age { get; set; }

    [PropertyOrder(0)]
    [Column("DeptId")]
    public int? DeptId { get; set; }
}

Parameter	Description
`Order`	Sort priority. Lower values come first. Default is 0. Within the same topological level, properties with smaller Order values are placed first.
`After`	Specifies a property name; indicates the current property should be placed after it.
`Before`	Specifies a property name; indicates the current property should be placed before it.

Sorting Rule: Properties are first sorted by Before/After topological dependencies, then within the same level by Order value ascending, and finally by original declaration order. An InvalidOperationException is thrown when circular dependencies are detected.

Multi-DataSource Mapping

If there are multiple data sources in the project, you can explicitly mark them on the entity:

[Table("Orders", DataSource = "OrderDb")]
public class Order
{
}

This way, all default read/write operations for this entity will use the OrderDb data source.

Sharding Parameters and `IArged`

When the table name contains placeholders, you can provide dynamic sharding parameters via IArged:

[Table("Logs_{0}")]
public class Log : IArged
{
    [Column("CreateTime")]
    public DateTime CreateTime { get; set; }

    string[] IArged.TableArgs => new[] { CreateTime.ToString("yyyyMM") };
}

For more details, see Sharding and TableArgs.

Modeling Recommendations

Keep entities simple; avoid cramming too much business logic into entities.
Metadata like primary keys, identity columns, and data sources should be clearly defined at the model layer from the start.
For fields that need association queries, prefer using view models; don’t pollute basic entities.
When dealing with cross-database or legacy database compatibility, confirm the corresponding dialect behavior in advance.

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LiteOrm在线文档

Entity Mapping and Data Sources

Basic Entity Structure

[Table] Attribute

[Column] Attribute

[PropertyOrder] Attribute