Say I have the following model:
[Table("Record")]
public class RecordModel
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
[Display(Name = "Record Id")]
public int RecordId { get; set; }
[StringLength(150)]
public string Name { get; set; }
[Required]
[StringLength(15)]
public string IMEI { get; set; }
}
Is it possible to add an index to the IMEI column through using an attribute, data annotation, or something from the model?
In EF Core 5, the Index attribute should be placed on the class.
See: MSDN
[Index(nameof(Url))]
public class Post
{
public int PostId { get; set; }
public string Url { get; set; }
public string Title { get; set; }
public DateTime PublishedOn { get; set; }
}
or revert to the fluent syntax for more advanced option:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Post>()
.HasIndex(p => p.Url)
.IncludeProperties(
p => new { p.Title, p.PublishedOn });
}
Since the release of EF 6.1. (March 17th, 2014) there is indeed an [Index] attribute available.
Functionality as:
[Index("IMEIIndex", IsUnique = true)]
public string IMEI { get; set; }
comes out of the box.
PS: other properties are Order and IsClustered.
According to this link: http://blogs.msdn.com/b/adonet/archive/2014/02/11/ef-6-1-0-beta-1-available.aspx
It will be available in EF 6.1 as a standard DataAnnotation attribute.
IndexAttribute allows indexes to be specified by placing an [Index] attribute on a property (or properties) in your Code First model. Code First will then create a corresponding index in the database.
According to this link: Creating Indexes via Data Annotations with Entity Framework 5.0 you should write some kind of extension code:
using System;
[AttributeUsage(AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
public class IndexAttribute : Attribute
{
public IndexAttribute(string name, bool unique = false)
{
this.Name = name;
this.IsUnique = unique;
}
public string Name { get; private set; }
public bool IsUnique { get; private set; }
}
and the second class:
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity;
using System.Linq;
using System.Reflection;
public class IndexInitializer<T> : IDatabaseInitializer<T> where T : DbContext
{
private const string CreateIndexQueryTemplate = "CREATE {unique} INDEX {indexName} ON {tableName} ({columnName})";
public void InitializeDatabase(T context)
{
const BindingFlags PublicInstance = BindingFlags.Public | BindingFlags.Instance;
foreach (var dataSetProperty in typeof(T).GetProperties(PublicInstance).Where(
p => p.PropertyType.Name == typeof(DbSet<>).Name))
{
var entityType = dataSetProperty.PropertyType.GetGenericArguments().Single();
TableAttribute[] tableAttributes = (TableAttribute[])entityType.GetCustomAttributes(typeof(TableAttribute), false);
foreach (var property in entityType.GetProperties(PublicInstance))
{
IndexAttribute[] indexAttributes = (IndexAttribute[])property.GetCustomAttributes(typeof(IndexAttribute), false);
NotMappedAttribute[] notMappedAttributes = (NotMappedAttribute[])property.GetCustomAttributes(typeof(NotMappedAttribute), false);
if (indexAttributes.Length > 0 && notMappedAttributes.Length == 0)
{
ColumnAttribute[] columnAttributes = (ColumnAttribute[])property.GetCustomAttributes(typeof(ColumnAttribute), false);
foreach (var indexAttribute in indexAttributes)
{
string indexName = indexAttribute.Name;
string tableName = tableAttributes.Length != 0 ? tableAttributes[0].Name : dataSetProperty.Name;
string columnName = columnAttributes.Length != 0 ? columnAttributes[0].Name : property.Name;
string query = CreateIndexQueryTemplate.Replace("{indexName}", indexName)
.Replace("{tableName}", tableName)
.Replace("{columnName}", columnName)
.Replace("{unique}", indexAttribute.IsUnique ? "UNIQUE" : string.Empty);
context.Database.CreateIfNotExists();
context.Database.ExecuteSqlCommand(query);
}
}
}
}
}
}
After it you can use your index this way:
[Required]
[Index("IMEIIndex", unique: true)]
[StringLength(15)]
public string IMEI { get; set; }
Index? If I try to use this [Index("IMEIIndex", unique: true)] it asks me to generate my own Index classDatabase.SetInitializer(new IndexInitializer<DbContext>()); in your OnModelCreating of the dbcontext