entity-framework – 使用Entity Framework创建数据库索引

[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; }
}

通过使用属性,数据注释或模型中的某些东西,可以向IMEI列添加索引吗？

解决方法

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; }
}

和第二类：

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);
                    }
                }
            }
        }
    }
}

之后,您可以使用您的索引：

[Required]
[Index("IMEIIndex",unique: true)]
[StringLength(15)]
public string IMEI { get; set; }

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!