使用Entity Framework创建数据库索引 [英] Create database index with Entity Framework

问题描述

说我有以下模式：

  [Table（Record）] 
 public class RecordModel 
 {
 [Key] 
 [DatabaseGeneratedAttribute（DatabaseGeneratedOption.Identity）] 
 [Display（Name =Record Id）] 
 public int RecordId {get;组; } 
 
 [StringLength（150）] 
 public string Name {get;组; 
 
 [必需] 
 [StringLength（15）] 
 public string IMEI {get;组; } 
} 
  

是否可以向 IMEI 列通过使用属性，数据注释或模型中的某些东西？

解决方案

根据此链接：通过实体框架5.0的数据注释创建索引
您应该写一些类型的扩展代码：

  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;私人集合} 
 
 public bool IsUnique {get;私人集合
} 
  

而第二类：

 使用System.ComponentModel.DataAnnotations.Schema; 
使用System.Data.Entity; 
使用System.Linq; 
使用System.Reflection; 
 
 public class IndexInitializer< T> ：IDatabaseInitializer< T>其中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& 
 {
 var entityType = dataSetProperty.PropertyType.GetGenericArguments（）。Single（）; 
 
 TableAttribute [] tableAttributes =（TableAttribute []）entityType.GetCustomAttributes（typeof（TableAttribute），false）; 
 
 foreach（entityType.GetProperties（PublicInstance）中的var属性）
 {
 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） ，假）; 
 
 foreach（indexAttributes中的var indexAttribute）
 {
 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，您可以使用索引：

 
 [StringLength（15）] 
 public string IMEI {get;组; } 
  

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?

解决方案

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; }

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