c# – 首先从实体框架6数据库中的数据库中获取列名,并在映射中使

发布时间：2020-12-15 23:22:28 所属栏目：百科来源：网络整理

导读：我遇到的情况是我的表名与使用EF 6中的映射的模型上的类属性不同.模型和数据库如下所示： public class AGENTMap : EntityTypeConfigurationAGENT{ public AGENTMap() { // Primary Key this.HasKey(t = new {t.AgentCode }); // Properties this.Property(t

我遇到的情况是我的表名与使用EF 6中的映射的模型上的类属性不同.模型和数据库如下所示：

public class AGENTMap : EntityTypeConfiguration<AGENT>
{
    public AGENTMap()
    {
        // Primary Key
        this.HasKey(t => new {t.AgentCode });

        // Properties
        this.Property(t => t.AgentCode)
            .HasMaxLength(10);

        this.Property(t => t.AgentName)
            .HasMaxLength(30);


        // Table & Column Mappings
        this.ToTable("AGENT");
        this.Property(t => t.agent_cd).HasColumnName("agent_cd");
        this.Property(t => t.agent_nm).HasColumnName("agent_nm");
    }
}

这相当于具有这些属性的AGENT类.
问题是当我尝试使用此代码段获取主键时：

ObjectContext objectContext = ((IObjectContextAdapter)_context).ObjectContext;
        ObjectSet<TEntity> objSet = objectContext.CreateObjectSet<TEntity>();
        IEnumerable<string> keyNames = objSet.EntitySet.ElementType.KeyMembers
            .Where(p => p.MetadataProperties.Any(m => m.PropertyKind == PropertyKind.Extended
                              && Convert.ToString(m.Value) == "Identity"))
                                                    .Select(e => e.Name).ToList();

        return keyNames;

它返回Mapping类的Property Name.我想得到“agent_cd”..这是db列名.在EF6中是否有办法在Db上获取确切的列名？

解决方法

Rowan Miller wrote another blog post准确显示了如何在EF 6中获取列名.

public static string GetColumnName(Type type,string propertyName,DbContext context)
{
    var metadata = ((IObjectContextAdapter)context).ObjectContext.MetadataWorkspace;

    // Get the part of the model that contains info about the actual CLR types
    var objectItemCollection = ((ObjectItemCollection)metadata.GetItemCollection(DataSpace.OSpace));

    // Get the entity type from the model that maps to the CLR type
    var entityType = metadata
            .GetItems<EntityType>(DataSpace.OSpace)
            .Single(e => objectItemCollection.GetClrType(e) == type);

    // Get the entity set that uses this entity type
    var entitySet = metadata
        .GetItems<EntityContainer>(DataSpace.CSpace)
        .Single()
        .EntitySets
        .Single(s => s.ElementType.Name == entityType.Name);

    // Find the mapping between conceptual and storage model for this entity set
    var mapping = metadata.GetItems<EntityContainerMapping>(DataSpace.CSSpace)
            .Single()
            .EntitySetMappings
            .Single(s => s.EntitySet == entitySet);

    // Find the storage entity set (table) that the entity is mapped
    var tableEntitySet = mapping
        .EntityTypeMappings.Single()
        .Fragments.Single()
        .StoreEntitySet;

    // Return the table name from the storage entity set
    var tableName = tableEntitySet.MetadataProperties["Table"].Value ?? tableEntitySet.Name;

    // Find the storage property (column) that the property is mapped
    var columnName = mapping
        .EntityTypeMappings.Single()
        .Fragments.Single()
        .PropertyMappings
        .OfType<ScalarPropertyMapping>()
        .Single(m => m.Property.Name == propertyName)
        .Column
        .Name;

    return tableName + "." + columnName;
}

（编辑：李大同）

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