/// <summary>
/// 从数据库读取 必须有Key特性
/// </summary>
/// <param name="dataEntity">数据实体</param>
public static bool Read <T>(this IDataEntity <T> dataEntity) where T : DbContext, new()
{
var context = dataEntity.GetDbContext();
var properties = dataEntity.GetType().GetProperties();
var result = false;
object model = null;
foreach (var item in properties)
{
if (item.GetCustomAttribute(typeof(KeyAttribute)) != null)
{
var keyValue = item.GetValue(dataEntity);
model = context.Set(dataEntity.GetType()).Find(keyValue);
break;
}
}
if (model != null)
{
result = true;
foreach (var item in properties)
{
item.SetValue(dataEntity, item.GetValue(model));
}
}
return(result);
}
/// <summary>
/// 更新数据实体值到数据库
///备注: 根据当前数据对象的值向数据库插入一条数据库记录。如果没有为对象添加任何属性，则不会产生任何效果。
/// </summary>
/// <param name="dataEntity">数据实体</param>
public static void Update <T>(this IDataEntity <T> dataEntity) where T : DbContext, new()
{
var context = dataEntity.GetDbContext();
context.Set(dataEntity.GetType()).Attach(dataEntity);
context.Entry(dataEntity).State = EntityState.Modified;
context.SaveChanges();
}
/// <summary>
/// 判断数据实体是否在数据库中存在 必须有Key特性
/// </summary>
/// <param name="dataEntity">数据实体</param>
public static bool ExistsInDb <T>(this IDataEntity <T> dataEntity) where T : DbContext, new()
{
var context = dataEntity.GetDbContext();
var properties = dataEntity.GetType().GetProperties();
foreach (var item in properties)
{
if (item.GetCustomAttribute(typeof(KeyAttribute)) != null)
{
var keyValue = item.GetValue(dataEntity);
var model = context.Set(dataEntity.GetType()).Find(keyValue);
if (model == null)
{
return(false);
}
else
{
return(true);
}
}
}
throw new Exception("未找到实体类主键");
}
/// <summary>
/// 实体查询
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="dataEntity">数据实体</param>
/// <param name="where">数据查询条件</param>
/// <param name="skip"></param>
/// <param name="count"></param>
/// <returns></returns>
public static IQueryable <TEntity> Select <TEntity, T>(this IDataEntity <T> dataEntity, Expression <Func <TEntity, bool> > where, int skip, int count) where T : DbContext, new() where TEntity : class, IDataEntity <T>, new()
{
return(dataEntity.GetDbContext().Set <TEntity>().Where(where).Skip(skip).Take(count));
}
/// <summary>
/// 实体查询
/// </summary>
/// <typeparam name="T">实体类型</typeparam>
/// <param name="dataEntity">数据实体</param>
/// <returns>符合条件的数据对象</returns>
public static IQueryable <TEntity> Select <TEntity, T>(this IDataEntity <T> dataEntity) where T : DbContext, new() where TEntity : class, IDataEntity <T>, new()
{
return(dataEntity.GetDbContext().Set <TEntity>().Where(m => true));
}