EFCore多字段排序分页法
模型：
public class IPageCommand
{
public string Keyword { get; set; }
public int PageIndex { get; set; }
public int PageSize { get; set; }
public OrderModelField[] OrderModelField { get; set; }
}
public struct OrderModelField
{
public string SortField { get; set; }
public bool IsDesc { get; set; }
}
⽅法：
sort of order///<summary>
///根据条件获取多个实体
///</summary>
///<param name="where"></param>
///<returns></returns>
public List<TResult> GetPageList<TEntity, TResult>(Expression<Func<TEntity, TResult>> select, Expression<Func<TEntity, bool>> where, int pageIndex, int pageSize, out long total, params OrderModelField[] orderByExpression) where TEntity : class
{
//条件过滤
var query = _context.Set<TEntity>().Where(where);
//创建表达式变量参数
var parameter = Expression.Parameter(typeof(TEntity), "o");
if (orderByExpression != null && orderByExpression.Length > 0)
{
for (int i = 0; i < orderByExpression.Length; i++)
{
//根据属性名获取属性
var property = typeof(TEntity).GetProperty(orderByExpression[i].SortField);
/
/创建⼀个访问属性的表达式
var propertyAccess = Expression.MakeMemberAccess(parameter, property);
var orderByExp = Expression.Lambda(propertyAccess, parameter);
string OrderName = "";
if (i > 0)
OrderName = orderByExpression[i].IsDesc ? "ThenByDescending" : "ThenBy";
else
OrderName = orderByExpression[i].IsDesc ? "OrderByDescending" : "OrderBy";
MethodCallExpression resultExp = Expression.Call(typeof(Queryable), OrderName, new Type[] { typeof(TEntity), property.PropertyType }, query.Expression, Expression.Quote(orderByExp));
query = query.Provider.CreateQuery<TEntity>(resultExp);
}
}
total = query.Count();
return query.Skip((pageIndex - 1) * pageSize).Take(pageSize).Select(select).ToList();
}
参数：
{
"Keyword": "string",
"PageIndex": 2,
"PageSize": 5,
"OrderModelField": [
{
"SortField": "CreateTime",
"IsDesc": true},
{
"SortField": "String",
"IsDesc": true}
]
}
调⽤：
public List<ExampleResult> GetList(PagedCommand Cmd, long total)
{
return GetPageList<ExampleEntity, ExampleResult>(x => new ExampleResult
{
Id = x.Id,
Boolean = x.Boolean,
CreateTime = x.CreateTime,
Decimal = x.Decimal,
Enum = x.Enum,
Float = x.Float,
Int = x.Int,
String = x.String
}, x => x.Boolean, Cmd.PageIndex, Cmd.PageSize, out total, Cmd.OrderModelField);
}

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