/// <summary>
/// 筛选满足条件的项并给指定字段赋值
/// </summary>
/// <typeparam name="TAggregateRoot"></typeparam>
/// <typeparam name="TField"></typeparam>
/// <param name="item"></param>
/// <param name="field"></param>
/// <param name="value"></param>
/// <returns></returns>
public static IQueryable <TAggregateRoot> Set <TAggregateRoot, TField>(this IQueryable <TAggregateRoot> item,
Expression <Func <TAggregateRoot, TField> > field, TField value) where TAggregateRoot : class, new()
{
if (field != null)
{
if (!(field.Body is MemberExpression exp) || field.Parameters.Count == 0)
{
throw new Exception("无效的Lambda表达式");
}
var ext = new EmitExtension <TAggregateRoot>();
ext.BuildEmitMethod(typeof(TAggregateRoot), exp.Member.Name);
item.ToList().ForEach(x => ext.EmitSetValue(x, value));
}
else
{
throw new Exception("无效的Lambda表达式");
}
return(item);
}
public static IQueryable <TAggregateRoot> Set <TAggregateRoot>(this IQueryable <TAggregateRoot> tAggregateRoots,
Expression <Func <TAggregateRoot, TAggregateRoot> > tAggregateRoot)
where TAggregateRoot : class, new()
{
if (tAggregateRoot != null)
{
var exp = tAggregateRoot.Body as MemberInitExpression;
if (exp == null || exp.Bindings.Count == 0)
{
throw new Exception("无效的Lambda表达式");
}
foreach (var binding in exp.Bindings)
{
var ext = new EmitExtension <TAggregateRoot>();
ext.BuildEmitMethod(typeof(TAggregateRoot), binding.Member.Name);
var memberAssignment = binding as MemberAssignment;
if (memberAssignment == null)
{
throw new ArgumentException("表达式必须为MemberAssignment");
}
Expression memberExpression = memberAssignment.Expression;
ParameterExpression parameterExpression = null;
memberExpression.Visit((ParameterExpression p) =>
{
parameterExpression = p;
return(p);
});
object value = null;
if (parameterExpression == null)
{
if (memberExpression.NodeType == ExpressionType.Constant)
{
var constantExpression = memberExpression as ConstantExpression;
if (constantExpression == null)
{
throw new ArgumentException(
"MemberAssignment expression 无效");
}
value = constantExpression.Value;
}
else
{
var lambda = Expression.Lambda(memberExpression, null);
value = lambda.Compile().DynamicInvoke();
}
}
else
{
throw new Exception("无效的Lambda表达式");
}
tAggregateRoots.ToList().ForEach(x => ext.EmitSetValue(x, value));
}
}
else
{
throw new Exception("无效的Lambda表达式");
}
return(tAggregateRoots);
}
