Question

如何拼接Expression查询条件

Answer 1

转换下，大概如下：
var expression = Expression.Equal(Expression.Constant(1), Expression.Constant(1));
var parameterExpression = Expression.Parameter(typeof(Model.PM_PickStore), "p");
var propertyExpression = Expression.Property(parameterExpression, "DevID");
if (PlanNo == "") { expression = Expression.AndAlso(expression, Expression.Equal(propertyExpression, Expression.Constant(1)));}
if (PlanNo == "") { expression = Expression.AndAlso(expression, Expression.Equal(propertyExpression, Expression.Constant(2))); }
if (PlanNo == "") { expression = Expression.AndAlso(expression, Expression.Equal(propertyExpression, Expression.Constant(3))); }