防爆$ P $类型'System.Int32的“的pssion不能用于类型参数'System.Object的'法'布尔等于（System.Object的）'类型
2023-09-05 03:30:17
作者：看透卜说透 ∞
我有一个共同的网格视图列过滤器的方法，与的ColumnName和SearchText明智的过滤器网格视图记录。这里的时候，我可为空INT DataColumn的操作存在误差从此方法抛出这样的：
防爆$类型'System.Int32的的对$ pssion不能用于类型参数'System.Object的'法'布尔等于（System.Object的）'
我的方法code是：
公共静态的IQueryable＆LT; T＆GT; FilterForColumn＆LT; T＆GT;（这IQueryable的＆LT; T＆GT;可查询字符串COLNAME，串searchText）
{
如果（COLNAME = NULL和放大器;！＆安培;！searchText = NULL）
{
VAR参数=前pression.Parameter（typeof运算（T），M）;
VAR propertyEx pression =前pression.Property（参数COLNAME）;
System.Linq.Ex pressions.ConstantEx pression searchEx pression = NULL;
System.Reflection.MethodInfo containsMethod = NULL;
//这必须是防爆型$ P $ pssion接受不同类型的EX pressions
//即BinaryEx pression，MethodCallEx pression，...
System.Linq.Ex pressions.Ex pression体= NULL;
防爆pression EX1 = NULL;
防爆pression EX2 = NULL;
开关（COLNAME）
{
案作业ID：
案status_id：
INT32 _INT = Convert.ToInt32（searchText）;
searchEx pression =前pression.Constant（_INT）;
containsMethod = typeof运算（Int32）已.GetMethod（等于，新的[] {typeof运算（Int32）已}）;
身体=前pression.Call（propertyEx pression，containsMethod，searchEx pression）;
打破;
案GROUP_ID：
INT32？ _int1 = Convert.ToInt32（searchText）;
searchEx pression =前pression.Constant（_int1）;
。containsMethod = typeof运算（？Int32）在GetMethod的（等于，新的[] {typeof运算（Int32）已？}）;
//错误，从该行抛出
身体=前pression.Call（propertyEx pression，containsMethod，searchEx pression）;
打破;
案文件大小：
案TotalFileSize：
Int64的？ _int2 = Convert.ToInt64（searchText）;
searchEx pression =前pression.Constant（_int2）;
。containsMethod = typeof运算（？的Int64）GetMethod的（等于，新的[] {typeof运算（Int64的）？}）;
身体=前pression.Call（propertyEx pression，containsMethod，searchEx pression）;
打破;
//节日期时间？性能
案PublishDate：
案Birth_date：
案Anniversary_date：
案Profile_Updated_datetime：
案CompletedOn：
日期时间的currentdate = DateTime.ParseExact（searchText，DD / MM / YYYY，NULL）;
日期时间nextDate = currentDate.AddDays（1）;
EX1 =前pression.GreaterThanOrEqual（propertyEx pression，防爆pression.Constant（的currentdate的typeof（DateTime的）））;
EX2 =前pression.LessThan（propertyEx pression，防爆pression.Constant（nextDate的typeof（DateTime的）））;
身体=前pression.AndAlso（EX1，EX2）;
打破;
//节日期时间属性
案Created_datetime：
案Reminder_Date：
案News_date：
案thought_date：
案SubscriptionDateTime：
案Register_datetime：
案CreatedOn：
日期时间currentDate1 = DateTime.ParseExact（searchText，DD / MM / YYYY，NULL）;
日期时间nextDate1 = currentDate1.AddDays（1）;
EX1 =前pression.GreaterThanOrEqual（propertyEx pression，防爆pression.Constant（currentDate1））;
EX2 =前pression.LessThan（propertyEx pression，防爆pression.Constant（nextDate1））;
身体=前pression.AndAlso（EX1，EX2）;
打破;
默认：
searchEx pression =前pression.Constant（searchText）;
containsMethod = typeof运算（字符串）.GetMethod（包含，新的[] {typeof运算（字符串）}）;
身体=前pression.Call（propertyEx pression，containsMethod，searchEx pression）;
打破;
}
VAR predicate =前pression.Lambda＆LT; Func键＆LT; T，布尔＆GT;＆GT;（身体，新的[] {参数}）;
返回queryable.Where（predicate）;
}
其他
{
返回可查询;
}
}
这是我的查询，我解雇了：
VAR的查询= Helper.GetUsers（）式（U =＆GT;！u.Id = USER_ID）。.OrderByDescending（U =＆GT; u.Register_datetime）。选择（U = ＆gt;新建
{
n = u.Id，
名称= u.First_name ++ u.Last_name，
IsActive = u.IsActive，
IsVerified = u.IsVerified，
用户名= u.Username，
密码= u.password，
Birth_date = u.Birth_date，
Anniversary_date = u.Anniversary_date，
status_id = u.status_id，
GROUP_ID = u.group_id，
Profile_Updated_datetime = u.Profile_Updated_datetime，
Register_datetime = u.Register_datetime
}）FilterForColumn（的ColumnName，SearchText）.ToList（）。
在这里，我有我的query.GetType（）。toString（）方法得到更好地理解类型的列，我就可以进行操作。
System.Collections.Generic.List`1[<>f__AnonymousType0`12[System.Int32,System.String,System.Boolean,System.Boolean,System.String,System.String,System.Nullable`1[System.DateTime],System.Nullable`1[System.DateTime],System.Int32,System.Nullable`1[System.Int32],System.Nullable`1[System.DateTime],System.DateTime]]解决方案
修改
在找到this问题。您需要调用等于之前（对象）方法转换前pression到对象：
VAR转换=前pression.Convert（searchEx pression的typeof（对象））;
身体=前pression.Call（propertyEx pression，containsMethod，转换）;
倪codemus13 的明确设置的建议 searchEx pression 的类型在首位对象应该工作了。
原
我还没有发现这个问题，但我已经转载使用Linqpad在SSCCE问题：
无效的主要（）
{
VAR将myInstance =新MyClass的（）;
。VAR equalsMethod = typeof运算（？Int32）在GetMethod的（等于，新的[] {typeof运算（Int32）已？}）;
诠释？ nullableInt = 1;
VAR nullableIntExpr = System.Linq.Ex pressions.Ex pression.Constant（nullableInt）;
VAR myInstanceExpr = System.Linq.Ex pressions.Ex pression.Constant（将myInstance）;
VAR propertyExpr = System.Linq.Ex pressions.Ex pression.Property（myInstanceExpr，myProperty的）;
VAR的结果=前pression.Call（propertyExpr，equalsMethod，nullableIntExpr）; //这行抛出异常。
Console.WriteLine（结果）;
}
MyClass类{公众诠释？ {myProperty的获取;设置;}}
这行：
containsMethod = typeof运算（？Int32）在GetMethod的（等于，新的[] {typeof运算（Int32）已？}）。
返回的MethodInfo 的方法的Int32？.Equals（对象等）。注意参数类型为对象，不是的Int32 （或的Int32？）如你所期望的。
原因是的typeof（的Int32？）是 System.Nullable＆LT;的Int32＆GT; ，其不仅具有等于（对象）方法。
i have one common grid view column filter method that filter grid view record with ColumnName and SearchText wise. here when i operate on nullable int datacolumn there is error thrown from this method like :
Expression of type 'System.Int32' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)'
my method code is :
public static IQueryable<T> FilterForColumn<T>(this IQueryable<T> queryable, string colName, string searchText)
{
if (colName != null && searchText != null)
{
var parameter = Expression.Parameter(typeof(T), "m");
var propertyExpression = Expression.Property(parameter, colName);
System.Linq.Expressions.ConstantExpression searchExpression = null;
System.Reflection.MethodInfo containsMethod = null;
// this must be of type Expression to accept different type of expressions
// i.e. BinaryExpression, MethodCallExpression, ...
System.Linq.Expressions.Expression body = null;
Expression ex1 = null;
Expression ex2 = null;
switch (colName)
{
case "JobID":
case "status_id":
Int32 _int = Convert.ToInt32(searchText);
searchExpression = Expression.Constant(_int);
containsMethod = typeof(Int32).GetMethod("Equals", new[] { typeof(Int32) });
body = Expression.Call(propertyExpression, containsMethod, searchExpression);
break;
case "group_id":
Int32? _int1 = Convert.ToInt32(searchText);
searchExpression = Expression.Constant(_int1);
containsMethod = typeof(Int32?).GetMethod("Equals", new[] { typeof(Int32?) });
//Error throws from this line
body = Expression.Call(propertyExpression, containsMethod, searchExpression);
break;
case "FileSize":
case "TotalFileSize":
Int64? _int2 = Convert.ToInt64(searchText);
searchExpression = Expression.Constant(_int2);
containsMethod = typeof(Int64?).GetMethod("Equals", new[] { typeof(Int64?) });
body = Expression.Call(propertyExpression, containsMethod, searchExpression);
break;
// section for DateTime? properties
case "PublishDate":
case "Birth_date":
case "Anniversary_date":
case "Profile_Updated_datetime":
case "CompletedOn":
DateTime currentDate = DateTime.ParseExact(searchText, "dd/MM/yyyy", null);
DateTime nextDate = currentDate.AddDays(1);
ex1 = Expression.GreaterThanOrEqual(propertyExpression, Expression.Constant(currentDate, typeof(DateTime?)));
ex2 = Expression.LessThan(propertyExpression, Expression.Constant(nextDate, typeof(DateTime?)));
body = Expression.AndAlso(ex1, ex2);
break;
// section for DateTime properties
case "Created_datetime":
case "Reminder_Date":
case "News_date":
case "thought_date":
case "SubscriptionDateTime":
case "Register_datetime":
case "CreatedOn":
DateTime currentDate1 = DateTime.ParseExact(searchText, "dd/MM/yyyy", null);
DateTime nextDate1 = currentDate1.AddDays(1);
ex1 = Expression.GreaterThanOrEqual(propertyExpression, Expression.Constant(currentDate1));
ex2 = Expression.LessThan(propertyExpression, Expression.Constant(nextDate1));
body = Expression.AndAlso(ex1, ex2);
break;
default:
searchExpression = Expression.Constant(searchText);
containsMethod = typeof(string).GetMethod("Contains", new[] { typeof(string) });
body = Expression.Call(propertyExpression, containsMethod, searchExpression);
break;
}
var predicate = Expression.Lambda<Func<T, bool>>(body, new[] { parameter });
return queryable.Where(predicate);
}
else
{
return queryable;
}
}
here is my query that i fired :
var query = Helper.GetUsers().Where(u => u.Id != user_id).OrderByDescending(u => u.Register_datetime).Select(u => new
{
Id = u.Id,
Name = u.First_name + " " + u.Last_name,
IsActive = u.IsActive,
IsVerified = u.IsVerified,
Username = u.Username,
password = u.password,
Birth_date = u.Birth_date,
Anniversary_date = u.Anniversary_date,
status_id = u.status_id,
group_id = u.group_id,
Profile_Updated_datetime = u.Profile_Updated_datetime,
Register_datetime = u.Register_datetime
}).FilterForColumn(ColumnName, SearchText).ToList();
here i include my query.GetType().ToString() result for better understanding types of columns that i operate on it.
System.Collections.Generic.List`1[<>f__AnonymousType0`12[System.Int32,System.String,System.Boolean,System.Boolean,System.String,System.String,System.Nullable`1[System.DateTime],System.Nullable`1[System.DateTime],System.Int32,System.Nullable`1[System.Int32],System.Nullable`1[System.DateTime],System.DateTime]]
解决方案
EDIT
Found the solution in this question. You need to convert the expression to Object before calling the Equals(object)method:
var converted = Expression.Convert(searchExpression, typeof(object));
body = Expression.Call(propertyExpression, containsMethod, converted);
Nicodemus13's suggestion of explicitly setting searchExpression's type to Object in the first place should work, too.
Original
I haven't found the issue yet, but I have reproduced the problem in a SSCCE using Linqpad:
void Main()
{
var myInstance = new myClass();
var equalsMethod = typeof(Int32?).GetMethod("Equals", new[] { typeof(Int32?) });
int? nullableInt = 1;
var nullableIntExpr = System.Linq.Expressions.Expression.Constant(nullableInt);
var myInstanceExpr = System.Linq.Expressions.Expression.Constant(myInstance);
var propertyExpr = System.Linq.Expressions.Expression.Property(myInstanceExpr, "MyProperty");
var result = Expression.Call(propertyExpr,equalsMethod,nullableIntExpr); // This line throws the exception.
Console.WriteLine(result);
}
class myClass{public int? MyProperty{get;set;}}
This line:
containsMethod = typeof(Int32?).GetMethod("Equals", new[] { typeof(Int32?) });
returns a MethodInfo for the method Int32?.Equals (Object other). Notice the parameter type is object, not Int32 (or Int32?) as you might expect.
The reason is typeof(Int32?) is System.Nullable<Int32>, which only has the Equals(object) method.
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