检查字符串是否可以转换为给定类型

时间：2017-10-08 17:45:07

标签： c#

我必须创建一个API，如果他没有在 GET 请求中提供强制参数，我需要向用户提供正确的消息，我还需要确保用户已经在参数中提供了适当的值，值可以是整数，字符串，日期或枚举。

所以我创建了一个类 SearchParameters ，其中列出了有关请求参数的信息。

private static class SearchParameters
{
    public static List<ParamInfo> ParamList = new List<ParamInfo>
    {
        new ParamInfo {Name ="location", IsMandatory = true , ExpecteDataType = typeof(ulong) } ,
        new ParamInfo {Name ="service", IsMandatory = true  , ExpecteDataType = typeof(ServiceType)} ,
        new ParamInfo {Name ="start", IsMandatory = true  , ExpecteDataType = typeof(DateTimeOffset)} ,
        new ParamInfo {Name ="appointmentType", IsMandatory = true  , ExpecteDataType = typeof(AppointmentType)} ,
        new ParamInfo {Name ="status", IsOptional = true  , ExpecteDataType = typeof(string)} ,
        new ParamInfo {Name ="end", IsOptional = true  , ExpecteDataType = typeof(DateTimeOffset)} ,
        new ParamInfo {Name ="clinicianGender", IsOptional = true , ExpecteDataType = typeof(AdministrativeGender)}   ,
        new ParamInfo {Name ="_sort", IsForSorting = true , ExpecteDataType = typeof(string)},
        new ParamInfo {Name ="_count", IsForPaging = true , ExpecteDataType = typeof(uint)}
    };
}

其中ParamInfo是类

的实例 
public class ParamInfo
{
    public string Name { get; set; }
    public bool IsMandatory { get; set; }
    public bool IsRequired { get; set; }
    public bool IsOptional { get; set; }
    public bool IsForSorting { get; set; }
    public bool IsForPaging { get; set; }
    public Type ExpecteDataType { get; set; }
}

当用户请求时，我在元组列表中有可用的参数Item1＆amp; Item2是字符串，Item1是查询参数＆amp;的名称。 Item2是用户提供的值。

如何确保参数（即Item2）的值具有正确的数据类型？

我试过这样的事情：

// Data tye verification
foreach (ParamInfo info in SlotSearchParameters.ParamList)
{
    Tuple<string, string> param = searchparams.Parameters.Where(x => x.Item1.ToLower() == info.Name).FirstOrDefault();
    if (param != null)
    {
        Type expectedType = info.ExpecteDataType;
        // how can we check if the value of type of x.Item1 is as expected 
        // Can't procede
    }
}

但由于x.Item1始终是所提供值的字符串表示形式，可以是Date，Int或string等，我不知道该怎么做？

3 个答案:

答案 0 :(得分：2)

您可以在ParamInfo课程中添加验证器：

public class ParamInfo
{
    public string Name { get; set; }
    public bool IsMandatory { get; set; }
    public bool IsRequired { get; set; }
    public bool IsOptional { get; set; }
    public bool IsForSorting { get; set; }
    public bool IsForPaging { get; set; }
    public Type ExpecteDataType { get; set; }
    public Predicate<string> Validator { get; set; }
}

现在：

public static List<ParamInfo> ParamList = new List<ParamInfo>
{
    new ParamInfo { Name ="location",
                   IsMandatory = true, 
                   ExpecteDataType = typeof(ulong),
                   Validator = s => s != null && ulong.TryParse(s, out var _); }

你可以像这样使用它：

foreach (ParamInfo info in SlotSearchParameters.ParamList)
{
    Tuple<string, string> param = searchparams.Parameters.Where(x => x.Item1.ToLower() == info.Name).FirstOrDefault();

    if (param != null &&
        Validator(x.Item1) //
    {
        //whatever
    }
}

}

答案 1 :(得分：1)

出于问题中所述的目的，您应使用#include <stdio.h> char **createMapBoard(void); void printMapBoard(char **board); char **destroyMapBoard(char **board); int main(){ char **board = createMapBoard(); printMapBoard(board); destroyMapBoard(board); printMapBoard(board); return 0; } char **createMapBoard(void){ char **ptr[8][8]; int i,j; char F = 'F'; char K = 'K'; char C = 'C'; char D = 'D'; char B = 'B'; int n = 8; int m = 8; for(j=0; j<8; j++){ for(i=0;i<8;i++){ ptr[j][i] = ' '; } } ptr[0][0] = F; ptr[0][1] = F; ptr[1][1] = F; ptr[2][1] = F; ptr[2][2] = F; ptr[3][2] = F; ptr[4][2] = K; ptr[5][0] = C; ptr[5][3] = B; ptr[6][1] = C; ptr[6][2] = C; ptr[6][4] = D; ptr[7][2] = C; ptr[7][5] = D; ptr[7][6] = D; printf("========\n"); for(j=0;j<8;j++){ for(i=0;i<8;i++){ printf("%c",ptr[j][i]); } printf("\n"); } printf("========\n"); printf("\n"); return **ptr; } void printMapBoard(char **board){ int j, i; printf("========\n"); for(j=0;j<8;j++){ for(i=0;i<8;i++){ printf("%c", board[j][i]); } printf("\n"); } printf("========\n"); printf("\n"); } char **destroyMapBoard(char **board){ free(**board); free(board); return 0; } （re：https://msdn.microsoft.com/en-us/library/system.int32.parse(v=vs.110).aspx）或Parse()（re：https://msdn.microsoft.com/en-us/library/zf50za27(v=vs.110).aspx）方法，例如TryParse()

希望这会有所帮助。

答案 2 :(得分：0)

  

如何确保参数（即Item2）的值具有正确的数据类型？

  1. 您可以让用户很难实际输入错误的数据类型。例如，如果他们在表单中键入内容并且您要求输入日期 - 如果他们在该字段中输入非感性内容，请将其设置为无法提交表单。
  2. 如果他们输入非感性或
    3. 的内容，您可以抛出异常
  3. 如果输入值不是正版，则可以阻止创建ParamInfo对象。请参阅下面的一些示例。
  4. 附注：您实际将数据存储在ParamInfo类中的哪个位置？如果您实际上将变量存储为int，date或enum等，那么使用此变量就可以避免使用ExpectedDataType变量。我希望这是有道理的。换句话说，您是否要将item1.value存储为ParamInfo类中的字符串？或者您想存储的是实际数字，日期还是枚举？
  5. 用户是否可能意外输入错误的ParamInfo.Name值？

    6. 无论如何，这里有一些想法可以帮助你：

    internal class Program
{
    private static void Main(string[] args)
    {
        List<Tuple<string, string>> userInputValues = new List<Tuple<string, string>>(); // obviously implement the correct user values here

        // This is the money below.
        // you'll have only valid ParamInfo objects here:

        List<ParamInfo> paramFactory = new ParamInfoFactory(userInputValues).ValidParameters;         
    }

    public class ParamInfo
    {
        public string Name { get; set; }
        public bool IsMandatory { get; set; }
        public bool IsRequired { get; set; }
        public bool IsOptional { get; set; }
        public bool IsForSorting { get; set; }
        public bool IsForPaging { get; set; }

        public Type ExpecteDataType { get; set; } // <--- you really don't need this.

        // where are you storing the item1.value?
        // are you storing it as a string, or as the proper type that it represents?
    }
    public class ParamInfoFactory
    {
        public List<ParamInfo> ValidParameters { get; set; }

        public ParamInfoFactory(List<Tuple<string, string>> userSuppliedValues)
        {
            ValidParameters = new List<ParamInfo>();
            foreach (Tuple<string, string> userValue in userSuppliedValues)
            {
                if (UserInputValuesAreValid(userValue))
                {
                    // all the values are valid. you can now create and add the parameters to your list.
                    // remember to instantiate it as you wish with the right values etc in there.
                    ValidParameters.Add(new ParamInfo());
                }
            }
        }
        private bool UserInputValuesAreValid(Tuple<string, string> userValue)
        {
            return IsNameValid(userValue.Item1) && IsDataValid(userValue.Item2);
        }

        private bool IsDataValid(string data)
        {
            return IsValidDate(data) || IsValidNumber(data); // you can also implement the IsValidEnum or any other method you want
        }

        private static bool IsValidDate(string data)
        {
            DateTime dateValue;
            bool isDate = DateTime.TryParse(data, out dateValue);
            return isDate;
        }

        //private static bool IsEnum(string data)
        //{
        //    Colors colorValue;
        //    bool isEnum = Enum.TryParse(data, out colorValue);
        //    return isEnum;
        //}

        private static bool IsValidNumber(string data)
        {
            int number;

            bool isNumber = Int32.TryParse(data, out number);
            return isNumber;
        }

        private bool IsNameValid(string userInputName)
        {
            return SearchParameters.ParamList.Any(paramInfo => paramInfo.Name == userInputName.ToLower());
        }

        private static class SearchParameters
        {
            public static List<ParamInfo> ParamList = new List<ParamInfo>
            {
                new ParamInfo {Name ="location", IsMandatory = true , ExpecteDataType = typeof(ulong) } ,
                new ParamInfo {Name ="service", IsMandatory = true  , ExpecteDataType = typeof(ServiceType)} ,
                new ParamInfo {Name ="start", IsMandatory = true  , ExpecteDataType = typeof(DateTimeOffset)} ,
                new ParamInfo {Name ="appointmentType", IsMandatory = true  , ExpecteDataType = typeof(AppointmentType)} ,
                new ParamInfo {Name ="status", IsOptional = true  , ExpecteDataType = typeof(string)} ,
                new ParamInfo {Name ="end", IsOptional = true  , ExpecteDataType = typeof(DateTimeOffset)} ,
                new ParamInfo {Name ="clinicianGender", IsOptional = true , ExpecteDataType = typeof(AdministrativeGender)}   ,
                new ParamInfo {Name ="_sort", IsForSorting = true , ExpecteDataType = typeof(string)},
                new ParamInfo {Name ="_count", IsForPaging = true , ExpecteDataType = typeof(uint)}
            };
        }
    }
}
相关问题
最新问题