如何在LINQ .select中选择整数的最后一位？

Question

我有这个LINQ选择：

 var extendedPhrases = phrases
            .Select(x => new ExtendedPhrase()
            {
                Ajlpt = x.Ajlpt,
                Bjlpt = x.Bjlpt,
                Created = x.Created // an int?
            });

如果我定义：

public int? CreatedLast { get; set; }

那么如何用x.Created的最后一位填充呢？

Answer 1

如果您要查找**Can not set int field com.example.domain.Company.cmpId to java.lang.Integer** Hibernate except foreign key of employee table cmp_id, should be primary key of company. But in your code cmpId is not primary key. @Column(name="company_id") private int cmpId; Please make that primary and check once. Edited:- 1. @OneToOne(fetch=FetchType.LAZY, mappedBy="company") private Employee employee; change to:- @OneToOne(fetch=FetchType.LAZY, mappedBy="company",optional=false) private Employee employee; 2. @OneToOne(fetch=FetchType.LAZY) @JoinColumn(name="cmp_id", referencedColumnName="company_id") private Company company; change to:- @OneToOne(fetch=FetchType.LAZY) @JoinColumn(name="cmp_id") private Company company; 属性的最后一位，请使用% operator，如下所示：

Created

Answer 2

首先要想到的是调用.ToString（）。Last（）：

var extendedPhrases = phrases
        .Select(x => new ExtendedPhrase()
        {
            Ajlpt = x.Ajlpt,
            Bjlpt = x.Bjlpt,
            Created = x.Created,
            CreatedLast = x.Created?.ToString().Last()
        });

如果您没有使用最新的闪亮C＃，则可以使用以下方式进行空保护：

var extendedPhrases = phrases
        .Select(x => new ExtendedPhrase()
        {
            Ajlpt = x.Ajlpt,
            Bjlpt = x.Bjlpt,
            Created = x.Created,
            CreatedLast = x.Created.HasValue ? x.Created.ToString().Last() : null
        });

将一些转换回int?作为练习留给读者。