EF Core 3.1 不允许在 Enum 属性上进行包含搜索

Question

我正在尝试在我的 DbSet 中对 enum 属性进行包含搜索，而 EF Core 3.1 抛出以下错误

The LINQ expression 'DbSet .Where(d => d.Position.ToString().Contains("acc"))' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync()

实体：

public class DemoEntity
{
    [Key]
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public Position Position { get; set; }
}

枚举 - 位置：

public enum Position
{
    [Display(Name = "Accountant")]
    Accountant,
    [Display(Name = "Chief Executive Officer (CEO)")]
    ChiefExecutiveOfficer,
    [Display(Name = "Integration Specialist")]
    IntegrationSpecialist,
    [Display(Name = "Junior Technical Author")]
    JuniorTechnicalAuthor,
    [Display(Name = "Pre Sales Support")]
    PreSalesSupport,
    [Display(Name = "Sales Assistant")]
    SalesAssistant,
    [Display(Name = "Senior Javascript Developer")]
    SeniorJavascriptDeveloper,
    [Display(Name = "Software Engineer")]
    SoftwareEngineer
}

数据库上下文：

public class DemoDbContext : DbContext
{
    public DemoDbContext(DbContextOptions options)
        : base(options) { }

    public DbSet<DemoEntity> Demos { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder
            .Entity<DemoEntity>()
            .Property(e => e.Position)
            .HasConversion<string>();
    }
}

当我按如下方式查询 table 时，出现错误

try
{
    var test = await _context.Demos.Where(x => x.Position.ToString().Contains("acc")).ToListAsync();
}
catch (System.Exception e)
{
    //throw;
}

职位在我的数据库中属于 NVARCHAR(MAX) 类型。

这不可能吧？如果是这样，你能帮我解释一下吗？

Answer 1

此问题已记录在 efcore github repo 中，现在这里是解决方法。 enum 属性需要转换为 object 然后转换为 string

var test = await _context.Demos.Where(x => ((string) object)x.Position).Contains("acc")).ToListAsync();

希望这对那里的人有所帮助。

EF Core 3.1 不允许在 Enum 属性上进行包含搜索

EF Core 3.1 does not allow Contains search on Enum property

c#

enums

entity-framework-core

entity-framework-core-3.1

EF Core 3.1 不允许在 Enum 属性 上进行包含搜索

EF Core 3.1 does not allow Contains search on Enum property

c#

enums

entity-framework-core

entity-framework-core-3.1

EF Core 3.1 不允许在 Enum 属性上进行包含搜索