Question

我有这个viewmodel

public class TipoProyectoViewModel
{      
    public string Category{ get; set; }
    public IEnumerable<ProjectType> Type{ get; set; }
}

我按类型

订购了所有项目

var category = _dbContext.Categoria 
    .Include( c => c.TipoProyecto )
    .Where( c => c.CategoryId == CategoryId )
    .GroupBy( e => e.CategoryName )
    .Select( e => new TipoProyectoViewModel() {
        Category = e.Key,
        Tipo = e.SelectMany( p => p.ProjectType )
    } )
    .FirstOrDefault();

此代码返回类似

的内容

Home //project category as string in my viewmodel
{
    Ienmuerable1
    Ienumerable2 //a list of ProjectType
    .....
}

Home //project category as string
{
    Ienmuerable1
    Ienumerable2 //a list of ProjectType
    .....
}

现在我想在我的viewmodel中添加一个新属性，并从数据库中获取它

public class TipoProyectoViewModel
{   
    public string Glyphicons { get; set; }   
    public string Category { get; set; }
    public IEnumerable<ProjectType> Type { get; set; }
}

Glyphicons来自我的类别表

public class Categoria
{
    [Required]
    public Guid Id { get; set; }
    public string CategoryName { get; set; }
    public ICollection<ProjectType> ProjectType { get; set; }
    public string Glyphicons { get; set; }  <<<<<glyphicons
}

我应该如何修改实体框架查询？

var category = _dbContext.Categoria
    .Include( c => c.TipoProyecto )
    .Where( c => c.CategoryId == CategoryId )
    .GroupBy( e => e.CategoryName )
    .Select( e => new TipoProyectoViewModel() {
        Category = e.Key,
        glyp=...,
        Tipo = e.SelectMany( p => p.ProjectType )
    } )
    .FirstOrDefault();

Answer 1

ViewModels与您的数据库实体类型正交。

您应该直接创建ViewModel对象并在查询之外填充它，如下所示：

public IActionResult Get()
{
    TipoProyectoViewModel viewModel = new TipoProyectoViewModel();

    using( var dbContext = ... )
    {
        var catgoryGroup = dbContext.Categoria
            .Include( c => c.TipoProyecto )
            .Where( c => c.CategoryId == CategoryId )
            .GroupBy( e => e.CategoryName )
            .FirstOrDefault();

        viewModel.Category = catgoryGroup.Key;
        viewModel.Tipo = categoryGroup
            .SelectMany( p => p.ProjectType )
            .ToList(); // Always call ToList() because you should never pass an IQueryable to your View!

        viewModel.Glyphicons = dbContext
            .Select( /* your query to get data for this property */ );
    }

    return this.View( viewModel );
}

向Entity Framework查询添加新字段

1 个答案: