Question

EntityFrameworkCore：1.1.0

我总是得到一个带有＆＃34;简单＆＃34;的InvalidOperationException。 linq查询并无法弄清楚原因。它适用于标签，但不适用于各国。

我尝试执行以下查询：

var tags = new string[]{"guid1", "guid2"};
var countries = new int[]{1, 2};
var test = _dbContext.Articles
            .Include(a => a.Countries).ThenInclude(c => c.Country)
            .Include(a => a.Tags)
            .Where(article => article.Tags.Any(t => tags.Contains(t.Tag.Id)) &&
                              article.Countries.Any(c2 => countries.Contains(c2.Country.Id)))
           .ToList();

并始终获得以下异常：

变量＆c; country＆＃39;类型＆＃39;国家＆＃39;引用范围＆＃39;＆＃39;，但未定义

使用以下实体：

public class Article
{
    /// <summary>
    /// Unique ID of the article
    /// </summary>
    [Required]
    public Guid Id { get; set; }

    /// <summary>
    /// Article type
    /// </summary>
    [Required]
    public ArticleTypes Type { get; set; }

    /// <summary>
    /// Gets or sets the article tags.
    /// </summary>
    /// <value>
    /// The article tags.
    /// </value>
    public ICollection<ArticleTag> Tags { get; set; }

    /// <summary>
    /// Gets or sets the countries.
    /// </summary>
    /// <value>
    /// The countries.
    /// </value>
    public ICollection<ArticleCountry> Countries { get; set; }
}

public class ArticleCountry
{
    /// <summary>
    /// Gets or sets the identifier.
    /// </summary>
    /// <value>
    /// The identifier.
    /// </value>
    public Guid Id { get; set; }

    /// <summary>
    /// Gets or sets the country.
    /// </summary>
    /// <value>
    /// The country.
    /// </value>
    public Country Country { get; set; }

    /// <summary>
    /// 
    /// </summary>
    public int Position { get; set; }
}

public class Country
{
    /// <summary>
    /// Gets or sets the identifier.
    /// </summary>
    /// <value>
    /// The identifier.
    /// </value>
    [JsonIgnore]
    public int Id { get; set; }

    /// <summary>
    /// Unique country code
    /// </summary>
    [JsonProperty("key")]
    [Required]
    [StringLength(2)]
    public string Code { get; set; }

    /// <summary>
    /// Country name
    /// </summary>
    [JsonProperty("name")]
    [Required]
    public string Name { get; set; }
}

public class Tag
{
    /// <summary>
    /// Tag unique key
    /// </summary>
    [JsonProperty("key")]
    [Required]
    public Guid Id { get; set; }

    /// <summary>
    /// Tag name
    /// </summary>
    [JsonProperty("name")]
    [Required]
    public string Name { get; set; }
}

public class ArticleTag
{
    /// <summary>
    /// Gets or sets the identifier.
    /// </summary>
    /// <value>
    /// The identifier.
    /// </value>
    [Required]
    public Guid Id { get; set; }

    /// <summary>
    /// Gets or sets the order.
    /// </summary>
    /// <value>
    /// The order.
    /// </value>
    [Required]
    public int Position { get; set; }

    /// <summary>
    /// Gets or sets the tag.
    /// </summary>
    /// <value>
    /// The tag.
    /// </value>
    [Required]
    public Tag Tag { get; set; }
}

我还可以在控制台中看到以下警告：

警告：Microsoft.EntityFrameworkCore.Query.Internal.SqlServerQueryCompilationContextFactory [8] LINQ表达式＆＃39; {__ countries_1 =＆gt;含有（转换（（[c2.Country] .ID））？）}＆＃39;无法翻译，将在本地进行评估。要配置此警告，请使用DbContextOptionsBuilder.ConfigureWarnings API（事件ID＆＃39; RelationalEventId.QueryClientEvaluationWarning＆＃39;）。重写DbContext.OnConfiguring方法或在应用程序服务提供程序上使用AddDbContext时，可以使用ConfigureWarnings。

Answer 1

我通过在ArticleCountry.Country属性

中添加[必需]来修复此问题

{ defer; panic(); recover() }

似乎连接不喜欢可以为空的FK

EntityFrameworkCore Linq错误：变量＆＃39; country.Country＆＃39;类型＆＃39;国家＆＃39;从范围＆＃39;＆＃39;引用，但未定义

1 个答案: