C# 短小精悍的多重映射
我有一个目标:C# 短小精悍的多重映射,c#,dapper,C#,Dapper,我有一个目标: public class Species : IEntity<int> { public int Id { get; set; } public string Name { get; set; } public SpeciesCategory Category { get; set; } public WetlandIndicator WetlandIndicator { get; set; } } public class
public class Species : IEntity<int>
{
public int Id { get; set; }
public string Name { get; set; }
public SpeciesCategory Category { get; set; }
public WetlandIndicator WetlandIndicator { get; set; }
}
public class SpeciesCategory : IEntity<int>
{
public int Id { get; set; }
public string Name { get; set; }
}
public class WetlandIndicator : IEntity<string>
{
public string Id { get; set; }
public string Designation { get; set; }
public bool Status { get; set; }
}
我收到“确保使用多重映射时,确保使用splitOn
属性”。我是,但我仍然收到错误。所以我假设我有某种类型的使用错误或语法错误。持续出错的代码如下所示:
public async Task<IEnumerable<SpeciesDomain>> GetAllSpecies(string query) =>
await dbConnection.QueryAsync<Species, SpeciesCategory, WetlandIndicator, SpeciesDomain>(query, (species, speciesCategory, wetlandIndicator) =>
{
species.SpeciesCategory = speciesCategory;
species.WetlandIndicator = wetlandIndicator;
return species;
}, splitOn: "Id, Code");
公共异步任务GetAllSpecies(字符串查询)=>
等待dbConnection.QueryAsync(查询,(物种、物种类别、wetlandIndicator)=>
{
species.SpeciesCategory=物种类别;
物种。湿着陆指示器=湿着陆指示器;
返回物种;
},splitOn:“Id,Code”);
重要提示:默认情况下,Dapper使用Id,这就是为什么我将代码重命名为Id,但即使使用代码或重命名,我仍然会收到一个多重映射错误。看起来您只需要从splitOn中删除“代码”:“Id,代码”。您的查询将其重命名为“Id” Dapper还使用“Id”作为默认值,因此无需指定 Dapper能够通过假设来分割返回的行 您的Id列被命名为Id或Id。如果您的主键不同 或者要在Id以外的点拆分行,请使用 可选的splitOn参数 以下是验证的快速测试:
using (var conn = new SqlConnection(@"Data Source=.\sqlexpress;Integrated Security=true; Initial Catalog=foo"))
{
var result = conn.Query<Species, SpeciesCategory, WetlandIndicator, Species>(
"select Id = 11, Name = 'Foo', Id = 22, Name = 'Bar', Id = 33, Designation = 'House Cat' ",
(species, speciesCategory, wetlandIndicator) =>
{
species.Category = speciesCategory;
species.WetlandIndicator = wetlandIndicator;
return species;
}).First();
Assert.That(result.Id, Is.EqualTo(11));
Assert.That(result.Category.Id, Is.EqualTo(22));
Assert.That(result.Category.Name, Is.EqualTo("Bar"));
Assert.That(result.WetlandIndicator.Id, Is.EqualTo(33));
Assert.That(result.WetlandIndicator.Designation, Is.EqualTo("House Cat"));
}
使用(var conn=new SqlConnection(@“Data Source=。\sqlexpress;Integrated Security=true;Initial Catalog=foo”))
{
var结果=连接查询(
“选择Id=11,名称='Foo',Id=22,名称='Bar',Id=33,名称='House Cat'”,
(物种、物种类别、湿地指示器)=>
{
物种类别=物种类别;
物种。湿着陆指示器=湿着陆指示器;
返回物种;
}).First();
Assert.That(result.Id,Is.EqualTo(11));
Assert.That(result.Category.Id,Is.EqualTo(22));
Assert.That(result.Category.Name,Is.EqualTo(“Bar”);
Assert.That(result.WetlandIndicator.Id,Is.EqualTo(33));
断言(result.WetlandIndicator.Designation,Is.EqualTo(“家猫”));
}
按不同字段和类型划分的演示更新
public class Species
{
public int Id { get; set; }
public string Name { get; set; }
public SpeciesCategory Category { get; set; }
public WetlandIndicator WetlandIndicator { get; set; }
}
public class SpeciesCategory
{
public int Id { get; set; }
public string Name { get; set; }
}
public class WetlandIndicator
{
public string Code { get; set; }
public string Designation { get; set; }
public bool Status { get; set; }
}
using (var conn = new SqlConnection(@"Data Source=.\sqlexpress;Integrated Security=true; Initial Catalog=foo"))
{
var result = conn.Query<Species, SpeciesCategory, WetlandIndicator, Species>(
"select Id = 11, Name = 'Foo', Id = 22, Name = 'Bar', Code = 'X', Designation = 'House Cat' ",
(species, speciesCategory, wetlandIndicator) =>
{
species.Category = speciesCategory;
species.WetlandIndicator = wetlandIndicator;
return species;
}, splitOn: "Id, Code").First();
Assert.That(result.Id, Is.EqualTo(11));
Assert.That(result.Category.Id, Is.EqualTo(22));
Assert.That(result.Category.Name, Is.EqualTo("Bar"));
Assert.That(result.WetlandIndicator.Code, Is.EqualTo("X"));
Assert.That(result.WetlandIndicator.Designation, Is.EqualTo("House Cat"));
}
公共类物种
{
公共int Id{get;set;}
公共字符串名称{get;set;}
公共物种类别{get;set;}
公共湿着陆指示器湿着陆指示器{get;set;}
}
公共类物种类别
{
公共int Id{get;set;}
公共字符串名称{get;set;}
}
公共类湿着陆指示器
{
公共字符串代码{get;set;}
公共字符串名称{get;set;}
公共布尔状态{get;set;}
}
使用(var conn=new SqlConnection(@“数据源=。\sqlexpress;集成安全性=true;初始目录=foo”))
{
var结果=连接查询(
“选择Id=11,名称='Foo',Id=22,名称='Bar',代码='X',名称='House Cat'”,
(物种、物种类别、湿地指示器)=>
{
物种类别=物种类别;
物种。湿着陆指示器=湿着陆指示器;
返回物种;
},splitOn:“Id,Code”).First();
Assert.That(result.Id,Is.EqualTo(11));
Assert.That(result.Category.Id,Is.EqualTo(22));
Assert.That(result.Category.Name,Is.EqualTo(“Bar”);
Assert.That(result.WetlandIndicator.Code,Is.EqualTo(“X”));
断言(result.WetlandIndicator.Designation,Is.EqualTo(“家猫”));
}
因此,我找到了它失败的主要原因。Dapper不喜欢在int
和string
之间交替使用splitOn
参数。通过迫使所有国家统一起来,它起了作用。我注意到的另一点是,例如,如果您有一个名为code
的列,它镜像主键,但SQL没有设置为关系标识符,那么它也会出错
在这些问题得到纠正之后,它就没有问题了。只是为了向其他人澄清:如果使用不同数据类型的字段进行拆分,Dapper不会失败。我将更新我的演示答案。我需要澄清,如果您有字段:“代码”和一个名为“代码”的Id列问题。
public class Species
{
public int Id { get; set; }
public string Name { get; set; }
public SpeciesCategory Category { get; set; }
public WetlandIndicator WetlandIndicator { get; set; }
}
public class SpeciesCategory
{
public int Id { get; set; }
public string Name { get; set; }
}
public class WetlandIndicator
{
public string Code { get; set; }
public string Designation { get; set; }
public bool Status { get; set; }
}
using (var conn = new SqlConnection(@"Data Source=.\sqlexpress;Integrated Security=true; Initial Catalog=foo"))
{
var result = conn.Query<Species, SpeciesCategory, WetlandIndicator, Species>(
"select Id = 11, Name = 'Foo', Id = 22, Name = 'Bar', Code = 'X', Designation = 'House Cat' ",
(species, speciesCategory, wetlandIndicator) =>
{
species.Category = speciesCategory;
species.WetlandIndicator = wetlandIndicator;
return species;
}, splitOn: "Id, Code").First();
Assert.That(result.Id, Is.EqualTo(11));
Assert.That(result.Category.Id, Is.EqualTo(22));
Assert.That(result.Category.Name, Is.EqualTo("Bar"));
Assert.That(result.WetlandIndicator.Code, Is.EqualTo("X"));
Assert.That(result.WetlandIndicator.Designation, Is.EqualTo("House Cat"));
}