[英]Joining or Including multiple tables with Entity Framework Core LINQ to Entities - One to Many and then Many to One
使用 Entity Framework Core 進行設置，EF 以對我有意義的方式遷移了數據庫，現在我想從數據庫中檢索數據並返回一個成員列表，其中包含一個包含全名的職位列表，這樣我就可以循環顯示根據需要的記錄列表。
每個會員可能很少持有超過一個 position。每個 Position 可能由多個會員持有。
例如3個會員可能只有“會員”的Position，3個會員持有“單位負責人”，1個窮會員持有“單位行政官”和“單位培訓官”的position。
我嘗試使用 Include、IncludeThen，但這似乎是一對多、一對多類型的嵌套。 加入和 LINQ 到實體、表/實體拆分，我正在更深入地研究信息過載和過度思考。
我如何返回完整的成員列表、他們的職位列表和他們擔任的職位名稱？
到目前為止我的嘗試
public class MembersDB : IMembersDB
{
private readonly ApplicationDbContext appDbContext;
public MembersDB(ApplicationDbContext appDbContext)
{
this.appDbContext = appDbContext;
}
public async Task<IEnumerable<Member>> GetMembers()
{
/*var ListOfMembers = appDbContext.Members
.Select(m => new
{
Member = m,
PositionHeld = m.PositionsHeld,
Unit = m.Unit
});
return await ListOfMembers.ToListAsync(); //error - since not a <IEnumerable<Member>> type*/
return await appDbContext.Members.ToListAsync(); //Missing Position Name
}
}
修剪過的模型
public class Member
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public string MemberId { get; set; }
[Required]
public string FirstName { get; set; }
[Required]
public ICollection<PositionsHeld> PositionsHeld { get; set; }
}
[Index(nameof(PositionDisplayName), IsUnique = true)]
public class Position
{
[Key]
public int PositionId { get; set; }
[Required]
public string PositionDisplayName { get; set; }
public string PositionFullName { get; set; }
[Required]
public int PositionRank { get; set; }
public ICollection<PositionsHeld> PositionsHelds {get; set;}
}
public class PositionsHeld
{
[Key]
public int PositionsHeldId { get; set; }
public int PositionId { get; set; }
public Position Position { get; set; }
public string MemberId { get; set; }
public Member Member { get; set; }
}
這是一個使用獨立宣言簽署者的解決方案。
輸出的前 10 行：
Adams, John [Lawyer]
Adams, Samuel [Merchant]
Bartlett, Josiah [Physician]
Braxton, Carter [Plantation Owner]
Carroll, Charles [Merchant,Plantation Owner]
Chase, Samuel [Lawyer]
Clark, Abraham [Lawyer,Surveyer]
Clymer, George [Merchant]
Ellery, William [Lawyer,Merchant]
Floyd, William [Land Speculator]
這是代碼
void Main()
{
var members = GetMembers();
var positions = GetPositions();
var positionsHeld = GetPositionsHeld();
var summary = positionsHeld
.Join(
positions,
ph => ph.PositionId,
p => p.PositionId,
(ph, p) => new { PositionHeld = ph, Position = p })
.Join(
members,
ph => ph.PositionHeld.MemberId,
m => m.MemberId,
(ph, m) => new { Member = m, Position = ph.Position })
.GroupBy(x => x.Member)
.Select(x => new { x.Key.LastName, x.Key.FirstName, Positions = string.Join(",", x.Select(h => h.Position.PositionFullName).ToList())});
foreach (var line in summary)
{
Console.WriteLine($"{line.LastName}, {line.FirstName} [{line.Positions}]");
}
}
public IEnumerable<Member> GetMembers()
{
return new List<Member>
{
new Member { MemberId = "10", FirstName = "John", LastName = "Adams" },
new Member { MemberId = "11", FirstName = "Samuel", LastName = "Adams" },
new Member { MemberId = "12", FirstName = "Josiah", LastName = "Bartlett" },
new Member { MemberId = "13", FirstName = "Carter", LastName = "Braxton" },
new Member { MemberId = "14", FirstName = "Charles", LastName = "Carroll" },
new Member { MemberId = "15", FirstName = "Samuel", LastName = "Chase" },
new Member { MemberId = "16", FirstName = "Abraham", LastName = "Clark" },
new Member { MemberId = "17", FirstName = "George", LastName = "Clymer" },
new Member { MemberId = "18", FirstName = "William", LastName = "Ellery" },
new Member { MemberId = "19", FirstName = "William", LastName = "Floyd" },
new Member { MemberId = "20", FirstName = "Benjamin", LastName = "Franklin" },
new Member { MemberId = "21", FirstName = "Elbridge", LastName = "Gerry" },
new Member { MemberId = "22", FirstName = "Button", LastName = "Gwinnett" },
new Member { MemberId = "23", FirstName = "Lyman", LastName = "Hall" },
new Member { MemberId = "24", FirstName = "John", LastName = "Hancock" },
new Member { MemberId = "25", FirstName = "Benjamin", LastName = "Harrison" },
new Member { MemberId = "26", FirstName = "John", LastName = "Hart" },
new Member { MemberId = "27", FirstName = "Joseph", LastName = "Hewes" },
new Member { MemberId = "28", FirstName = "Thomas", LastName = "Heyward" },
new Member { MemberId = "29", FirstName = "William", LastName = "Hooper" },
new Member { MemberId = "30", FirstName = "Stephen", LastName = "Hopkins" },
new Member { MemberId = "31", FirstName = "Francis", LastName = "Hopkinson" },
new Member { MemberId = "32", FirstName = "Samuel", LastName = "Huntington" },
new Member { MemberId = "33", FirstName = "Thomas", LastName = "Jefferson" },
new Member { MemberId = "34", FirstName = "Francis", LastName = "Lee" },
new Member { MemberId = "35", FirstName = "Richard", LastName = "Lee" },
new Member { MemberId = "36", FirstName = "Francis", LastName = "Lewis" },
new Member { MemberId = "37", FirstName = "Philip", LastName = "Livingston" },
new Member { MemberId = "38", FirstName = "Thomas", LastName = "Lynch" },
new Member { MemberId = "39", FirstName = "Thomas", LastName = "McKean" },
new Member { MemberId = "40", FirstName = "Arthur", LastName = "Middleton" },
new Member { MemberId = "41", FirstName = "Lewis", LastName = "Morris" },
new Member { MemberId = "42", FirstName = "Robert", LastName = "Morris" },
new Member { MemberId = "43", FirstName = "John", LastName = "Morton" },
new Member { MemberId = "44", FirstName = "Thomas", LastName = "Nelson" },
new Member { MemberId = "45", FirstName = "William", LastName = "Paca" },
new Member { MemberId = "46", FirstName = "Robert", LastName = "Paine" },
new Member { MemberId = "47", FirstName = "John", LastName = "Penn" },
new Member { MemberId = "48", FirstName = "George", LastName = "Read" },
new Member { MemberId = "49", FirstName = "Ceasar", LastName = "Rodney" },
new Member { MemberId = "50", FirstName = "George", LastName = "Ross" },
new Member { MemberId = "51", FirstName = "Benjamin", LastName = "Rush" },
new Member { MemberId = "52", FirstName = "Edward", LastName = "Rutledge" },
new Member { MemberId = "53", FirstName = "Roger", LastName = "Sherman" },
new Member { MemberId = "54", FirstName = "James", LastName = "Smith" },
new Member { MemberId = "55", FirstName = "Richard", LastName = "Stockton" },
new Member { MemberId = "56", FirstName = "Thomas", LastName = "Stone" },
new Member { MemberId = "57", FirstName = "George", LastName = "Taylor" },
new Member { MemberId = "58", FirstName = "Matthew", LastName = "Thornton" },
new Member { MemberId = "59", FirstName = "George", LastName = "Walton" },
new Member { MemberId = "60", FirstName = "William", LastName = "Whipple" },
new Member { MemberId = "61", FirstName = "William", LastName = "Williams" },
new Member { MemberId = "62", FirstName = "James", LastName = "Wilson" },
new Member { MemberId = "63", FirstName = "John", LastName = "Witherspoon" },
new Member { MemberId = "64", FirstName = "Oliver", LastName = "Wolcott" },
new Member { MemberId = "65", FirstName = "George", LastName = "Wythe" }
};
}
public IEnumerable<Position> GetPositions()
{
return new List<Position>
{
new Position { PositionId = 10, PositionRank = 110, PositionDisplayName = "FA", PositionFullName = "Farmer" },
new Position { PositionId = 11, PositionRank = 111, PositionDisplayName = "LO", PositionFullName = "Land Owner" },
new Position { PositionId = 12, PositionRank = 112, PositionDisplayName = "LS", PositionFullName = "Land Speculator" },
new Position { PositionId = 13, PositionRank = 113, PositionDisplayName = "LA", PositionFullName = "Lawyer" },
new Position { PositionId = 14, PositionRank = 114, PositionDisplayName = "ME", PositionFullName = "Merchant" },
new Position { PositionId = 15, PositionRank = 115, PositionDisplayName = "MO", PositionFullName = "Military Officer" },
new Position { PositionId = 16, PositionRank = 116, PositionDisplayName = "MI", PositionFullName = "Minister" },
new Position { PositionId = 17, PositionRank = 117, PositionDisplayName = "MU", PositionFullName = "Musician" },
new Position { PositionId = 18, PositionRank = 118, PositionDisplayName = "PH", PositionFullName = "Physician" },
new Position { PositionId = 19, PositionRank = 119, PositionDisplayName = "PO", PositionFullName = "Plantation Owner" },
new Position { PositionId = 20, PositionRank = 120, PositionDisplayName = "SC", PositionFullName = "Scientist" },
new Position { PositionId = 21, PositionRank = 121, PositionDisplayName = "SU", PositionFullName = "Surveyer" },
new Position { PositionId = 22, PositionRank = 122, PositionDisplayName = "PR", PositionFullName = "Printer" }
};
}
public IEnumerable<PositionsHeld> GetPositionsHeld()
{
return new List<PositionsHeld>
{
new PositionsHeld { PositionsHeldId = 10, MemberId = "10", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 11, MemberId = "11", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 12, MemberId = "12", PositionId = 18 },
new PositionsHeld { PositionsHeldId = 13, MemberId = "13", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 14, MemberId = "14", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 15, MemberId = "14", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 16, MemberId = "15", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 17, MemberId = "16", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 18, MemberId = "16", PositionId = 21 },
new PositionsHeld { PositionsHeldId = 19, MemberId = "17", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 20, MemberId = "18", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 21, MemberId = "18", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 22, MemberId = "19", PositionId = 12 },
new PositionsHeld { PositionsHeldId = 23, MemberId = "20", PositionId = 20 },
new PositionsHeld { PositionsHeldId = 24, MemberId = "20", PositionId = 22 },
new PositionsHeld { PositionsHeldId = 25, MemberId = "21", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 26, MemberId = "22", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 27, MemberId = "22", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 28, MemberId = "23", PositionId = 18 },
new PositionsHeld { PositionsHeldId = 29, MemberId = "23", PositionId = 16 },
new PositionsHeld { PositionsHeldId = 30, MemberId = "24", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 31, MemberId = "25", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 32, MemberId = "25", PositionId = 10 },
new PositionsHeld { PositionsHeldId = 33, MemberId = "26", PositionId = 11 },
new PositionsHeld { PositionsHeldId = 34, MemberId = "27", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 35, MemberId = "28", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 36, MemberId = "28", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 37, MemberId = "29", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 38, MemberId = "30", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 39, MemberId = "31", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 40, MemberId = "31", PositionId = 17 },
new PositionsHeld { PositionsHeldId = 41, MemberId = "32", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 42, MemberId = "33", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 43, MemberId = "33", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 44, MemberId = "33", PositionId = 20 },
new PositionsHeld { PositionsHeldId = 45, MemberId = "34", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 46, MemberId = "35", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 47, MemberId = "35", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 48, MemberId = "36", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 49, MemberId = "37", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 50, MemberId = "38", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 51, MemberId = "39", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 52, MemberId = "40", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 53, MemberId = "41", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 54, MemberId = "42", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 55, MemberId = "42", PositionId = 12 },
new PositionsHeld { PositionsHeldId = 56, MemberId = "43", PositionId = 10 },
new PositionsHeld { PositionsHeldId = 57, MemberId = "44", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 58, MemberId = "44", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 59, MemberId = "45", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 60, MemberId = "45", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 61, MemberId = "46", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 62, MemberId = "46", PositionId = 20 },
new PositionsHeld { PositionsHeldId = 63, MemberId = "47", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 64, MemberId = "48", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 65, MemberId = "49", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 66, MemberId = "49", PositionId = 15 },
new PositionsHeld { PositionsHeldId = 67, MemberId = "50", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 68, MemberId = "51", PositionId = 18 },
new PositionsHeld { PositionsHeldId = 69, MemberId = "52", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 70, MemberId = "52", PositionId = 19 },
new PositionsHeld { PositionsHeldId = 71, MemberId = "53", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 72, MemberId = "54", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 73, MemberId = "55", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 74, MemberId = "56", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 75, MemberId = "57", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 76, MemberId = "58", PositionId = 18 },
new PositionsHeld { PositionsHeldId = 77, MemberId = "59", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 78, MemberId = "60", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 79, MemberId = "61", PositionId = 14 },
new PositionsHeld { PositionsHeldId = 80, MemberId = "62", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 81, MemberId = "63", PositionId = 16 },
new PositionsHeld { PositionsHeldId = 82, MemberId = "64", PositionId = 13 },
new PositionsHeld { PositionsHeldId = 83, MemberId = "65", PositionId = 13 }
};
}
public class Member
{
public string MemberId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
public class Position
{
public int PositionId { get; set; }
public string PositionDisplayName { get; set; }
public string PositionFullName { get; set; }
public int PositionRank { get; set; }
}
public class PositionsHeld
{
public int PositionsHeldId { get; set; }
public int PositionId { get; set; }
public string MemberId { get; set; }
}
首先在實體框架代碼中連接具有一對多關系的兩個表
[英]Joining two tables with one to many relatipnship in entity framework code first
在實體框架核心中使用一對多關系更新連接的實體
[英]Updating connected entities with one-to-many relationships in entity framework core
Linq to實體（最新實體框架）獲得多對多和一對多關系
[英]Linq to entities(latest entity framework) get many to many and one to many relation
實體框架核心 - 兩個實體之間的多個一對多關系
[英]Entity Framework Core - Multiple one-to-many relationships between two entities
在LINQ .NET CORE中包含一對多或多對多的屬性
[英]Including properties of a one to many or many to many in LINQ .NET CORE
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