使用QueryMultiple的Dapper Multi Mapping

Question

我有一个返回多个结果集的存储过程.我用小巧玲珑执行这个.

其中一个结果集是Person JOIN Checks,其中Person可以有很多Checks.

最终目标是拥有具有检查对象集合的不同人物对象.

QueryMutliple给了我一个Sqlmapper.GridReader.我看到一个重载SqlMapper.GridReader.Read()需要一个Func<TFirst, TSecond, TReturn>.

有一个如何使用它的例子？

Answer 1

以下是我如何使用它:

var q = _sqlConnection.QueryMultiple("MySproc",
                                     myParams,
                                     commandType: CommandType.StoredProcedure);
var set1 = q.Read<Set1Type>();

var set2Func = new Func<Person, Check, Person>((p, c) => {
    p.CheckAlert = c;
    return p;
});

var set2 = q.Read(set2Func, "CheckId")
            .GroupBy(x => x.PersonId)
            .Select(x => {
                var person = x.First();
                person.Checks = x.Select(p => p.Check).ToArray();
                person.Check = null; // i really don't like this
                return person;
            })
            .ToArray();

正如评论所说,我不喜欢Person对象上不需要的check属性.

我仍然喜欢听到更好的方法.

Answer 2

这是我使用的解决方案的一个版本.我使用继承层次而不是将属性设置为null来解决Ronnie在他的回答中提出的问题,但它完全相同.

这是SQL:用户拥有项目和集合,项目可以在集合中.

CREATE TABLE Users
(id UNIQUEIDENTIFIER DEFAULT (NEWID()) NOT NULL,
name NVARCHAR (MAX) NULL,
email NVARCHAR (128) NULL,
PRIMARY KEY (id))

CREATE TABLE Items
(id UNIQUEIDENTIFIER DEFAULT (NEWID()) NOT NULL,
userId UNIQUEIDENTIFIER NOT NULL,
name NVARCHAR (MAX) NULL,
description NVARCHAR (MAX) NULL,
PRIMARY KEY (id),
FOREIGN KEY (userId) REFERENCES Users (id))

CREATE TABLE Collections
(id UNIQUEIDENTIFIER DEFAULT (NEWID()) NOT NULL,
userId UNIQUEIDENTIFIER NOT NULL,
name NVARCHAR (MAX) NULL,
layoutSettings NVARCHAR (MAX) NULL,
PRIMARY KEY (id),
FOREIGN KEY (userId) REFERENCES Users (id))

CREATE TABLE CollectedItems
(itemId UNIQUEIDENTIFIER NOT NULL,
collectionId  UNIQUEIDENTIFIER NOT NULL,
PRIMARY KEY CLUSTERED (itemId, collectionId),
FOREIGN KEY (itemId) REFERENCES Items (id),
FOREIGN KEY (collectionId) REFERENCES Collections (id))

现在是数据模型类.为了处理具有多个查询的Dapper多映射,集合比我预期的要复杂一些.

public class User
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public string Email { get; set; }
    public List<Item> Items { get; set; }
    public List<Collection> Collections { get; set; }
}

public class Item
{
    public Guid Id { get; set; }
    public Guid UserId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
}

public class CoreCollection
{
    public Guid Id { get; set; }
    public Guid UserId { get; set; }
    public string Name { get; set; }
    public string LayoutSettings { get; set; }
}

public class PartialDataCollection : CoreCollection
{
    public Guid ItemId { get; set; }
}

public class Collection : CoreCollection
{
    public List<Guid> ItemIds { get; set; }
}

public class CollectedItem
{
    public Guid ItemId { get; set; }
    public Guid CollectionId { get; set; }
    public DateTime CreatedAt { get; set; }
}

最后,我们有控制器方法,它使用带有多个查询的Dapper多映射

[Route("GetUser/{id}")]
public User GetUser(Guid id)
{
    var sql = @"SELECT * FROM Users WHERE id = @id
                SELECT * FROM Items WHERE userId = @id
                SELECT * FROM Collections 
                    LEFT OUTER JOIN CollectedItems ON Collections.id = CollectedItems.collectionId  
                    WHERE userId = @id";
    using (var connection = new SqlConnection(ConnectionString))
    {
        var multi = connection.QueryMultiple(sql, new { id = id });
        var user = multi.Read<User>().Single();
        var items = multi.Read<Item>().ToList();
        var partialDataCollections = multi.Read<PartialDataCollection, CollectedItem, PartialDataCollection>(AddCollectedItem, splitOn: "itemId").ToList();

        user.Items = items;

        user.Collections = partialDataCollections.GroupBy(
            pdc => pdc.Id,
            (key, group) => new Collection
            {
                Id = key,
                UserId = group.First().UserId,
                Name = group.First().Name,
                LayoutSettings = group.First().LayoutSettings,
                ItemIds = group.Select(groupMember => groupMember.ItemId).ToList()
            }).ToList();

        return user;
    }
}

private PartialDataCollection AddCollectedItem(PartialDataCollection collection, CollectedItem collectedItem)
{
    if (collection != null && collectedItem != null)
    {
        collection.ItemId = collectedItem.ItemId;
    }
    return collection;
}

当罗尼是担心设置person.Check = null在他的回答我担心从添加类在我的答案额外的复杂性PartialDataCollection,以我的模型.但我无法看到一个简单的方法.

(注意,我已将此作为Dapper GitHub项目的问题提出.)