c# linq 从 linq 返回一个多维数组 [英] c# linq return a multidimensional array from linq
问题描述
我想返回一个多维数组以保存在会话中,但不确定如何从 linq 返回它:
I want to return a multidimensional array to hold in a session but not sure how to return it from linq:
public string[] GetCountryAndManufacturerForUser(int userId)
{
var array = (from xx in _er.UserRoles
join xy in _er.Countries on xx.CountryId equals xy.Id
join xz in _er.Manufacturers on xx.ManufacturerId equals xz.Id
where xx.UserId == userId
select new { xy.Name, xz.Description }).ToArray();
return??
}
我知道我在这里做错了什么,只是不确定是什么.
i know i m doing something wrong here just not sure what.
需要返回以下字段 - xy.Name, xz.Description
The following fields need to be returned - xy.Name, xz.Description
喜欢:
{ "1", "aaa" },
{ "2", "bbb" }
我已经尝试了下面的示例,但他们还没有达到我需要的位置 - 我认为以下内容应该可行:
I have tried the example below and they haven t quite got to where i need to be - i thought something like the following should work:
/// <summary>
///
/// </summary>
/// <param name="userId"></param>
/// <returns></returns>
public string[,] GetCountryAndManufacturerForUser(int userId)
{
var array = (from xx in _er.UserRoles
join xy in _er.Countries on xx.CountryId equals xy.Id
join xz in _er.Manufacturers on xx.ManufacturerId equals xz.Id
where xx.UserId == userId
select new { xy.Name, xz.Description }).ToArray();
return array;
}
但它抱怨返回数组;
我得到的最接近的是以下内容:
The closest i ve got is the following:
/// <summary>
///
/// </summary>
/// <param name="userId"></param>
/// <returns></returns>
public string[][] GetCountryAndManufacturerForUser(int userId)
{
//var array = (from xx in _er.UserRoles
// join xy in _er.Countries on xx.CountryId equals xy.Id
// join xz in _er.Manufacturers on xx.ManufacturerId equals xz.Id
// where xx.UserId == userId
// select new { xy.Name, xz.Description }).ToArray();
var countryArray = (from xx in _er.UserRoles
join xy in _er.Countries on xx.CountryId equals xy.Id
join xz in _er.Manufacturers on xx.ManufacturerId equals xz.Id
where xx.UserId == userId
select xy.Name).ToArray();
var manufacturerArray = (from xx in _er.UserRoles
join xy in _er.Countries on xx.CountryId equals xy.Id
join xz in _er.Manufacturers on xx.ManufacturerId equals xz.Id
where xx.UserId == userId
select xz.Description).ToArray();
// return array;
return new string[][] { countryArray, manufacturerArray };
}
但这返回两个数组:
var userManuCountry = _userRoleRepository.GetCountryAndManufacturerForUser(u.Id);
userManuCountry {string[2][]} string[][]
[0] {string[6]} string[]
[0] "Germany" string
[1] "France" string
[2] "United Kingdom" string
[3] "Netherlands" string
[4] "United States" string
[5] "United Kingdom" string
- [1] {string[6]} string[]
[0] "Dove" string
[1] "Dove" string
[2] "Dove" string
[3] "Dove" string
[4] "Dove" string
[5] "Sure" string
推荐答案
锯齿状数组.
public string[][] GetCountryAndManufacturerForUser(int userId)
{
return (from xx in _er.UserRoles
join xy in _er.Countries on xx.CountryId equals xy.Id
join xz in _er.Manufacturers on xx.ManufacturerId equals xz.Id
where xx.UserId == userId
select new string[]{ xy.Name, xz.Description }).ToArray();
}
多维数组
public string[,] GetCountryAndManufacturerForUser(int userId)
{
var array =(from xx in _er.UserRoles
join xy in _er.Countries on xx.CountryId equals xy.Id
join xz in _er.Manufacturers on xx.ManufacturerId equals xz.Id
where xx.UserId == userId
select new List<string>{ xy.Name, xz.Description }).ToArray();
return CreateRectangularArray(array);
}
static T[,] CreateRectangularArray<T>(IList<T>[] arrays)
{
// TODO: Validation and special-casing for arrays.Count == 0
int minorLength = arrays[0].Count();
T[,] ret = new T[arrays.Length, minorLength];
for (int i = 0; i < arrays.Length; i++)
{
var array = arrays[i];
if (array.Count != minorLength)
{
throw new ArgumentException
("All arrays must be the same length");
}
for (int j = 0; j < minorLength; j++)
{
ret[i, j] = array[j];
}
}
return ret;
}
上述方法取自 John skeet 对问题的回答之一 如何将数组列表转换为多维数组
Above method taken from one of answer by John skeet for the Question How to convert list of arrays into a multidimensional array
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