Javascript getJSON函数，查询linq返回的列表；“未定义”；

我实际上是想了解一点ASP.NETWebAPI。我想查询ArtistController类中包含的艺术家列表

这是前端的屏幕截图

这是我的控制器

public class ArtistsController : ApiController
{
    Artist[] artists = new Artist[]
    {
        new Artist { Name = "Metallica",Id ="65f4f0c5-ef9e-490c-aee3-909e7ae6b2ab",Country ="US",Aliases ="Metalica" },
        new Artist { Name = "Lady Gaga",Id ="650e7db6-b795-4eb5-a702-5ea2fc46c848",Country ="US",Aliases ="Lady Ga Ga,Stefani Joanne Angelina Germanotta" },
        new Artist { Name = "Mumford & Sons",Id ="c44e9c22-ef82-4a77-9bcd-af6c958446d6",Country ="GB",Aliases ="" },
        new Artist { Name = "Mott the Hoople",Id ="435f1441-0f43-479d-92db-a506449a686b",Country ="GB",Aliases ="Mott The Hoppie,Mott The Hopple" },
        new Artist { Name = "Megadeth",Id ="a9044915-8be3-4c7e-b11f-9e2d2ea0a91e",Country ="US",Aliases ="Megadeath" },
        new Artist { Name = "John Coltrane",Id ="b625448e-bf4a-41c3-a421-72ad46cdb831",Country ="US",Aliases ="John Coltraine,John William Coltrane" }
    }
    };

    public IEnumerable<Artist> GetAllArtists()
    {
        return artists;
    }

    public IHttpActionResult GetArtist(string name)
    {
        //IEnumerable<Artist> ArtistQuery = (from Artist in artists
        //                                  where Artist.Name.Contains(name)
        //                                  select Artist).ToList();
        IEnumerable<Artist> ArtistQuery = from Artist in artists
                                          where Artist.Name.Contains(name)
                                          select Artist;
        if (ArtistQuery == null)
        {
            return NotFound();
        }
        return Ok(ArtistQuery);
    }
}

下面是WEAPI配置

public static void Register(HttpConfiguration config) { 
    // Web API configuration and services // Web API routes 
    config.MapHttpAttributeRoutes(); 
    config.Routes.MapHttpRoute( 
            name: "DefaultApi", 
            routeTemplate: "api/{controller}/{id}", 
            defaults: new { id = RouteParameter.Optional } 
    ); 
}

我收到一个错误“未定义”“未定义”

后端没有编译错误

Chrome控制台中也没有javascript错误

---

谢谢你的帮助

您的

formatItem

的javascript需要一个项目

Artist

 function formatItem(item) { return item.Name + ' ' + item.Country; }

但是您的

GetArtist

正在返回一个

IEnumerable

，这将解释为什么您会看到

undefined-undefined

要么从

GetArtist

public IHttpActionResult GetArtist(string name) {       
    IEnumerable<Artist> ArtistQuery = from Artist in artists
                                      where Artist.Name.Contains(name)
                                      select Artist;
    if (ArtistQuery.Count() == 0) {
        return NotFound();
    }
    return Ok(ArtistQuery.First());
}

---

formatItem（数据）

有什么作用？有函数formatItem（item）{return item.Name+''+item.Country；}如果您使用Fiddler调用API端点with Postman，它会将输出显示为“艺术家名称”“国家”，您从API返回了有效的结果吗？jquery.getJson可以工作并发送所有艺术家，如下所示：var uri='API/artists'$（document）.ready（函数（）{//发送AJAX请求$.getJSON（uri）.done（函数（数据）{//成功时，“数据”包含艺术家列表。$。每个（数据、函数（键、项）{//为产品添加列表项。$（“

”，{text:formatItem（项）}）。附录（$（“#艺术家”）); }); }); });当我在《邮递员》中这样做时，我正确地得到了JSON格式的艺术家列表。[{“名称”：“Metallica”，“Id”：“65f4f0c5-ef9e-490c-aee3-909e7ae6b2ab”，“国家”：“美国”，“别名”：“Metalica”}，…]如果我从ur代码执行此操作，“var artist=data[0]”；它将只返回列表中的第一项“Metallica US”。我怎样才能找到所有与名字匹配的艺术家？使用正则表达式？？现在它显示所有的名称：）为了让它工作，它缺少了一个“）”。给你。完成（函数（数据）{if（数据）{$.each（数据，函数（键，项）{//将找到的美工人员的列表项添加到美工人员。$（“

”，{text:formatItem（项）}）。附录（$（“#美工人员”）；}）如果它显示全部，则意味着它正在点击

GetAllArtists

。您是如何配置路由的。更新您的问题以显示apipublic静态无效寄存器（HttpConfiguration config）{//Web API配置和服务//Web API routes config.mapHttpAttribute路由（）；config.routes.MapHttpRoute（名称：“DefaultApi”，routeTemplate:“api/{controller}/{id}”，默认值：new{id=RouteParameter.Optional}；}您需要将此类信息添加到原始帖子中。你可以编辑它。我现在就添加它。

public IHttpActionResult GetArtist(string name) {       
    IEnumerable<Artist> ArtistQuery = from Artist in artists
                                      where Artist.Name.Contains(name)
                                      select Artist;
    if (ArtistQuery.Count() == 0) {
        return NotFound();
    }
    return Ok(ArtistQuery.First());
}

function find() {
    $.getJSON(uri + '/' + name) //This should resolve to you web api endpoint `api/artists/getartist/{name}`
    .done(function (data) {
        if(data) {
            $.each(data, function (key, item)) { 
                // Add a list item for the found artists to artist. 
                $('<li>', { text: formatItem(item) }).appendTo($('#artist'));
            }
        }
    })
    .fail(function (jqXHR,textStatus,err)
    {
        $('#artist').text('Error : ' + err);
    });

}

[RoutePrefix("api/artists")]
public class ArtistsController : ApiController
{
    Artist[] artists = new Artist[]
    {
        new Artist { Name = "Metallica",Id ="65f4f0c5-ef9e-490c-aee3-909e7ae6b2ab",Country ="US",Aliases ="Metalica" },
        new Artist { Name = "Lady Gaga",Id ="650e7db6-b795-4eb5-a702-5ea2fc46c848",Country ="US",Aliases ="Lady Ga Ga,Stefani Joanne Angelina Germanotta" },
        new Artist { Name = "Mumford & Sons",Id ="c44e9c22-ef82-4a77-9bcd-af6c958446d6",Country ="GB",Aliases ="" },
        new Artist { Name = "Mott the Hoople",Id ="435f1441-0f43-479d-92db-a506449a686b",Country ="GB",Aliases ="Mott The Hoppie,Mott The Hopple" },
        new Artist { Name = "Megadeth",Id ="a9044915-8be3-4c7e-b11f-9e2d2ea0a91e",Country ="US",Aliases ="Megadeath" },
        new Artist { Name = "John Coltrane",Id ="b625448e-bf4a-41c3-a421-72ad46cdb831",Country ="US",Aliases ="John Coltraine,John William Coltrane" }
    }
    };
    // GET api/artists
    [HttpGet]
    [Route("")]
    public IEnumerable<Artist> GetAllArtists()
    {
        return artists;
    }

    // GET api/artists/John
    [HttpGet]
    [Route("{name}")]
    public IHttpActionResult GetArtist(string name)
    {        
        IEnumerable<Artist> ArtistQuery = from Artist in artists
                                          where Artist.Name.Contains(name)
                                          select Artist;
        if (ArtistQuery == null)
        {
            return NotFound();
        }
        return Ok(ArtistQuery);
    }
}