ASP.NET Core 3.1 中的数据表服务器端处理

Question

我是使用 AJAX 调用的数据表的新手。我需要对数千条记录实施服务器端处理。我正在学习教程，但我对服务器端处理感到困惑。

我在尝试从数据源呈现数据时收到错误。让我发布所有相关代码，希望您能帮助我找出哪里出错了。由于我是Datatables和 Ajax 的新手，因此我将欣赏更多带有示例的答案、文本答案以及演示ASP.NET CORE 3.1中服务器端处理的教程的代码或链接。

感谢您的时间和帮助。

注意。我从教程中获取了实现和配置，并尝试对其进行自定义。

下面是 HTML 表格及其模型：

@model IEnumerable<StudentApplications>
<table id="custom-datatable" class="mb-5 display table table-bordered" style="width:100%">
                <thead>
                    <tr>
                        <th>
                            @Html.DisplayNameFor(model => model.ApplicationId)
                        </th>
                        <th>
                            @Html.DisplayNameFor(model => model.Firstname)
                        </th>
                        <th>
                            @Html.DisplayNameFor(model => model.Surname)
                        </th>
                        <th>
                            @Html.DisplayNameFor(model => model.ApplicationFor)
                        </th>
                        <th>
                            @Html.DisplayNameFor(model => model.SubmissionDate)
                        </th>
                        <th></th>
                    </tr>
                </thead>
                <tfoot>
                    <tr>
                        <th>
                            @Html.DisplayNameFor(model => model.ApplicationId)
                        </th>
                        <th>
                            @Html.DisplayNameFor(model => model.Firstname)
                        </th>
                        <th>
                            @Html.DisplayNameFor(model => model.Surname)
                        </th>
                        <th>
                            @Html.DisplayNameFor(model => model.ApplicationFor)
                        </th>
                        <th>
                            @Html.DisplayNameFor(model => model.SubmissionDate)
                        </th>
                        <th></th>
                    </tr>
                </tfoot>
            </table>

下面是将 HTML 表初始化为数据表的 javascript 文件和一些配置：

$(document).ready(function () {
    $('#custom-datatable').DataTable({

        // Design Assets
        stateSave: true,
        autoWidth: true,
        // ServerSide Setups
        processing: true,
        serverSide: true,
        // Paging Setups
        paging: true,
        // Searching Setups
        searching: { regex: true },
        // Ajax Filter
        ajax: {
            url: "/myapplications/data",
            type: "POST",
            contentType: "application/json",
            dataType: "json",
            data: function (d) {
                return JSON.stringify(d);
            }
        },
        // Columns Setups
        columns: [
            { data: "ApplicationId" },
            { data: "Firstname" },
            { data: "Surname" },
            { data: "ApplicationFor" },
            { data: "SubmissionDate" }

            //// For Student.Id
            //{ "data": "applicationId", "name": "ApplicationId" },
            //// For Student.Firstname
            //{ "data": "firstname", "name": "Firstname" },
            //// For Student.Surname
            //{ "data": "surname", "name": "Surname" },
            //// For Student.ApplicationFor
            //{ "data": "applicationFor", "name": "ApplicationFor" },
            //// For Student.SubmissionDate
            //{ "data": "submissionDate", "name": "SubmissionDate" }
        ],
        // Column Definitions
        columnDefs: [
            { targets: "no-sort", orderable: false },
            { targets: "no-search", searchable: false },
            {
                targets: "trim",
                render: function (data, type, full, meta) {
                    if (type === "display") {
                        data = strtrunc(data, 10);
                    }

                    return data;
                }
            },
            { targets: "date-type", type: "date-eu" },
            {
                targets: 10,
                data: null,
                orderable: false
            },
        ]
    });

});

下面是获取数据的方法：

// loading datatable
        [HttpPost]
        [Route("myapplications/data")]
        public async Task<IActionResult> Data([FromBody] DtParameters dtParameters)
        { 
            searchBy = dtParameters.Search?.Value;

            // if we have an empty search then just order the results by Id ascending
            var orderCriteria = "ApplicationId";
            var orderAscendingDirection = true;

            if (dtParameters.Order != null)
            {
                // in this example we just default sort on the 1st column
                orderCriteria = dtParameters.Columns[dtParameters.Order[0].Column].Data;
                orderAscendingDirection = dtParameters.Order[0].Dir.ToString().ToLower() == "asc";
            }

            var result = context.AspNetStudentApplications.AsQueryable();

            if (!string.IsNullOrEmpty(searchBy))
            {
                result = result.Where(r => r.ApplicationId != null && r.ApplicationId.ToUpper().Contains(searchBy.ToUpper()) ||
                                           r.Firstname != null && r.Firstname.ToUpper().Contains(searchBy.ToUpper()) ||
                                           r.Surname != null && r.Surname.ToUpper().Contains(searchBy.ToUpper()) ||
                                           r.ApplicationFor != null && r.ApplicationFor.ToUpper().Contains(searchBy.ToUpper()) ||
                                           r.SubmissionDate != null && r.SubmissionDate.ToUpper().Contains(searchBy.ToUpper()));
            }

            result = orderAscendingDirection ? result.OrderByDynamic(orderCriteria, DtOrderDir.Asc) : result.OrderByDynamic(orderCriteria, DtOrderDir.Desc);

            // now just get the count of items (without the skip and take) - eg how many could be returned with filtering
            var filteredResultsCount = await result.CountAsync();
            var totalResultsCount = await context.AspNetStudentApplications.CountAsync();

            return Json(new DtResult<StudentApplications>
            {
                Draw = dtParameters.Draw,
                RecordsTotal = totalResultsCount,
                RecordsFiltered = filteredResultsCount,
                Data = await result
                    .Skip(dtParameters.Start)
                    .Take(dtParameters.Length)
                    .ToListAsync()
            });
        }

下面是DtParameters类以及与Datatables相关的其他类：

/// <summary>
/// A full result, as understood by jQuery DataTables.
/// </summary>
/// <typeparam name="T">The data type of each row.</typeparam>
public class DtResult<T>
{
    /// <summary>
    /// The draw counter that this object is a response to - from the draw parameter sent as part of the data request.
    /// Note that it is strongly recommended for security reasons that you cast this parameter to an integer, rather than simply echoing back to the client what it sent in the draw parameter, in order to prevent Cross Site Scripting (XSS) attacks.
    /// </summary>
    [JsonProperty("draw")]
    public int Draw { get; set; }

    /// <summary>
    /// Total records, before filtering (i.e. the total number of records in the database)
    /// </summary>
    [JsonProperty("recordsTotal")]
    public int RecordsTotal { get; set; }

    /// <summary>
    /// Total records, after filtering (i.e. the total number of records after filtering has been applied - not just the number of records being returned for this page of data).
    /// </summary>
    [JsonProperty("recordsFiltered")]
    public int RecordsFiltered { get; set; }

    /// <summary>
    /// The data to be displayed in the table.
    /// This is an array of data source objects, one for each row, which will be used by DataTables.
    /// Note that this parameter's name can be changed using the ajax option's dataSrc property.
    /// </summary>
    [JsonProperty("data")]
    public IEnumerable<T> Data { get; set; }

    /// <summary>
    /// Optional: If an error occurs during the running of the server-side processing script, you can inform the user of this error by passing back the error message to be displayed using this parameter.
    /// Do not include if there is no error.
    /// </summary>
    [JsonProperty("error", NullValueHandling = NullValueHandling.Ignore)]
    public string Error { get; set; }

    public string PartialView { get; set; }
}

/// <summary>
/// The additional columns that you can send to jQuery DataTables for automatic processing.
/// </summary>
public abstract class DtRow
{
    /// <summary>
    /// Set the ID property of the dt-tag tr node to this value
    /// </summary>
    [JsonProperty("DT_RowId")]
    public virtual string DtRowId => null;

    /// <summary>
    /// Add this class to the dt-tag tr node
    /// </summary>
    [JsonProperty("DT_RowClass")]
    public virtual string DtRowClass => null;

    /// <summary>
    /// Add the data contained in the object to the row using the jQuery data() method to set the data, which can also then be used for later retrieval (for example on a click event).
    /// </summary>
    [JsonProperty("DT_RowData")]
    public virtual object DtRowData => null;

    /// <summary>
    /// Add the data contained in the object to the row dt-tag tr node as attributes.
    /// The object keys are used as the attribute keys and the values as the corresponding attribute values.
    /// This is performed using using the jQuery param() method.
    /// Please note that this option requires DataTables 1.10.5 or newer.
    /// </summary>
    [JsonProperty("DT_RowAttr")]
    public virtual object DtRowAttr => null;
}

/// <summary>
/// The parameters sent by jQuery DataTables in AJAX queries.
/// </summary>
public class DtParameters
{
    /// <summary>
    /// Draw counter.
    /// This is used by DataTables to ensure that the Ajax returns from server-side processing requests are drawn in sequence by DataTables (Ajax requests are asynchronous and thus can return out of sequence).
    /// This is used as part of the draw return parameter (see below).
    /// </summary>
    public int Draw { get; set; }

    /// <summary>
    /// An array defining all columns in the table.
    /// </summary>
    public DtColumn[] Columns { get; set; }

    /// <summary>
    /// An array defining how many columns are being ordering upon - i.e. if the array length is 1, then a single column sort is being performed, otherwise a multi-column sort is being performed.
    /// </summary>
    public DtOrder[] Order { get; set; }

    /// <summary>
    /// Paging first record indicator.
    /// This is the start point in the current data set (0 index based - i.e. 0 is the first record).
    /// </summary>
    public int Start { get; set; }

    /// <summary>
    /// Number of records that the table can display in the current draw.
    /// It is expected that the number of records returned will be equal to this number, unless the server has fewer records to return.
    /// Note that this can be -1 to indicate that all records should be returned (although that negates any benefits of server-side processing!)
    /// </summary>
    public int Length { get; set; }

    /// <summary>
    /// Global search value. To be applied to all columns which have searchable as true.
    /// </summary>
    public DtSearch Search { get; set; }

    /// <summary>
    /// Custom column that is used to further sort on the first Order column.
    /// </summary>
    public string SortOrder => Columns != null && Order != null && Order.Length > 0
        ? (Columns[Order[0].Column].Data +
           (Order[0].Dir == DtOrderDir.Desc ? " " + Order[0].Dir : string.Empty))
        : null;

    /// <summary>
    /// For Posting Additional Parameters to Server
    /// </summary>
    public IEnumerable<string> AdditionalValues { get; set; }

}

/// <summary>
/// A jQuery DataTables column.
/// </summary>
public class DtColumn
{
    /// <summary>
    /// Column's data source, as defined by columns.data.
    /// </summary>
    public string Data { get; set; }

    /// <summary>
    /// Column's name, as defined by columns.name.
    /// </summary>
    public string Name { get; set; }

    /// <summary>
    /// Flag to indicate if this column is searchable (true) or not (false). This is controlled by columns.searchable.
    /// </summary>
    public bool Searchable { get; set; }

    /// <summary>
    /// Flag to indicate if this column is orderable (true) or not (false). This is controlled by columns.orderable.
    /// </summary>
    public bool Orderable { get; set; }

    /// <summary>
    /// Search value to apply to this specific column.
    /// </summary>
    public DtSearch Search { get; set; }
}

/// <summary>
/// An order, as sent by jQuery DataTables when doing AJAX queries.
/// </summary>
public class DtOrder
{
    /// <summary>
    /// Column to which ordering should be applied.
    /// This is an index reference to the columns array of information that is also submitted to the server.
    /// </summary>
    public int Column { get; set; }

    /// <summary>
    /// Ordering direction for this column.
    /// It will be dt-string asc or dt-string desc to indicate ascending ordering or descending ordering, respectively.
    /// </summary>
    public DtOrderDir Dir { get; set; }
}

/// <summary>
/// Sort orders of jQuery DataTables.
/// </summary>
public enum DtOrderDir
{
    Asc,
    Desc
}

/// <summary>
/// A search, as sent by jQuery DataTables when doing AJAX queries.
/// </summary>
public class DtSearch
{
    /// <summary>
    /// Global search value. To be applied to all columns which have searchable as true.
    /// </summary>
    public string Value { get; set; }

    /// <summary>
    /// true if the global filter should be treated as a regular expression for advanced searching, false otherwise.
    /// Note that normally server-side processing scripts will not perform regular expression searching for performance reasons on large data sets, but it is technically possible and at the discretion of your script.
    /// </summary>
    public bool Regex { get; set; }
}

这是我的空表：

以下是我在尝试加载数据时遇到的错误：

我哪里理解错了？

这是发生异常的地方：

@HMZ 实现，我看到空记录（下图）：

我看到这个警报

卡在处理中

当行数更改时，我看到这个空表：

Answer 1

这是数据表服务器端处理的工作示例。这是一个示例，可能需要修改才能在您的应用程序中工作。

代码

Datatables表参数：

[ModelBinder(BinderType = typeof(DataTableModelBinder))]
public class DataTablesResult
{
    public int Draw { get; set; }
    public int Start { get; set; }
    public int Length { get; set; }
    public Search Search { get; set; }
    public List<ColumnOrder> Order { get; set; }
    public List<Column> Columns { get; set; }
}

public class Search
{
    public string Value { get; set; }
    public bool Regex { get; set; }
}

public class Column
{
    public string Data { get; set; }
    public string Name { get; set; }
    public bool Searchable { get; set; }
    public bool Orderable { get; set; }
    public Search Search { get; set; }
}

public class ColumnOrder
{
    public int Column { get; set; }
    public string Dir { get; set; }
}

自定义模型绑定器，以便DataTablesResult在服务器端正确绑定表参数：

public class DataTableModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        var request = bindingContext.HttpContext.Request;

        // Retrieve request data
        var draw = Convert.ToInt32(request.Query["draw"]);
        var start = Convert.ToInt32(request.Query["start"]);
        var length = Convert.ToInt32(request.Query["length"]);

        // Search
        var search = new Search
        {
            Value = request.Query["search[value]"],
            Regex = Convert.ToBoolean(request.Query["search[regex]"])
        };

        // Order
        var o = 0;
        var order = new List<ColumnOrder>();
        while (!StringValues.IsNullOrEmpty(request.Query["order[" + o + "][column]"]))
        {
            order.Add(new ColumnOrder
            {
                Column = Convert.ToInt32(request.Query["order[" + o + "][column]"]),
                Dir = request.Query["order[" + o + "][dir]"]
            });
            o++;
        }

        // Columns
        var c = 0;
        var columns = new List<Column>();
        while (!StringValues.IsNullOrEmpty(request.Query["columns[" + c + "][name]"]))
        {
            columns.Add(new Column
            {
                Data = request.Query["columns[" + c + "][data]"],
                Name = request.Query["columns[" + c + "][name]"],
                Orderable = Convert.ToBoolean(request.Query["columns[" + c + "][orderable]"]),
                Searchable = Convert.ToBoolean(request.Query["columns[" + c + "][searchable]"]),
                Search = new Search
                {
                    Value = request.Query["columns[" + c + "][search][value]"],
                    Regex = Convert.ToBoolean(request.Query["columns[" + c + "][search][regex]"])
                }
            });
            c++;
        }

        var result = new DataTablesResult
        {
            Draw = draw,
            Start = start,
            Length = length,
            Search = search,
            Order = order,
            Columns = columns
        };

        bindingContext.Result = ModelBindingResult.Success(result);
        return Task.CompletedTask;
    }
}

服务器端动作：

[HttpGet]
public async Task<IActionResult> DataAjax(DataTablesResult tableParams)
{
    var query = dataWrapper.YourDataSet.GetAll();

    var totalCount = await query.CountAsync();

    if (tableParams.Search != null)
        query = query.Where(c => c.Firstname.Contains(tableParams.Search.Value)
        || c.Surname.Contains(tableParams.Search.Value));
       //Other search queries goes here

    if (tableParams.Order.Count > 0)
    {
        if (tableParams.Order[0].Dir == "asc")
            query = query.OrderBy(c => EF.Property<string>(c, tableParams.Columns[tableParams.Order[0].Column].Name));
        else
            query = query.OrderByDescending(c => EF.Property<string>(c, tableParams.Columns[tableParams.Order[0].Column].Name));
    }
    //In this example multi order is disabled so we can order by any column dynamically

    var result = await query.AsNoTracking().Select(E => new { Count = query.Count(), E = E }).Skip(tableParams.Start).Take(tableParams.Length).ToListAsync();
    var pureData = result.Select(E => E.E);

    if (result.Count == 0)
        return Ok(new { tableParams.Draw, recordsTotal = 0, recordsFiltered = 0, data = Enumerable.Empty<string>() });

    return Ok(new { tableParams.Draw, recordsTotal = totalCount, recordsFiltered = result.Select(c => c.Count).FirstOrDefault(), data = pureData });
}

数据表配置：

var table = $("#dataTable").DataTable({
    serverSide: true,
    processing: true,
    ajax: {
        url: "/Controller/DataAjax",
        method: "GET",
        dataType: "json"
    },
    select: true,
    orderMulti: false, //Multi column order is disabled
    columnDefs: [{
        targets: [], //Here you can specify targets for cell ellipsis
        render: $.fn.dataTable.render.ellipsis(10, true)
    },
    {
        targets: [], //Disable search on targeted columns
        searchable: false
    },
    {
        targets: [], //Disable order on targeted columns
        orderable: false
    }],
    columns: [
        { "name": "ApplicationId" } //Here your column names should match your db columns in order to have dynamic order.
    ]
});