在asp.net c＃中限制datagrid项目

Limit datagrid items in asp.net c#

我在ASP.NET C中使用DataGrid。我想限制和控制DataGrid中显示的项目数(我被迫使用此控制器)。

我知道我们可以控制使用

每页按AllowPaging ="TRUE"计算

使用sql查询限制DataSource，然后绑定(DataBind()它。

但我也不想要。我想运行一次sql查询并获取所有数据，然后我必须能够根据需要显示前10或20个项目。

如果我能做到最好

在代码隐藏中。

不重新加载页面，如果我将项目大小从10增加到30

在正确的道路上昂首挺胸的任何一种人都会受到赞赏

相关讨论

然而，当我们使用DataGrid控制时，我们必须在datasource中添加一个list(可以是任何类型的列表)。

我们要做的就是限制这个list中的项目数量，然后使用DataBind()绑定数据。

限制数据数量

1	var firstFiveItems = myList.Take(5);

或

1	var secondFiveItems = myList.Skip(5).Take(5);

。

这里有两个选项可以考虑。第一种方法是使用DataTable和Linq来获取顶部的x行。

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DataTable dt = yourDataTableSource;
GridView1.DataSource = dt.AsEnumerable().Take(5).CopyToDataTable();
//Linq example with sorting added
//GridView1.DataSource = dt.AsEnumerable().OrderBy(x => x["columnName"]).Take(5).CopyToDataTable();
GridView1.DataBind();

或者可以使用通常在.aspx页上找到的相同属性。现在只有在代码隐藏中设置了这些，您仍然可以为此使用当前的数据源。

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GridView1.PageSize = 5;
GridView1.AllowPaging = true;
GridView1.PagerSettings.Visible = false;
GridView1.DataBind();

。

或者对于数据报

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DataGrid1.PageSize = 10;
DataGrid1.AllowPaging = true;
DataGrid1.PagerStyle.Visible = false;
DataGrid1.DataBind();

为了完成你的问题，这里有一个小例子，让你开始如何在不刷新页面的情况下获取显示项目中的更改。

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</asp:ScriptManager>


<ContentTemplate>

</asp:GridView>
<br />

</asp:ListItem>
</asp:ListItem>
</asp:ListItem>
</asp:DropDownList>

</ContentTemplate>
</asp:UpdatePanel>

。

代码隐藏：

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protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
DataTable dt = yourDataTableSource;
GridView1.DataSource = dt;
GridView1.PageSize = 10;
GridView1.AllowPaging = true;
GridView1.PagerSettings.Visible = false;
GridView1.DataBind();

ViewState["GridView1Content"] = dt;
}
}

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
int pageSize = 10;

//always do validation with user input...
try
{
pageSize = Convert.ToInt32(DropDownList1.SelectedValue);
}
catch
{
}

GridView1.PageSize = pageSize;
GridView1.DataSource = ViewState["GridView1Content"] as DataTable;
GridView1.DataBind();
}

。

相关讨论

我是这样来的，但我使用的是GridView，当页面太过加载时，我就迁移到具有服务器端页面处理的数据表中。

它是一个通用层。根据你的需要修改它！

下面是我得到的解析器：

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Web;

namespace iMax_WeSite.app.Objects.DataTables
{
public class DataTable
{
public DataTable()
{
}
public int sEcho { get; set; }
public int iTotalRecords { get; set; }
public int iTotalDisplayRecords { get; set; }
public string iTotalValue { get; set; } //Somatoria total do valor
public string iTotalFilteredValue { get; set; } //Somatoria parcial do valor
public List<List<string>> aaData { get; set; }
public string sColumns { get; set; }

public void Import(string[] properties)
{
sColumns = string.Empty;
for (int i = 0; i < properties.Length; i++)
{
sColumns += properties[i];
if (i < properties.Length - 1)
sColumns +=",";
}
}
}
public class DataTableParser<T>
{
private const string INDIVIDUAL_SEARCH_KEY_PREFIX ="sSearch_";
private const string INDIVIDUAL_SORT_KEY_PREFIX ="iSortCol_";
private const string INDIVIDUAL_SORT_DIRECTION_KEY_PREFIX ="sSortDir_";
private const string DISPLAY_START ="iDisplayStart";
private const string DISPLAY_LENGTH ="iDisplayLength";
private const string ECHO ="sEcho";
private const string SEARCH ="sSearch";
private const string ASCENDING_SORT ="asc";
private IQueryable<T> _queriable;
private readonly Dictionary<string, object> _tableParams;
private readonly Type _type;
private readonly System.Reflection.PropertyInfo[] _properties;
public DataTableParser(Dictionary<string, object> tableParams, IQueryable<T> queriable)
{
_queriable = queriable;
_tableParams = tableParams;
_type = typeof(T);
_properties = _type.GetProperties();
}

public DataTable Parse()
{
var list = new DataTable();
list.Import(_properties.Select(x => x.Name).ToArray());

list.sEcho = (int)_tableParams[ECHO];

list.iTotalRecords = _queriable.Count();

ApplySort();

int skip = 0, take = list.iTotalRecords;
if (_tableParams.ContainsKey(DISPLAY_START))
skip = (int)_tableParams[DISPLAY_START];
if (_tableParams.ContainsKey(DISPLAY_LENGTH))
take = (int)_tableParams[DISPLAY_LENGTH];

//tenho de segregar para mostrar o filtrado
list.aaData = _queriable.Where(ApplyGenericSearch)
.Where(IndividualPropertySearch)
.Skip(skip)
.Take(take)
.Select(SelectProperties)
.ToList();

//tenho de segregar para mostrar o filtrado geral
list.iTotalDisplayRecords = _queriable.Where(ApplyGenericSearch)
.Where(IndividualPropertySearch)
.Select(SelectProperties)
.Count();
return list;
}
private void ApplySort()
{
foreach (string key in _tableParams.Keys.Where(x => x.StartsWith(INDIVIDUAL_SORT_KEY_PREFIX)))
{
int sortcolumn = (int)_tableParams[key];
if (sortcolumn < 0 || sortcolumn >= _properties.Length)
break;

string sortdir = _tableParams[INDIVIDUAL_SORT_DIRECTION_KEY_PREFIX + key.Replace(INDIVIDUAL_SORT_KEY_PREFIX, string.Empty)].ToString();

var paramExpr = Expression.Parameter(typeof(T),"val");
var propertyExpr = Expression.Lambda<Func<T, object>>(Expression.Convert(Expression.Property(paramExpr, _properties[sortcolumn]), typeof(object)), paramExpr);

if (string.IsNullOrEmpty(sortdir) || sortdir.Equals(ASCENDING_SORT, StringComparison.OrdinalIgnoreCase))
_queriable = _queriable.OrderBy(propertyExpr);
else
_queriable = _queriable.OrderByDescending(propertyExpr);
}
}

private Expression<Func<T, List<string>>> SelectProperties
{
get
{
return value => _properties.Select
(
prop => (prop.GetValue(value, new object[0]) ?? string.Empty).ToString()
)
.ToList();
}
}

private Expression<Func<T, bool>> IndividualPropertySearch
{
get
{
var paramExpr = Expression.Parameter(typeof(T),"val");
Expression whereExpr = Expression.Constant(true); // default is val => True
foreach (string key in _tableParams.Keys.Where(x => x.StartsWith(INDIVIDUAL_SEARCH_KEY_PREFIX)))
{
int property = -1;

if (!int.TryParse(key.Replace(INDIVIDUAL_SEARCH_KEY_PREFIX, string.Empty), out property) || property >= _properties.Length || string.IsNullOrEmpty(_tableParams[key].ToString()))
continue; // ignore if the option is invalid

string query = _tableParams[key].ToString().ToLower();

var toStringCall = Expression.Call(
Expression.Call(
Expression.Property(paramExpr, _properties[property]),"ToString", new Type[0]),
typeof(string).GetMethod("ToLower", new Type[0]));

whereExpr = Expression.And(whereExpr,
Expression.Call(toStringCall,
typeof(string).GetMethod("Contains", BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance | BindingFlags.IgnoreCase),
Expression.Constant(query)));

}
return Expression.Lambda<Func<T, bool>>(whereExpr, paramExpr);
}
}

private Expression<Func<T, bool>> ApplyGenericSearch
{
get
{
if (!_tableParams.ContainsKey(SEARCH) || _properties.Length == 0)
return x => true;

string search = _tableParams[SEARCH].ToString();

if (String.IsNullOrEmpty(search))
return x => true;

var searchExpression = Expression.Constant(search.ToLower());
var paramExpression = Expression.Parameter(typeof(T),"val");

var propertyQuery = (from property in _properties
let tostringcall = Expression.Call(
Expression.Call(
Expression.Property(paramExpression, property),"ToString", new Type[0]),
typeof(string).GetMethod("ToLower", new Type[0]))
select Expression.Call(tostringcall, typeof(string).GetMethod("Contains"), searchExpression)).ToArray();

Expression compoundExpression = propertyQuery[0];

for (int i = 1; i < propertyQuery.Length; i++)
compoundExpression = Expression.Or(compoundExpression, propertyQuery[i]);

return Expression.Lambda<Func<T, bool>>(compoundExpression, paramExpression);
}
}

}

}

希望我帮了你的忙！

您是否尝试过DataTable插件？它具有根据我们的要求显示记录的功能。查看此链接

为网格应用DataTable插件以显示数据，您可以根据需要更改aLengthMenu和iDisplayLength属性来更改此选项。这是内置功能

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$(document).ready(function() {
$('#example').dataTable({
"aLengthMenu": [[10, 20, 30, -1], [10, 20, 30,"All"]],// set as per your requirement
"iDisplayLength": 10 // dont forget to change as per alengthmenu

});
} );

号