我正在尝试创建一个简单的图形项目，用户从下拉列表中选择一个图形，然后加载生成的图形。目前我的图表已加载但会转到交换机的默认部分，正如用户未进行选择所预期的那样。当用户选择＆＃34;图1＆＃34;和点击提交没有真正发生的地址现在显示
http://localhost:51493/GraphDropdownModels?searchGraph=Graph+1
但图表保持不变？
我也尝试在case语句中调用Chart（）：
switch (searchGraph)
{
case "Graph 1":
graphselected = "1";
Chart()
break;
case "Graph 2":
graphselected = "2";
Chart()
break;
case "Graph 3":
graphselected = "3";
Chart()
break;
case "Graph 4":
graphselected = "4";
Chart()
break;
}
然而，这种接缝会循环，但图形图像永远不会被绘制。
有人能指出我的解决方案吗？
Index.cshtml
@model IEnumerable<TestSolution.Models.GraphDropdownModel>
@{
ViewBag.Title = "Index";
}
<h2>Index</h2>
<p>
@Html.ActionLink("Create New", "Create")
@using (Html.BeginForm("Index", "GraphDropdownModels", FormMethod.Get))
{
<p>
Graph: @Html.DropDownList("searchGraph", "Graph 1")
<input type="submit" value="Select" />
</p>
}
@*Render chart here*@
@{ Html.RenderAction("Chart");}
</p>
<table class="table">
<tr>
<th>
@Html.DisplayNameFor(model => model.GraphName)
</th>
<th></th>
</tr>
@foreach (var item in Model)
{
<tr>
<td>
@Html.DisplayFor(modelItem => item.GraphName)
</td>
<td>
@Html.ActionLink("Edit", "Edit", new { id = item.GraphID }) |
@Html.ActionLink("Details", "Details", new { id = item.GraphID }) |
@Html.ActionLink("Delete", "Delete", new { id = item.GraphID })
</td>
</tr>
}
</table>
GraphDropdownModelControler.cs
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Web;
using System.Web.Mvc;
using System.Web.UI.DataVisualization.Charting;
using TestSolution.Models;
namespace TestSolution.Controllers
{
public class GraphDropdownModelsController : Controller
{
private GraphingDBContext db = new GraphingDBContext();
private string graphselected = "Graph 1";
// GET: GraphDropdownModels
public ActionResult Index(string searchGraph)
{
string item1 = "Graph 1";
string item2 = "Graph 2";
string item3 = "Graph 3";
string item4 = "Graph 4";
var GraphLst = new List<string> { item1, item2, item3, item4 };
ViewBag.searchGraph = new SelectList(GraphLst);
switch (searchGraph)
{
case "Graph 1":
graphselected = "1";
break;
case "Graph 2":
graphselected = "2";
break;
case "Graph 3":
graphselected = "3";
break;
case "Graph 4":
graphselected = "4";
break;
}
return View(db.GraphNames.ToList());
}
public ActionResult Chart()
{
var chart = buildChart();
StringBuilder result = new StringBuilder();
result.Append(getChartImage(chart));
result.Append(chart.GetHtmlImageMap("ImageMap"));
return Content(result.ToString());
}
private Chart buildChart()
{
// Build Chart
var chart = new Chart();
chart.Width = 800;
chart.Height = 600;
// Create chart here
chart.Titles.Add(CreateTitle());
chart.Legends.Add(CreateLegend());
chart.ChartAreas.Add(CreateChartArea());
chart.Series.Add(CreateSeries());
return chart;
}
private string getChartImage(Chart chart)
{
using (var stream = new MemoryStream())
{
string img = "<img src='data:image/png;base64,{0}' alt='' usemap='#ImageMap'>";
chart.SaveImage(stream, ChartImageFormat.Png);
string encoded = Convert.ToBase64String(stream.ToArray());
return String.Format(img, encoded);
}
}
private Title CreateTitle()
{
// Create instance of title
Title title = new Title();
// Set title using variable
String chartTitle = "Custom Chart Result";
title.Text = chartTitle;
// Set font style
title.Font = new Font("Trebuchet MS", 14F, FontStyle.Bold);
title.ForeColor = Color.FromArgb(26, 59, 105);
return title;
}
private Legend CreateLegend()
{
//Initializes a new instance of the Legend class.
Legend legend = new Legend();
// show/hide legend
legend.Enabled = true;
//set legend content font style , colour
legend.Font = new Font("Trebuchet MS", 14F, FontStyle.Bold);
legend.ForeColor = Color.FromArgb(26, 59, 105);
// Set legend title
legend.Title = "Legend";
return legend;
}
private ChartArea CreateChartArea()
{
// Initializes a new instance of the ChartArea class called chartArea.
ChartArea chartArea = new ChartArea();
// Sets name of the chart object
chartArea.Name = "Result Chart";
// sets the background color of the ChartArea object.
chartArea.BackColor = Color.LightGray;
// Show Axis labels on/off
chartArea.AxisX.IsLabelAutoFit = true;
chartArea.AxisY.IsLabelAutoFit = true;
// Set axis label font style
chartArea.AxisX.LabelStyle.Font = new Font("Verdana,Arial,Helvetica,sans-serif", 8F, FontStyle.Regular);
chartArea.AxisY.LabelStyle.Font = new Font("Verdana,Arial,Helvetica,sans-serif", 8F, FontStyle.Regular);
// Set colour of x/y edge lines
chartArea.AxisY.LineColor = Color.FromArgb(64, 64, 64, 64);
chartArea.AxisX.LineColor = Color.FromArgb(64, 64, 64, 64);
// Set x/y grid lines colour & set interval between lines
chartArea.AxisY.MajorGrid.LineColor = Color.FromArgb(64, 64, 64, 64);
chartArea.AxisX.MajorGrid.LineColor = Color.FromArgb(64, 64, 64, 64);
chartArea.AxisY.Interval = 1;
chartArea.AxisX.Interval = 1;
return chartArea;
}
public Series CreateSeries()
{
Series seriesDetail = new Series();
// adjust legend data name
seriesDetail.Name = "Result!";
seriesDetail.IsValueShownAsLabel = false;
// Sets Colour of Bar/Segments/Data ect
seriesDetail.Color = Color.FromArgb(198, 99, 99);
// Set the Chart Type
seriesDetail.ChartType = SeriesChartType.Column;
// NO IDEA ATM
seriesDetail.BorderWidth = 1;
// Adjust the Chart Series values used for X + Y
if (!String.IsNullOrEmpty(graphselected))
{
switch(graphselected)
{
case "1":
seriesDetail.Points.AddXY("Cats", 1);
seriesDetail.Points.AddXY("Dogs", 3);
seriesDetail.Points.AddXY("Bats", 5);
seriesDetail.Points.AddXY("Mouse", 2);
break;
case "2":
seriesDetail.Points.AddXY("Cats", 10);
seriesDetail.Points.AddXY("Dogs", 30);
seriesDetail.Points.AddXY("Bats", 50);
seriesDetail.Points.AddXY("Mouse", 20);
break;
case "3":
seriesDetail.Points.AddXY("Cats", 100);
seriesDetail.Points.AddXY("Dogs", 300);
seriesDetail.Points.AddXY("Bats", 500);
seriesDetail.Points.AddXY("Mouse", 200);
break;
case "4":
seriesDetail.Points.AddXY("Cats", 1000);
seriesDetail.Points.AddXY("Dogs", 3000);
seriesDetail.Points.AddXY("Bats", 5000);
seriesDetail.Points.AddXY("Mouse", 2000);
break;
default:
seriesDetail.Points.AddXY("H", 1);
seriesDetail.Points.AddXY("E", 5);
seriesDetail.Points.AddXY("L", 5);
seriesDetail.Points.AddXY("P", 1);
break;
}
}
//sets the name of the ChartArea object used to plot the data series
seriesDetail.ChartArea = "Result Chart";
return seriesDetail;
}
// GET: GraphDropdownModels/Details/5
public ActionResult Details(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
GraphDropdownModel graphDropdownModel = db.GraphNames.Find(id);
if (graphDropdownModel == null)
{
return HttpNotFound();
}
return View(graphDropdownModel);
}
// GET: GraphDropdownModels/Create
public ActionResult Create()
{
return View();
}
// POST: GraphDropdownModels/Create
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create([Bind(Include = "GraphID,GraphName")] GraphDropdownModel graphDropdownModel)
{
if (ModelState.IsValid)
{
db.GraphNames.Add(graphDropdownModel);
db.SaveChanges();
return RedirectToAction("Index");
}
return View(graphDropdownModel);
}
// GET: GraphDropdownModels/Edit/5
public ActionResult Edit(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
GraphDropdownModel graphDropdownModel = db.GraphNames.Find(id);
if (graphDropdownModel == null)
{
return HttpNotFound();
}
return View(graphDropdownModel);
}
// POST: GraphDropdownModels/Edit/5
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit([Bind(Include = "GraphID,GraphName")] GraphDropdownModel graphDropdownModel)
{
if (ModelState.IsValid)
{
db.Entry(graphDropdownModel).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
return View(graphDropdownModel);
}
// GET: GraphDropdownModels/Delete/5
public ActionResult Delete(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
GraphDropdownModel graphDropdownModel = db.GraphNames.Find(id);
if (graphDropdownModel == null)
{
return HttpNotFound();
}
return View(graphDropdownModel);
}
// POST: GraphDropdownModels/Delete/5
[HttpPost, ActionName("Delete")]
[ValidateAntiForgeryToken]
public ActionResult DeleteConfirmed(int id)
{
GraphDropdownModel graphDropdownModel = db.GraphNames.Find(id);
db.GraphNames.Remove(graphDropdownModel);
db.SaveChanges();
return RedirectToAction("Index");
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
db.Dispose();
}
base.Dispose(disposing);
}
}
}
答案 0 :(得分：0)
好的找到了我的问题的解决方案。
问题是变量，公共字符串graphselected;在变量上添加监视后，我可以看到在代码运行时值被删除，因此值始终为null。所需要的只是添加“＃34; static＆＃34;确保变量不会被丢弃。
修复：公共静态字符串graphselected;