生成一個隨機數得到一個隨機列表項

Question

我想從「行情」列表中獲得一個隨機列表項。我目前有一個web部件，它具有用於選擇要顯示的報價類型的自定義屬性。 「行情」列表中引用了以下類別「企業，技術和財務」）。目前，我正在使用一個foreach循環來顯示特定類別的所有引號。我有CAML查詢來過濾要顯示的引號類型。在web部件的自定義屬性中輸入的值用於CAML查詢以顯示引號。

下一步是顯示一個特定類別的隨機引用，但我不太確定如何實現這一點。下面是我的代碼currenlty已經隨機位尚未完成不肯定就如何做到這一點。

protected void Page_Load(object sender, EventArgs e) 
{ 

if (this.WebPart != null && this.WebPart.PracticeArea != null) 
{ 
string PracticeArea = this.WebPart.PracticeArea; //get the value of the property 



//getting a reference to the site location 
string webUrl = SPContext.Current.Site.AllWebs["practices"].Url; 

//Getting the Quotes list 
using (SPSite site = new SPSite(webUrl)) 
{ 
using (SPWeb web = site.OpenWeb()) 
{ 
try 
{ 
//getting the Quotes list 
SPList quotesList = web.Lists["Quotes"]; 

//SPListItemCollection collLisItems = quotesList.Items; not needed 

//CAML query to filter or obtain the correct quote based on Area. Value for Area is 
//passed from the custom property and used in the caml query 
SPQuery quotesbySector = new SPQuery(); 

//creating an object to handle our random list item selection 
//not too sure whether this is correct 
Random rndQuote = new Random(); 

int num = rndQuote.Next(); 



//string camlquery1 = "<Where><Eq>" + "<FieldRef Name='Area'/>" + "</Eq></Where>"; 
string camlquery1 = @" 
<Where> 
<Eq> 
<FieldRef Name='Area'/> 
<Value Type='Text'>" + PracticeArea + @" </Value> 
</Eq> 
</Where>"; 

quotesbySector.Query = camlquery1; 

SPListItemCollection collListItems = quotesList.GetItems(quotesbySector); 

//SPListItem firstQuote = collListItems[0]; 

//for each loop might need to be removed, as we are only interested in getting a 
//random quote and not all quotes 
foreach (SPListItem item in collListItems) 
{ 

string quotes = (string)item["Quote"]; 
string quotesSource = (string)item["Source"]; 
string quotesYear = (string)item["Year"]; 
//string quotesArea = (string)item["Area"]; //not needed used for test purposes 

plhQuotes.Controls.Add(new LiteralControl(quotes + "<br/>" + "<br/>" + quotesSource + 
"<br/>" + "<br/>" + quotesYear + "<br/>" + "<br/>")); 

} 


} 

catch (Exception err) 
{ 
plhErrors.Controls.Add(new LiteralControl(err.ToString())); 
} 
} 
} 






} 

} 

我肯定有一個簡單的方法來實現這一目標。任何的建議是大大的應用調整它。

在此先感謝。

Answer 1

你需要

• 項目的數量，count = collListItems.Count
• 模操作，collListItems[randNumber % count]

Answer 2

我對不起你發佈的代碼似乎有點上的格式，但我周圍的混亂將執行以下操作：

List<String> quoteList = new List<String>(); 
Random rand = new Random(); 
String quote; 

if(quoteList.Count > 0) 
{ 
    int index = rand.Next(quoteList.Count); // Returns 0 through number of items minus 1 
    quote = quoteList[index]; 
} 

Answer 3

只要你將報價劃分到適當的類別列表中，您可以簡單地獲得一個隨機數並從列表中拉出一個項目。

//Assuming individual lists for categories (ex: technologyList) 
//for technology list 
Random random = new Random(seed); //seed is optional 
var itemNumber = random.Next(0, technologyList.Count); 
return technologyList[itemNumber]; 

這是簡單粗暴（和假設你已經封裝在一個方法的功能），但它應該給你一個基本的指路牌。我沒有閱讀完整的代碼示例，因此請根據需要修改此內容以完成工作。

Answer 4

已經設法將其排除。完成如下：

SPListItemCollection collListItems = quotesList.GetItems(quotesbySector); 

//Getting a random list item from based on the PracticeArea value entered in webpart's 
//custom property, which is used in the CAML query above to filter the results returned 
Random randomQuote = new Random(); 
int randItem = randomQuote.Next(0, collListItems.Count); 

collListItems[randItem].ToString(); 

SPListItem ourQuote = collListItems[randItem]; 

string quote = (string)ourQuote["Quote"]; 
string quoteSource = (string)ourQuote["Source"]; 
string quoteYear = (string)ourQuote["Year"]; 

if (quoteYear != null) 
{ 
plhQuotes.Controls.Add(new LiteralControl(quote + "<br/><br/>" + quoteSource + "<br/> 
<br/>" + "Year: " + quoteYear)); 
} 
else 
{ 
plhQuotes.Controls.Add(new LiteralControl(quote + "<br/><br/>" + quoteSource)); 
} 

Sorted !.感謝所有的建議。