C# 使用 LINQ to SQL 对搜索结果进行分页
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Paginated search results with LINQ to SQL
提问by Pablo Santa Cruz
What's the best pattern to get paginated results with LINQ to SQL?
使用LINQ to SQL获得分页结果的最佳模式是什么？
I have the following scenario:
我有以下场景：
Suppose I want to search itemstable by description. I can easily do:
假设我想通过description搜索items表。我可以轻松做到：
public IQueryable<Item> FindItemsByDescription(string description)
{
return from item in _dc.Items
where item.Description.Contains(description);
}
Now, what would be the best way to paginate this result set?
现在，对这个结果集进行分页的最佳方是什么？
- Should I perform a countquery before doing this to find out the result set size and then limit this query according to what I want? I feel like this is the way to go.
- Should I perform the full query, take the count from the array size and return only a paginated subset from this array? I feel like this will be a huge waste of time if the resultset is big enough... Or is LINQ to SQLdoing some magic here?
- 我是否应该在执行此操作之前执行计数查询以找出结果集大小，然后根据我的需要限制此查询？我觉得这是要走的路。
- 我是否应该执行完整查询，从数组大小中获取计数并仅从该数组中返回一个分页子集？如果结果集足够大，我觉得这将是一个巨大的浪费......或者LINQ to SQL在这里做了一些魔术？
Is there a LINQ to SQLcommon pattern for performing this operation?
是否有用于执行此操作的LINQ to SQL通用模式？
EDIT: I mustclarify a one little thing. I am aware of Take and Skip methods. But, before using Takeand Skip, how should I get the total countof results that query would retrieve?
编辑：我必须澄清一件小事。我知道 Take 和 Skip 方。但是，在使用Take和Skip之前，我应该如何获得查询将检索到的结果总数？
采纳答案by Jose Basilio
The pattern for paging is very simple. It involves the use of the Skip() and Take() extension methods as follows:
分页模式非常简单。它涉及到 Skip() 和 Take() 扩展方的使用，如下所示：
public IQueryable<Item> FindItemsByDescription(string description, int pageIndex, int pageSize)
{
return from item in _dc.Items
where item.Description.
Contains(description).
Skip((pageIndex - 1) * pageSize).
Take(pageSize);
}
UPDATE:To get the total count simply use the Count() method:
更新：要获得总计数，只需使用 Count() 方：
int totalCount = from item in _dc.Items
where item.Description.
Contains(description).Count();
int numberOfPages = (int)(totalCount/pageSize);
Depending on how you are going to the display the records, you can use the numberOfPages to display a navigation bar with "Page X of Y" ... Page 1 of 10, etc..
根据您要显示记录的方式，您可以使用 numberOfPages 来显示带有“第 X 页，共 Y 页”的导航栏......第 1 页，共 10 页，等等。
回答by BFree
You can use the Take extension method:
您可以使用 Take 扩展方：
public IQueryable<Item> FindItemsByDescription(string description, int resultAmount)
{
return from item in _dc.Items
where item.Description.Contains(description).Take(resultAmount);
}
You can take this one step further and use Skip for subsequent "pages":
您可以更进一步，对后续的“页面”使用跳过：
public IQueryable<Item> FindItemsByDescription(string description, int resultAmount, int page)
{
return from item in _dc.Items
where item.Description.Contains(description).Skip(resultAmount * page).Take(resultAmount);
}
