如何使用MySQL和ColdFusion创建分页函数

Question

我正在尝试使用MySQL和ColdFusion为搜索结果创建分页.我的目的是只检索可以在单个页面上显示的查询,从而使该过程高效.我尝试在我的函数中使用两个查询,但我无法返回两个变量cfinvoke.

以下代码不分页,但它使用CFC显示结果搜索结果:

<!---DEFINE DEFAULT STATE--->
<cfparam name="variables.searchResponse" default="">
<cfparam name="URL.titleName" default="">
<cfparam name="URL.genreID" default="">
<cfparam name="URL.platformID" default="">

<!---TitleName can only be blank if one or both genre and platform are selected--->
<cfif StructKeyExists(URL, "searchQuery") AND (Len(Trim(URL.titleName)) LTE 2 AND Len(URL.genreID) IS 0 AND Len(URL.platformID) IS 0)>
    <cfset variables.searchResponse = "invalidString">
<cfelseif StructKeyExists(URL, "searchQuery")>
    <cfinvoke component="gz.cfcomp.test" method="searchGames" returnvariable="resultData" argumentcollection="#URL#">
    <cfset variables.searchResponse = "hasResult">
</cfif>

<cfif searchResponse EQ "hasResult" AND resultData.RecordCount EQ 0>
    <cfset variables.searchResponse = "noResult">
</cfif>

使用这个逻辑,我可以显示我需要在页面上显示的内容:

<cfif searchResponse EQ "invalidString">
     <cfoutput>Invalid search</cfoutput>
</cfif>
<cfif searchResponse EQ "noResult">
     <cfoutput>No results found</cfoutput>
</cfif>
<cfif searchResponse EQ "hasResult">
     <cfoutput>Display Results</cfoutput>
</cfif>

如果我在同一页面上执行查询,那么很容易就可以按照那里的许多教程进行操作.但查询正在函数中执行.显示数据很简单,但对它进行分页已成为我的噩梦.这是我的功能:

<cffunction name="searchGames" access="public" output="false">
    <cfargument name="titleName" required="no" type="string">
    <cfargument name="genreID" required="no" type="string">
    <cfargument name="platformID" required="no" type="string">    

    <!--- DEFINE LOCAL VARIABLES--->
    <cfset var resultData = "">        
    <!---GET DATA--->
    <cfquery name="resultData" datasource="myDSN">
        SELECT *
            <!---JOINS FOR GENRE/PLATFORM GO HERE--->
        WHERE
            <!---CONDITIONS GO HERE--->
    </cfquery>
    <!---RETURN VARIABLE--->
    <cfreturn resultData>
</cffunction>   

为了分页,我考虑将我的函数修改为以下(使用count语句的新查询):

<!--- DEFINE LOCAL VARIABLES--->
<cfset var resultCount = "">        
<!---GET DATA--->
<cfquery name="resultCount" datasource="myDSN">
    SELECT COUNT(gameID) AS rowsFound FROM GAMES
        <!---JOINS FOR GENRE/PLATFORM GO HERE--->
    WHERE
        <!---CONDITIONS GO HERE--->
</cfquery>
<!---RETURN VARIABLE--->
<cfreturn resultCount>

然后我想如果有返回的结果,我会执行嵌套查询并创建分页变量:

<cfif resultCount.rowsFound GTE 0>
<cfparam name="pageNumber" default="1">
<cfset var recordsPerPage = 5>
<cfset var numberOfPages = Int(resultCount.RecordCount / recordsPerPage)>
<cfset var recordsToSkip = pageNumber * recordsPerPage - recordsPerPage>

<!---DEFINE LOCAL VARIABLE--->
<cfset var resultData = "">

<cfquery name="resultData" datasource="myDSN">
<!---GET DATA AND SEND IT BACK USING LIMIT WITH #recordsToSkip# and #RecordsPerPage#--->
</cfquery>
<!---RETURN VARIABLE--->
<cfreturn resultData>
</cffunction>

我想我会返回两个变量:resultCount和resultData.我会使用#resultCount#来构建我的分页,并使用#resultData#来显示输出.问题是我不能在同一个cfinvoke标签中返回两个变量.有关如何以正确的方式接近的任何想法？我完全迷失了我需要遵循的逻辑.

---

编辑:我现在使用以下代码进行分页(唯一的问题是现在我必须将所有搜索过滤器重新放回到URL中,因为使用#CGI.SCRIPT_NAME#清除它们):

<cfif searchResponse EQ "hasResult">
<!---BASICALLY, IF resultCount.rowsFound is not 0, execute this method--->
     <cfinvoke component="gz.cfcomp.test" method="getResult" returnvariable="resultData" argumentcollection="#URL#">

     <cfif URL.currentPage IS 1>
          --
     <cfelse>
          <a href="#CGI.SCRIPT_NAME#?searchQuery=&titleName=#URL.titleName#&genreID=#URL.genreID#&platformID=#URL.platformID#&currentPage=#currentPage-1#">Prev Page</a>
     </cfif>

     <cfif URL.currentPage * recordsPerPage LT resultCount.rowsFound>
          <a href="#CGI.SCRIPT_NAME#?searchQuery=&titleName=#URL.titleName#&genreID=#URL.genreID#&platformID=#URL.platformID#&currentPage=#currentPage+1#">Next Page</a>
     <cfelse>
          --
     </cfif>

</cfif>

Answer 1

如果结果不是很大,您可以使用返回所有内容并使用的相同SQL

<cfoutput query="data" startrow="#url.start#" maxrows="#recordsPerPage#">

当您显示它时,请参阅:http://www.coldfusionjedi.com/index.cfm/2006/4/24/ColdFusion-and-Pagination.不需要查询查询.

回答你的问题

问题是我不能在同一个cfinvoke标签中返回两个变量.

为什么要在同一个cfinvoke中返回两个变量？而是编写2个函数:countResult()和getResultData(page,RecordsPerPage)

<cffunction name="countResult" output="false" returntype="numeric">
  <cfset var resultCount = "">    
  <cfquery name="resultCount" datasource="myDSN">
    SELECT COUNT(gameID) AS rowsFound FROM GAMES
        <!---JOINS FOR GENRE/PLATFORM GO HERE--->
    WHERE
        <!---CONDITIONS GO HERE--->
  </cfquery>
  <cfreturn resultCount.rowsFound>
</cffunction>

对于使用DB级别的真实分页的getResultData(page,RecordsPerPage):

如果你想在数据库级别进行真正的pagnation LIMIT,请OFFSET在MySQL中使用.

<cffunction name="getResultData" output="false" returntype="Query">
  <cfargument name="page" type="numeric" default="1">
  <cfargument name="recordsPerPage" type="numeric" default="5">

  <cfset var resultData = "">
  <cfset var offset = (page-1) * RecordsPerPage>

  <cfquery name="resultData" datasource="myDSN">
    SELECT * LIMIT #recordsPerPage# OFFSET #offset#
        <!---JOINS FOR GENRE/PLATFORM GO HERE--->
    WHERE
        <!---CONDITIONS GO HERE--->
  </cfquery>

  <cfreturn resultData>
</cffunction>

要弄清楚有多少页:

totalNumOfPages = ceiling(countResult() / recordsPerPage);

还有其他问题吗？