外文翻译 英文文献 使用两个DropDownList过滤的主从报表.docx

外文翻译 英文文献 使用两个DropDownList过滤的主从报表.docx

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外文翻译英文文献使用两个DropDownList过滤的主从报表

Master/DetailFilteringWithTwoDropDownLists

Introduction

Intheprevioustutorialweexaminedhowtodisplayasimplemaster/detailsreportusingasingleDropDownListpopulatedwiththecategoriesandaGridViewshowingthoseproductsthatbelongtotheselectedcategory.Thisreportpatternworkswellwhendisplayingrecordsthathaveaone-to-manyrelationshipandcaneasilybeextendedtoworkforscenariosthatincludemultipleone-to-manyrelationships.Forexample,anorderentrysystemwouldhavetablesthatcorrespondtocustomers,orders,andorderlineitems.Agivencustomermayhavemultipleorderswitheachorderconsistingofmultipleitems.SuchdatacanbepresentedtotheuserwithtwoDropDownListsandaGridView.ThefirstDropDownListwouldhavealistitemforeachcustomerinthedatabasewiththesecondone'scontentsbeingtheordersplacedbytheselectedcustomer.AGridViewwouldlistthelineitemsfromtheselectedorder.

WhiletheNorthwinddatabaseincludethecanonicalcustomer/order/orderdetailsinformationinitsCustomers,Orders,andOrderDetailstables,thesetablesaren'tcapturedinourarchitecture.Nonetheless,wecanstillillustrateusingtwodependentDropDownLists.ThefirstDropDownListwilllistthecategoriesandthesecondtheproductsbelongingtotheselectedcategory.ADetailsViewwillthenlistthedetailsoftheselectedproduct.

Step1:

CreatingandPopulatingtheCategoriesDropDownList

OurfirstgoalistoaddtheDropDownListthatliststhecategories.Thesestepswereexaminedindetailintheprecedingtutorial,butaresummarizedhereforcompleteness.

OpentheMasterDetailsDetails.aspxpageintheFilteringfolder,addaDropDownListtothepage,setitsIDpropertytoCategories,andthenclicktheConfigureDataSourcelinkinitssmarttag.FromtheDataSourceConfigurationWizardchoosetoaddanewdatasource.

Figure1:

AddaNewDataSourcefortheDropDownList（Clicktoviewfull-sizeimage）

Thenewdatasourceshould,naturally,beanObjectDataSource.NamethisnewObjectDataSourceCategoriesDataSourceandhaveitinvoketheCategoriesBLLobject'sGetCategories（）method.

Figure2:

ChoosetoUsetheCategoriesBLLClass（Clicktoviewfull-sizeimage）

Figure3:

ConfiguretheObjectDataSourcetoUsetheGetCategories（）Method（Clicktoviewfull-sizeimage）

AfterconfiguringtheObjectDataSourcewestillneedtospecifywhichdatasourcefieldshouldbedisplayedintheCategoriesDropDownListandwhichoneshouldbeconfiguredasthevalueforthelistitem.SettheCategoryNamefieldasthedisplayandCategoryIDasthevalueforeachlistitem.

Figure4:

HavetheDropDownListDisplaytheCategoryNameFieldandUseCategoryIDastheValue（Clicktoviewfull-sizeimage）

AtthispointwehaveaDropDownListcontrol（Categories）that'spopulatedwiththerecordsfromtheCategoriestable.WhentheuserchoosesanewcategoryfromtheDropDownListwe'llwantapostbacktooccurinordertorefreshtheproductDropDownListthatwe'regoingtocreateinStep2.Therefore,checktheEnableAutoPostBackoptionfromthecategoriesDropDownList'ssmarttag.

Figure5:

EnableAutoPostBackfortheCategoriesDropDownList（Clicktoviewfull-sizeimage）

Step2:

DisplayingtheSelectedCategory'sProductsinaSecondDropDownList

WiththeCategoriesDropDownListcompleted,ournextstepistodisplayaDropDownListofproductsbelongingtotheselectedcategory.Toaccomplishthis,addanotherDropDownListtothepagenamedProductsByCategory.AswiththeCategoriesDropDownList,createanewObjectDataSourcefortheProductsByCategoryDropDownListnamedProductsByCategoryDataSource.

Figure6:

AddaNewDataSourcefortheProductsByCategoryDropDownList（Clicktoviewfull-sizeimage）

Figure7:

CreateaNewObjectDataSourceNamedProductsByCategoryDataSource（Clicktoviewfull-sizeimage）

SincetheProductsByCategoryDropDownListneedstodisplayjustthoseproductsbelongingtotheselectedcategory,havetheObjectDataSourceinvoketheGetProductsByCategoryID（categoryID）methodfromtheProductsBLLobject.

Figure8:

ChoosetoUsetheProductsBLLClass（Clicktoviewfull-sizeimage）

Figure9:

ConfiguretheObjectDataSourcetoUsetheGetProductsByCategoryID（categoryID）Method（Clicktoviewfull-sizeimage）

InthefinalstepofthewizardweneedtospecifythevalueofthecategoryIDparameter.AssignthisparametertotheselecteditemfromtheCategoriesDropDownList.

Figure10:

PullthecategoryIDParameterValuefromtheCategoriesDropDownList（Clicktoviewfull-sizeimage）

WiththeObjectDataSourceconfigured,allthatremainsistospecifywhatdatasourcefieldsareusedforthedisplayandvalueoftheDropDownList'sitems.DisplaytheProductNamefieldandusetheProductIDfieldasthevalue.

Figure11:

SpecifytheDataSourceFieldsUsedforth