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This article is about how to understand the select two-level linkage query, the editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

When writing a fault management system, we need to use select two-level linkage query to search for faults according to the main class-platform.

Front-end html

Please select the main class {% for val in search%} {{val}} {% endfor%} Please select the platform search $(document) .ready (function () {$('# se_program') .change (function () {se_program = $('# se_program'). Val ()) Data = {se_program: se_program}; $.ajax ({url: "/ liandong/", data:data, type:'post', success: function (platform) {$("# se_platform") .empty () $("# se_platform") .append ("" + "Please select platform" + "); $.each (platform,function (I) {$(" # se_platform ") .append ("+ platform [I] +")}))

Django backend view

Def search (request,page): "" search view, receive the main class name from the front end, match the database to get the data, and return it to the front end. Custom paging "" check_Program=request.GET ['Program'] check_PlatForm=request.GET [' PlatForm'] check_Program=check_Program.encode ("utf-8") check_PlatForm=check_PlatForm.encode ("utf-8") if check_Program= = 'test_program': return HttpResponseRedirect (' / index/') if check_Program! = 'test_program' and check_PlatForm=='test_platform': Ch_result = FaultReports.objects.filter (Program = check_Program) plat=FaultReports.objects.values_list ('PlatForm' Flat=True) .filter (Program = check_Program) plat=set (plat) if ch_result: islogin=False page=gb001.try_int (page, 1) totalitems=FaultReports.objects.filter (Program = check_Program). Count () pageInofobj=html.PageInfo (page,totalitems) pager=html.Search_Program_page ('/ search/',page,pageInofobj.TotalPage () Check_Program) all_data=FaultReports.objects.filter (Program = check_Program). Order_by ("- id") [pageInofobj.From (): pageInofobj.To ()] data=FaultReports.objects.values_list ("Program", flat=True) data=set (data) try: islogin=request.session ['islogin'] except Exception E: pass if islogin: name = request.session ['username'] return render_to_response (' search.html', {'login_user':name,'pager':pager,'result':all_data,'search':data,'query':check_Program 'plat':plat}) else: return HttpResponseRedirect (' / login/') else: ch_result = FaultReports.objects.filter (Program = check_Program,PlatForm=check_PlatForm) plat=FaultReports.objects.values_list ('PlatForm',flat=True) .filter (Program = check_Program) plat=set (plat) print plat if ch_result: islogin=False page=gb001.try_int (page 1) totalitems=FaultReports.objects.filter (Program = check_Program,PlatForm=check_PlatForm). Count () pageInofobj=html.PageInfo (page,totalitems) pager=html.Search_Program_page ('/ search/',page,pageInofobj.TotalPage (), check_Program,check_PlatForm) all_data=FaultReports.objects.filter (Program = check_Program) PlatForm=check_PlatForm) .order_by ("- id") [pageInofobj.From (): pageInofobj.To ()] data=FaultReports.objects.values_list ("Program", flat=True) data=set (data) try: islogin=request.session ['islogin'] except Exception E: pass if islogin: name = request.session ['username'] return render_to_response (' search.html', {'login_user':name,'pager':pager,'result':all_data,'search':data,'query':check_Program,'query_platform':check_PlatForm 'plat':plat}) else: return HttpResponseRedirect (' / login/') def liandong (request): if request.method = = 'POST': data=request.POST.get (' se_program') print request.POST PlatFormList= [] contents = FaultReports.objects.filter (Program=data) for line in contents: if PlatFormList.count (line.PlatForm) = 0: PlatFormList.append (line.PlatForm) platform= PlatFormList # platform=set (platform) # print platform return HttpResponse (json.dumps (platform) Content_type= "application/json") above is how to understand the select two-level linkage query The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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