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Ejemplo: aplicación Go App Engine
Este ejemplo es una aplicación de App Engine, escrita en Go, que proporciona una interfaz web que usa Bigtable para hacer un seguimiento de la cantidad de visitas de tu Cuenta de Google. Se ejecuta en un contenedor de Docker local o en la nube, en el entorno flexible de App Engine. El código de esta aplicación se encuentra en el repositorio de GitHub GoogleCloudPlatform/golang-samples, en el directorio bigtable/usercounter.
Descripción general del código de muestra
Cuando se inicia el código de muestra, se crea un cliente administrativo para Bigtable. Luego, usa el cliente a fin de comprobar la instancia de Bigtable especificada por el usuario para una tabla llamada user-visit-counter, con una sola familia de columnas denominada emails. Si es necesario, crea la tabla y la familia de columnas:
adminClient,err:=bigtable.NewAdminClient(ctx,project,instance)iferr!=nil{log.Fatalf("Unable to create a table admin client. %v",err)}tables,err:=adminClient.Tables(ctx)iferr!=nil{log.Fatalf("Unable to fetch table list. %v",err)}if!sliceContains(tables,tableName){iferr:=adminClient.CreateTable(ctx,tableName);err!=nil{log.Fatalf("Unable to create table: %v. %v",tableName,err)}}tblInfo,err:=adminClient.TableInfo(ctx,tableName)iferr!=nil{log.Fatalf("Unable to read info for table: %v. %v",tableName,err)}if!sliceContains(tblInfo.Families,familyName){iferr:=adminClient.CreateColumnFamily(ctx,tableName,familyName);err!=nil{log.Fatalf("Unable to create column family: %v. %v",familyName,err)}}adminClient.Close()
Luego, el código de muestra crea un solo cliente de Bigtable que se use para todas las lecturas y escrituras posteriores:
client,err=bigtable.NewClient(ctx,project,instance)iferr!=nil{log.Fatalf("Unable to create data operations client. %v",err)}
Por último, el código de muestra agrega un controlador HTTP a la raíz del servidor de App Engine. En cada solicitud, el controlador le pide al usuario que acceda a su cuenta si es necesario. Luego, realiza un seguimiento de la visita del usuario mediante una operación Increment en la fila de la dirección de correo electrónico del usuario:
tbl:=client.Open(tableName)rmw:=bigtable.NewReadModifyWrite()rmw.Increment(familyName,u.Email,1)row,err:=tbl.ApplyReadModifyWrite(ctx,u.Email,rmw)iferr!=nil{return&appError{err,"Error applying ReadModifyWrite to row: "+u.Email,http.StatusInternalServerError}}
Después de aumentar la fila, el controlador muestra una página HTML en la que aparece la cantidad total de visitas del usuario actual.
[[["Fácil de comprender","easyToUnderstand","thumb-up"],["Resolvió mi problema","solvedMyProblem","thumb-up"],["Otro","otherUp","thumb-up"]],[["Difícil de entender","hardToUnderstand","thumb-down"],["Información o código de muestra incorrectos","incorrectInformationOrSampleCode","thumb-down"],["Faltan la información o los ejemplos que necesito","missingTheInformationSamplesINeed","thumb-down"],["Problema de traducción","translationIssue","thumb-down"],["Otro","otherDown","thumb-down"]],["Última actualización: 2025-09-09 (UTC)"],[[["\u003cp\u003eThis is a Go-based App Engine application that uses Bigtable to track the number of visits from each user's Google account.\u003c/p\u003e\n"],["\u003cp\u003eThe application can be run locally in a Docker container or in the cloud within App Engine's flexible environment.\u003c/p\u003e\n"],["\u003cp\u003eUpon launch, the code creates a Bigtable administrative client to manage the \u003ccode\u003euser-visit-counter\u003c/code\u003e table and its \u003ccode\u003eemails\u003c/code\u003e column family, creating them if they don't exist.\u003c/p\u003e\n"],["\u003cp\u003eThe application uses a Bigtable client for reads and writes, and it includes an HTTP handler that prompts users to log in and then increments their visit count in Bigtable.\u003c/p\u003e\n"],["\u003cp\u003eThe app does not provide any access control for the user data and should be shutdown after testing.\u003c/p\u003e\n"]]],[],null,["Example: Go App Engine Application\n\nThis example is an [App Engine](/appengine) application, written in Go, that\nprovides a web interface that uses Bigtable to track the number of\nvisits from your Google account. It runs locally in a Docker container or in the\ncloud in App Engine's [flexible environment](/appengine/docs/flexible). The code for\nthis application is in the GitHub repository\n[GoogleCloudPlatform/golang-samples](https://github.com/GoogleCloudPlatform/golang-samples), in the directory\n`bigtable/usercounter`.\n| **Warning:** This application does not provide any access control for your data. Shut down the application when you are done testing.\n\nOverview of the code sample\n\nWhen the code sample is launched, it creates an administrative client for\nBigtable. It then uses the client to check the user-specified\nBigtable instance for a table named `user-visit-counter`, with a\nsingle column family named `emails`. If necessary, it creates the table and\ncolumn family: \n\n adminClient, err := bigtable.NewAdminClient(ctx, project, instance)\n if err != nil {\n \tlog.Fatalf(\"Unable to create a table admin client. %v\", err)\n }\n tables, err := adminClient.Tables(ctx)\n if err != nil {\n \tlog.Fatalf(\"Unable to fetch table list. %v\", err)\n }\n if !sliceContains(tables, tableName) {\n \tif err := adminClient.CreateTable(ctx, tableName); err != nil {\n \t\tlog.Fatalf(\"Unable to create table: %v. %v\", tableName, err)\n \t}\n }\n tblInfo, err := adminClient.TableInfo(ctx, tableName)\n if err != nil {\n \tlog.Fatalf(\"Unable to read info for table: %v. %v\", tableName, err)\n }\n if !sliceContains(tblInfo.Families, familyName) {\n \tif err := adminClient.CreateColumnFamily(ctx, tableName, familyName); err != nil {\n \t\tlog.Fatalf(\"Unable to create column family: %v. %v\", familyName, err)\n \t}\n }\n adminClient.Close()\n\nThe code sample then creates a single Bigtable client that is used\nfor all subsequent reads and writes: \n\n client, err = bigtable.NewClient(ctx, project, instance)\n if err != nil {\n \tlog.Fatalf(\"Unable to create data operations client. %v\", err)\n }\n\nFinally, the code sample adds an HTTP handler to the root of the App Engine\nserver. On each request, the handler prompts the user to log in if necessary. It\nthen tracks the user's visit by performing an `Increment` operation on the row\nfor the user's email address: \n\n tbl := client.Open(tableName)\n rmw := bigtable.NewReadModifyWrite()\n rmw.Increment(familyName, u.Email, 1)\n row, err := tbl.ApplyReadModifyWrite(ctx, u.Email, rmw)\n if err != nil {\n \treturn &appError{err, \"Error applying ReadModifyWrite to row: \" + u.Email, http.StatusInternalServerError}\n }\n\nAfter incrementing the row, the handler displays an HTML page showing the total\nnumber of visits by the current user."]]