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Example: Go App Engine Application
This example is an App Engine application, written in Go, that
provides a web interface that uses Bigtable to track the number of
visits from your Google account. It runs locally in a Docker container or in the
cloud in App Engine's flexible environment. The code for
this application is in the GitHub repository
GoogleCloudPlatform/golang-samples, in the directory
bigtable/usercounter.
Overview of the code sample
When the code sample is launched, it creates an administrative client for
Bigtable. It then uses the client to check the user-specified
Bigtable instance for a table named user-visit-counter, with a
single column family named emails. If necessary, it creates the table and
column family:
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()
The code sample then creates a single Bigtable client that is used
for all subsequent reads and writes:
client,err=bigtable.NewClient(ctx,project,instance)iferr!=nil{log.Fatalf("Unable to create data operations client. %v",err)}
Finally, the code sample adds an HTTP handler to the root of the App Engine
server. On each request, the handler prompts the user to log in if necessary. It
then tracks the user's visit by performing an Increment operation on the row
for the user's email address:
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}}
After incrementing the row, the handler displays an HTML page showing the total
number of visits by the current user.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 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."]]