postgresql - Need the ID of the current row inserted within a transaction -


within transaction i'm inserting row.

how can access , return id of inserted row. can see in code below(see under comment // return last inserted id.) tried use lastinsertedid() function, gives me error back.

btw, i'm using postgres.

what missing here? thx!

/**  * creates order , returns id.  */ func createorder(w http.responsewriter, r *http.request) (orderid int) {      // begin.     tx, err := db.begin()     if err != nil {         log.fatal(err)     }      // db query.     sqlquery := `insert order_customer         (customer_id)         values ($1)         returning id`      // prepare.     stmt, err := tx.prepare(sqlquery)     if err != nil {         log.fatal(err)         return     }      // defer close.     defer stmt.close()      customeremail := validatesession(r)     id := getidfromcustomer(customeremail)     order := order{}     order.customerid = id      // exec.     ret, err := stmt.exec(order.customerid)      // rollback.     if err != nil {         tx.rollback()         e := errors.new(err.error())         msg.warning = e.error()         tpl.executetemplate(w, "menu.gohtml", msg)         return     }      // return last inserted id.     lastid, err := ret.lastinsertid()     if err != nil {         orderid = 0     } else {         orderid = int(lastid)     }      // commit.     tx.commit()      return orderid } // createorder

here working solution now, further improvement welcomed.

/**  * creates order , returns id.  */ func createorder(w http.responsewriter, r *http.request) (orderid int) {      // begin.     tx, err := db.begin()     if err != nil {         log.fatal(err)     }      // db query.     sqlquery := `insert order_customer         (customer_id)         values ($1)         returning id`      // prepare.     stmt, err := tx.prepare(sqlquery)     if err != nil {         log.fatal(err)         return     }      // defer close.     defer stmt.close()      customeremail := validatesession(r)     id := getidfromcustomer(customeremail)     order := order{}     order.customerid = id      // exec.     _, err = stmt.exec(order.customerid)      // rollback.     if err != nil {         tx.rollback()         e := errors.new(err.error())         msg.warning = e.error()         tpl.executetemplate(w, "menu.gohtml", msg)         return     }      // return last inserted id.     //lastid, err := ret.lastinsertid()     err = stmt.queryrow(order.customerid).scan(&orderid)     if err != nil {         orderid = 0     }      // commit.     tx.commit()      return orderid } // createorder

this happens because postgresql driver using go doesn't supports lastinsertedid() function. didn't driver using have had issue working github.com/lib/pq.

the answer use queryrow insted of exec in original example. make sure using returning id on query , treat if select.

here example (i didn't test , might missing idea):

func createorder(w http.responsewriter, r *http.request) (orderid int) {      // begin.     tx, err := db.begin()     if err != nil {         log.fatal(err)     }      // db query.     sqlquery := `insert order_customer         (customer_id)         values ($1)         returning id`      // prepare.     stmt, err := tx.prepare(sqlquery)     if err != nil {         log.fatal(err)         return     }      // defer close.     defer stmt.close()      customeremail := validatesession(r)     id := getidfromcustomer(customeremail)     order := order{}     order.customerid = id      // exec.     var orderid int // or whatever type using     err := stmt.queryrow(order.customerid).scan(&orderid)      // rollback.     if err != nil {         //if goes wrong set orderid 0 in original code         orderid = 0         tx.rollback()         e := errors.new(err.error())         msg.warning = e.error()         tpl.executetemplate(w, "menu.gohtml", msg)         return     }      // commit.     tx.commit()      return orderid } // createorder

Comments

Post a Comment

Popular posts from this blog

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m...
Read more

python Tkinter Capturing keyboard events save as one single string -

is possible store keyboard events 1 string? code below stores 1 char , prints it. card reader or bar code reader, contains collection of character/ string not 1 character @ time. goal save char pressed text variable. from tkinter import * root = tk() def key(event): text= event.char text+= event.char print ("pressed", text) def callback(event): frame.focus_set() print ("clicked at", event.x, event.y) frame = frame(root, width=100, height=100) frame.bind("<key>", key) frame.bind("<button-1>", callback) frame.pack() root.mainloop() currently, creating text variable , everytime key() function gets called, , text stores last character typed. you can define text module level variable , , use module level text inside key function - text = '' def key(event): global text text+= event.char print("pressed", text)
Read more

sql server - Why does Linq-to-SQL add unnecessary COUNT()? -

here tables: create table customer ( cid int primary key, name varchar(32) ) create table ord ( oid int primary key, cid int foreign key references customer, address varchar(20) ) here's linq-to-sql statement: var aaa = c in db.customer select new { c, o = c.ord.tolist() }; and here's inexplicable query generated linq-to-sql: select [t0].[cid] [cid], [t0].[name] [name], [t1].[oid] [oid], [t1].[cid] [cid2], [t1].[address] [address], (select count(*) [dbo].[ord] [t2] [t2].[cid] = [t0].[cid]) [value] [dbo].[customer] [t0] left outer join [dbo].[ord] [t1] on [t1].[cid] = [t0].[cid] order [t0].[cid], [t1].[oid] i want understand how rid of count(*) part. it's entirely uncalled for! linq needs count(*) in order determine number of entries returned o = c.ord.tolist() .
Read more