# README

GORM

Driver

go get gorm.io/gorm@latest

Transaction Retry Support

https://github.com/cockroachdb/cockroach-go/tree/master/crdb/crdbgorm

Bank Example

Covered steps:

Use GORM to map Go-specific objects to SQL operations.
Use crdbgorm package to handle transactions. Specifically:
- db.AutoMigrate(&Account{}) creates an accounts table based on the Account model.
- db.Create(&Account{}) inserts rows into the table.
- db.Find(&accounts) selects from the table so that balances can be printed.
- Transfer funds transferFunds().
- Handle retry errors crdbgorm.ExecuteTx().

Note that CockroachDB may require the client to retry a transaction in the case of read/write contention.

CREATE DATABASE bank;
CREATE USER johndoe WITH PASSWORD gopher;
GRANT ALL ON DATABASE bank TO johndoe;
-- DROP DATABASE bank CASCADE;

GORM

import (
	"github.com/cockroachdb/cockroach-go/v2/crdb/crdbgorm"
	"gorm.io/driver/postgres"
	"gorm.io/gorm"
)

go build .

DATABASE_URL='postgresql://johndoe@localhost:26257/bank?sslmode=disable' ./gorm

2022/07/06 13:13:13 Creating 5 new accounts...
2022/07/06 13:13:13 Accounts created.
Balance at '2022-07-06 13:13:13.542826662 +0200 CEST m=+0.151700383':
a3869d47-eeda-4e4c-9564-7ddfc5ac0868 4159
c22bfbe2-3dcc-495c-b89e-410cef601168 7987
d205f242-dec4-481c-a5e6-ac83b1d763ee 2181
dc35d3f6-617c-417e-ae21-2b98dc62a90d 8181
f5eedc33-c059-4a71-b51c-72acfc3b3f39 1947
2022/07/06 13:13:13 Transferring 100 from account dc35d3f6-617c-417e-ae21-2b98dc62a90d to account d205f242-dec4-481c-a5e6-ac83b1d763ee...
2022/07/06 13:13:13 Funds transferred.
Balance at '2022-07-06 13:13:13.554112895 +0200 CEST m=+0.162986613':
a3869d47-eeda-4e4c-9564-7ddfc5ac0868 4159
c22bfbe2-3dcc-495c-b89e-410cef601168 7987
d205f242-dec4-481c-a5e6-ac83b1d763ee 2281
dc35d3f6-617c-417e-ae21-2b98dc62a90d 8081
f5eedc33-c059-4a71-b51c-72acfc3b3f39 1947
2022/07/06 13:13:13 Deleting accounts created...
2022/07/06 13:13:13 Accounts deleted.