Go开源项目 - gorp使用方法

# install the library:
go get github.com/coopernurse/gorp

// use in your .go code:
import (
    "github.com/coopernurse/gorp"
)

# Set env variable with dsn using mymysql format.  From the mymysql docs, 
# the format can be of 3 types:
#
#    DBNAME/USER/PASSWD
#    unix:SOCKPATH*DBNAME/USER/PASSWD
#    tcp:ADDR*DBNAME/USER/PASSWD
#
# for example, on my box I use:
export GORP_TEST_DSN=gomysql_test/gomysql_test/abc123

# run the tests
go test

# run the tests and benchmarks
go test -bench="Bench" -benchtime 10

type Invoice struct {
    Id       int64
    Created  int64
    Updated  int64
    Memo     string
    PersonId int64
}

type Person struct {
    Id      int64    
    Created int64
    Updated int64
    FName   string
    LName   string
}

// Example of using tags to alias fields to column names
// The 'db' value is the column name
//
// A hyphen will cause gorp to skip this field, similar to the
// Go json package.
//
// This is equivalent to using the ColMap methods:
//
//   table := dbmap.AddTableWithName(Product{}, "product")
//   table.ColMap("Id").Rename("product_id")
//   table.ColMap("Price").Rename("unit_price")
//   table.ColMap("IgnoreMe").SetTransient(true)
//
type Product struct {
    Id         int64     `db:"product_id"`
    Price      int64     `db:"unit_price"`
    IgnoreMe   string    `db:"-"`
}

// connect to db using standard Go database/sql API
// use whatever database/sql driver you wish
db, err := sql.Open("mymysql", "tcp:localhost:3306*mydb/myuser/mypassword")

// construct a gorp DbMap
dbmap := &gorp.DbMap{Db: db, Dialect: gorp.MySQLDialect{"InnoDB", "UTF8"}}

// register the structs you wish to use with gorp
// you can also use the shorter dbmap.AddTable() if you 
// don't want to override the table name
//
// SetKeys(true) means we have a auto increment primary key, which
// will get automatically bound to your struct post-insert
//
t1 := dbmap.AddTableWithName(Invoice{}, "invoice_test").SetKeys(true, "Id")
t2 := dbmap.AddTableWithName(Person{}, "person_test").SetKeys(true, "Id")
t3 := dbmap.AddTableWithName(Product{}, "product_test").SetKeys(true, "Id")

// create all registered tables
dbmap.CreateTables()

// drop
dbmap.DropTables()

// Will log all SQL statements + args as they are run
// The first arg is a string prefix to prepend to all log messages
dbmap.TraceOn("[gorp]", log.New(os.Stdout, "myapp:", log.Lmicroseconds)) 

// Turn off tracing
dbmap.TraceOff()

// Must declare as pointers so optional callback hooks
// can operate on your data, not copies
inv1 := &Invoice{0, 100, 200, "first order", 0}
inv2 := &Invoice{0, 100, 200, "second order", 0}

// Insert your rows
err := dbmap.Insert(inv1, inv2)

// Because we called SetKeys(true) on Invoice, the Id field
// will be populated after the Insert() automatically
fmt.Printf("inv1.Id=%d  inv2.Id=%d\n", inv1.Id, inv2.Id)

res, err := dbmap.Exec("delete from invoice_test where PersonId=?", 10)

// Define a type for your join
// It *must* contain all the columns in your SELECT statement
//
// The names here should match the aliased column names you specify
// in your SQL - no additional binding work required.  simple.
//
type InvoicePersonView struct {
    InvoiceId   int64
    PersonId    int64
    Memo        string
    FName       string
}

// Create some rows
p1 := &Person{0, 0, 0, "bob", "smith"}
dbmap.Insert(p1)

// notice how we can wire up p1.Id to the invoice easily
inv1 := &Invoice{0, 0, 0, "xmas order", p1.Id}
dbmap.Insert(inv1)

// Run your query
query := "select i.Id InvoiceId, p.Id PersonId, i.Memo, p.FName " +
    "from invoice_test i, person_test p " +
    "where i.PersonId = p.Id"
list, err := dbmap.Select(InvoicePersonView{}, query)

// this should test true
expected := &InvoicePersonView{inv1.Id, p1.Id, inv1.Memo, p1.FName}
if reflect.DeepEqual(list[0], expected) {
    fmt.Println("Woot! My join worked!")
}

func InsertInv(dbmap *DbMap, inv *Invoice, per *Person) error {
    // Start a new transaction
    trans := dbmap.Begin()

    trans.Insert(per)
    inv.PersonId = per.Id
    trans.Insert(inv)

    // if the commit is successful, a nil error is returned
    return trans.Commit()
}

// implement the PreInsert and PreUpdate hooks
func (i *Invoice) PreInsert(s gorp.SqlExecutor) error {
    i.Created = time.Now().UnixNano()
    i.Updated = i.Created
    return nil
}

func (i *Invoice) PreUpdate(s gorp.SqlExecutor) error {
    i.Updated = time.Now().UnixNano()
    return nil
}

// You can use the SqlExecutor to cascade additional SQL
// Take care to avoid cycles. gorp won't prevent them.
//
// Here's an example of a cascading delete
//
func (p *Person) PreDelete(s gorp.SqlExecutor) error {
    query := "delete from invoice_test where PersonId=?"
    err := s.Exec(query, p.Id); if err != nil {
        return err
    }
    return nil
}

PostGet
PreInsert
PostInsert
PreUpdate
PostUpdate
PreDelete
PostDelete

All have the same signature.  for example:

func (p *MyStruct) PostUpdate(s gorp.SqlExecutor) error

// Version is an auto-incremented number, managed by gorp
// If this property is present on your struct, update
// operations will be constrained
//
// For example, say we defined Person as:

type Person struct {
    Id       int64
    Created  int64
    Updated  int64
    FName    string
    LName    string

    // automatically used as the Version col
    // use table.SetVersionCol("columnName") to map a different
    // struct field as the version field
    Version  int64
}

p1 := &Person{0, 0, 0, "Bob", "Smith", 0}
dbmap.Insert(p1)  // Version is now 1

obj, err := dbmap.Get(Person{}, p1.Id)
p2 := obj.(*Person)
p2.LName = "Edwards"
dbmap.Update(p2)  // Version is now 2

p1.LName = "Howard"

// Raises error because p1.Version == 1, which is out of date
count, err := dbmap.Update(p1)
_, ok := err.(gorp.OptimisticLockError)
if ok {
    // should reach this statement

    // in a real app you might reload the row and retry, or
    // you might propegate this to the user, depending on the desired
    // semantics
    fmt.Printf("Tried to update row with stale data: %v\n", err)
} else {
    // some other db error occurred - log or return up the stack
    fmt.Printf("Unknown db err: %v\n", err)
}