Documentation ¶
Overview ¶
Package sqlstruct provides some convenience functions for using structs with the Go standard library's database/sql package.
The package matches struct field names to SQL query column names. A field can also specify a matching column with "sql" tag, if it's different from field name. Unexported fields or fields marked with `sql:"-"` are ignored, just like with "encoding/json" package.
For example:
type T struct { F1 string F2 string `sql:"field2"` F3 string `sql:"-"` } rows, err := db.Query(fmt.Sprintf("SELECT %s FROM tablename", sqlstruct.Columns(T{}))) ... for rows.Next() { var t T err = sqlstruct.Scan(&t, rows) ... } err = rows.Err() // get any errors encountered during iteration
Aliased tables in a SQL statement may be scanned into a specific structure identified by the same alias, using the ColumnsAliased and ScanAliased functions:
type User struct { Id int `sql:"id"` Username string `sql:"username"` Email string `sql:"address"` Name string `sql:"name"` HomeAddress *Address `sql:"-"` } type Address struct { Id int `sql:"id"` City string `sql:"city"` Street string `sql:"address"` } ... var user User var address Address sql := `
SELECT %s, %s FROM users AS u INNER JOIN address AS a ON a.id = u.address_id WHERE u.username = ? `
sql = fmt.Sprintf(sql, sqlstruct.ColumnsAliased(*user, "u"), sqlstruct.ColumnsAliased(*address, "a")) rows, err := db.Query(sql, "gedi") if err != nil { log.Fatal(err) } defer rows.Close() if rows.Next() { err = sqlstruct.ScanAliased(&user, rows, "u") if err != nil { log.Fatal(err) } err = sqlstruct.ScanAliased(&address, rows, "a") if err != nil { log.Fatal(err) } user.HomeAddress = address } fmt.Printf("%+v", *user) // output: "{Id:1 Username:gedi Email:gediminas.morkevicius@gmail.com Name:Gedas HomeAddress:0xc21001f570}" fmt.Printf("%+v", *user.HomeAddress) // output: "{Id:2 City:Vilnius Street:Plento 34}"
Index ¶
Constants ¶
This section is empty.
Variables ¶
var NameMapper = strings.ToLower
NameMapper is used to convert struct fields which do not have sql tags into database column names. The default mapper is a no-op.
Example override usage:
FirstName => first_name sqlstruct.NameMapper = sqlstruct.ToSnakeCase Any func(string)string can be used
Functions ¶
func Columns ¶
func Columns(s interface{}) string
Columns returns a string containing a sorted, comma-separated list of column names as defined by the type s. s must be a struct that has exported fields tagged with the "sql" tag.
func ColumnsAliased ¶
ColumnsAliased works like Columns except it prefixes the resulting column name with the given alias.
For each field in the given struct it will generate a statement like:
alias.field AS alias_field
It is intended to be used in conjunction with the ScanAliased function.
func Scan ¶
Scan scans the next row from rows in to a struct pointed to by dest. The struct type should have exported fields tagged with the "sql" tag. Columns from row which are not mapped to any struct fields are ignored. Struct fields which have no matching column in the result set are left unchanged.
func ScanAliased ¶
ScanAliased works like scan, except that it expects the results in the query to be prefixed by the given alias.
For example, if scanning to a field named "name" with an alias of "user" it will expect to find the result in a column named "user_name".
See ColumnAliased for a convenient way to generate these queries.