142 lines
4.1 KiB
Go
142 lines
4.1 KiB
Go
package dbdrivers
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import (
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"database/sql"
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"fmt"
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// Import the postgres driver
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_ "github.com/lib/pq"
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)
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// PostgresDriver holds the database connection string and a handle
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// to the database connection.
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type PostgresDriver struct {
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connStr string
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dbConn *sql.DB
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}
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// NewPostgresDriver takes the database connection details as parameters and
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// returns a pointer to a PostgresDriver object. Note that it is required to
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// call PostgresDriver.Open() and PostgresDriver.Close() to open and close
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// the database connection once an object has been obtained.
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func NewPostgresDriver(user, pass, dbname, host string, port int) *PostgresDriver {
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driver := PostgresDriver{
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connStr: fmt.Sprintf("user=%s password=%s dbname=%s host=%s port=%d",
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user, pass, dbname, host, port),
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}
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return &driver
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}
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// Open opens the database connection using the connection string
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func (d *PostgresDriver) Open() error {
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var err error
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d.dbConn, err = sql.Open("postgres", d.connStr)
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if err != nil {
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return err
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}
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return nil
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}
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// Close closes the database connection
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func (d *PostgresDriver) Close() {
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d.dbConn.Close()
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}
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// GetAllTableNames connects to the postgres database and
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// retrieves all table names from the information_schema where the
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// table schema is public. It excludes common migration tool tables
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// such as gorp_migrations
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func (d *PostgresDriver) GetAllTableNames() ([]string, error) {
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var tableNames []string
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rows, err := d.dbConn.Query(`select table_name from
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information_schema.tables where table_schema='public'
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and table_name <> 'gorp_migrations'`)
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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for rows.Next() {
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var tableName string
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if err := rows.Scan(&tableName); err != nil {
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return nil, err
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}
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tableNames = append(tableNames, tableName)
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}
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return tableNames, nil
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}
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// GetTableInfo takes a table name and attempts to retrieve the table information
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// from the database information_schema.columns. It retrieves the column names
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// and column types and returns those as a []DBTable after ParseTableInfo()
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// converts the SQL types to Go types, for example: "varchar" to "string"
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func (d *PostgresDriver) GetTableInfo(tableName string) ([]DBTable, error) {
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var tableInfo []DBTable
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rows, err := d.dbConn.Query(`select column_name, data_type, is_nullable from
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information_schema.columns where table_name=$1`, tableName)
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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for rows.Next() {
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var colName, colType, isNullable string
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if err := rows.Scan(&colName, &colType, &isNullable); err != nil {
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return nil, err
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}
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tableInfo = append(tableInfo, d.ParseTableInfo(colName, colType, isNullable))
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}
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return tableInfo, nil
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}
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// ParseTableInfo converts postgres database types to Go types, for example
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// "varchar" to "string" and "bigint" to "int64". It returns this parsed data
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// as a DBTable object.
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func (d *PostgresDriver) ParseTableInfo(colName, colType, isNullable string) DBTable {
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t := DBTable{}
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t.ColName = colName
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if isNullable == "YES" {
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switch colType {
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case "bigint", "bigserial", "integer", "smallint", "smallserial", "serial":
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t.ColType = "null.Int"
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case "bit", "bit varying", "character", "character varying", "cidr", "inet", "json", "macaddr", "text", "uuid", "xml":
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t.ColType = "null.String"
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case "boolean":
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t.ColType = "null.Bool"
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case "date", "interval", "time", "timestamp without time zone", "timestamp with time zone":
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t.ColType = "null.Time"
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case "double precision", "money", "numeric", "real":
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t.ColType = "null.Float"
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default:
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t.ColType = "null.String"
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}
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} else {
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switch colType {
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case "bigint", "bigserial", "integer", "smallint", "smallserial", "serial":
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t.ColType = "int64"
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case "bit", "bit varying", "character", "character varying", "cidr", "inet", "json", "macaddr", "text", "uuid", "xml":
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t.ColType = "string"
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case "bytea":
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t.ColType = "[]byte"
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case "boolean":
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t.ColType = "bool"
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case "date", "interval", "time", "timestamp without time zone", "timestamp with time zone":
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t.ColType = "time.Time"
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case "double precision", "money", "numeric", "real":
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t.ColType = "float64"
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default:
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t.ColType = "string"
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}
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}
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return t
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}
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