v/vlib/pg/pg.v

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module pg
#flag -lpq
#flag linux -I/usr/include/postgresql
#flag darwin -I/opt/local/include/postgresql11
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#flag windows -I @VROOT/thirdparty/pg/include
#flag windows -L @VROOT/thirdparty/pg/win64
#include <libpq-fe.h>
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pub struct DB {
mut:
conn &C.PGconn
}
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pub struct Row {
pub mut:
vals []string
}
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struct C.PGResult
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pub struct Config {
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pub:
host string
port int = 5432
user string
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password string
dbname string
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}
fn C.PQconnectdb(a byteptr) &C.PGconn
fn C.PQerrorMessage(voidptr) byteptr
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fn C.PQgetvalue(&C.PGResult, int, int) byteptr
fn C.PQstatus(voidptr) int
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fn C.PQresultStatus(voidptr) int
fn C.PQntuples(&C.PGResult) int
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fn C.PQnfields(&C.PGResult) int
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fn C.PQexec(voidptr) &C.PGResult
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fn C.PQexecParams(voidptr) &C.PGResult
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fn C.PQclear(&C.PGResult) voidptr
fn C.PQfinish(voidptr)
// connect makes a new connection to the database server using
// the parameters from the `Config` structure, returning
// a connection error when something goes wrong
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pub fn connect(config Config) ?DB {
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conninfo := 'host=$config.host port=$config.port user=$config.user dbname=$config.dbname password=$config.password'
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conn := C.PQconnectdb(conninfo.str)
if conn == 0 {
return error('libpq memory allocation error')
}
status := C.PQstatus(conn)
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if status != C.CONNECTION_OK {
// We force the construction of a new string as the
// error message will be freed by the next `PQfinish`
// call
c_error_msg := unsafe {C.PQerrorMessage(conn).vstring()}
error_msg := '$c_error_msg'
C.PQfinish(conn)
return error('Connection to a PG database failed: $error_msg')
}
return DB{
conn: conn
}
}
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fn res_to_rows(res voidptr) []Row {
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nr_rows := C.PQntuples(res)
nr_cols := C.PQnfields(res)
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mut rows := []Row{}
for i in 0 .. nr_rows {
mut row := Row{}
for j in 0 .. nr_cols {
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val := C.PQgetvalue(res, i, j)
sval := unsafe {val.vstring()}
row.vals << sval
}
rows << row
}
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C.PQclear(res)
return rows
}
// close frees the underlaying resource allocated by the database connection
pub fn (db DB) close() {
C.PQfinish(db.conn)
}
// q_int submit a command to the database server and
// returns an the first field in the first tuple
// converted to an int. If no row is found or on
// command failure, an error is returned
pub fn (db DB) q_int(query string) ?int {
rows := db.exec(query) ?
if rows.len == 0 {
return error('q_int "$query" not found')
}
row := rows[0]
if row.vals.len == 0 {
return 0
}
val := row.vals[0]
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return val.int()
}
// q_int submit a command to the database server and
// returns an the first field in the first tuple
// as a string. If no row is found or on
// command failure, an error is returned
pub fn (db DB) q_string(query string) ?string {
rows := db.exec(query) ?
if rows.len == 0 {
return error('q_string "$query" not found')
}
row := rows[0]
if row.vals.len == 0 {
return ''
}
val := row.vals[0]
return val
}
// q_strings submit a command to the database server and
// returns the resulting row set. Alias of `exec`
pub fn (db DB) q_strings(query string) ?[]Row {
return db.exec(query)
}
// exec submit a command to the database server and wait
// for the result, returning an error on failure and a
// row set on success
pub fn (db DB) exec(query string) ?[]Row {
res := C.PQexec(db.conn, query.str)
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return db.handle_error_or_result(res, 'exec')
}
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fn rows_first_or_empty(rows []Row) ?Row {
if rows.len == 0 {
return error('no row')
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}
return rows[0]
}
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pub fn (db DB) exec_one(query string) ?Row {
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res := C.PQexec(db.conn, query.str)
e := unsafe {C.PQerrorMessage(db.conn).vstring()}
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if e != '' {
return error('pg exec error: "$e"')
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}
row := rows_first_or_empty(res_to_rows(res)) ?
return row
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}
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// exec_param_many executes a query with the provided parameters
pub fn (db DB) exec_param_many(query string, params []string) ?[]Row {
mut param_vals := []charptr{ len: params.len }
for i in 0 .. params.len {
param_vals[i] = params[i].str
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}
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res := C.PQexecParams(db.conn, query.str, params.len, 0, param_vals.data, 0, 0, 0)
return db.handle_error_or_result(res, 'exec_param_many')
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}
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pub fn (db DB) exec_param2(query string, param string, param2 string) ?[]Row {
return db.exec_param_many(query, [param, param2])
}
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pub fn (db DB) exec_param(query string, param string) ?[]Row {
return db.exec_param_many(query, [param])
}
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fn (db DB) handle_error_or_result(res voidptr, elabel string) ?[]Row {
e := unsafe {C.PQerrorMessage(db.conn).vstring()}
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if e != '' {
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C.PQclear(res)
return error('pg $elabel error:\n$e')
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}
return res_to_rows(res)
}