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
}
struct C.PGResult { }
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pub struct Config {
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pub:
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host string
port int = 5432
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user string
password string
dbname string
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}
fn C.PQconnectdb(a byteptr) &C.PGconn
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fn C.PQerrorMessage(voidptr) byteptr
fn C.PQgetvalue(voidptr, int, int) byteptr
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fn C.PQstatus(voidptr) int
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fn C.PQntuples(voidptr) int
fn C.PQnfields(voidptr) int
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fn C.PQexec(voidptr) voidptr
fn C.PQexecParams(voidptr) voidptr
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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=$config.password'
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conn := C.PQconnectdb(conninfo.str)
status := C.PQstatus(conn)
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println("status=$status")
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if status != C.CONNECTION_OK {
error_msg := C.PQerrorMessage(conn)
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return error ('Connection to a PG database failed: ' + string(error_msg))
}
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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)
row.vals << string(val)
}
rows << row
}
return rows
}
pub fn (db DB) q_int(query string) int {
rows := db.exec(query)
if rows.len == 0 {
println('q_int "$query" not found')
return 0
}
row := rows[0]
if row.vals.len == 0 {
return 0
}
val := row.vals[0]
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return val.int()
}
pub fn (db DB) q_string(query string) string {
rows := db.exec(query)
if rows.len == 0 {
println('q_string "$query" not found')
return ''
}
row := rows[0]
if row.vals.len == 0 {
return ''
}
val := row.vals[0]
return val
}
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pub fn (db DB) q_strings(query string) []Row {
return db.exec(query)
}
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pub fn (db DB) exec(query string) []Row {
res := C.PQexec(db.conn, query.str)
e := string(C.PQerrorMessage(db.conn))
if e != '' {
println('pg exec error:')
println(e)
return res_to_rows(res)
}
return res_to_rows(res)
}
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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 := string(C.PQerrorMessage(db.conn))
if e != '' {
return error('pg exec error: "$e"')
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}
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row := rows_first_or_empty( res_to_rows(res) ) or { return error(err) }
return row
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}
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// The entire function can be considered unsafe because of the malloc and the
// free. This prevents warnings and doesn't seem to affect behavior.
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pub fn (db DB) exec_param_many(query string, params []string) []Row {
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unsafe {
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mut param_vals := &byteptr(malloc(params.len * 8))
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for i in 0..params.len {
param_vals[i] = params[i].str
}
res := C.PQexecParams(db.conn, query.str, params.len, 0, param_vals, 0, 0, 0)
free(param_vals)
return db.handle_error_or_result(res, 'exec_param_many')
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}
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}
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pub fn (db DB) exec_param2(query string, param, param2 string) []Row {
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mut param_vals := [2]byteptr
param_vals[0] = param.str
param_vals[1] = param2.str
res := C.PQexecParams(db.conn, query.str, 2, 0, param_vals, 0, 0, 0)
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return db.handle_error_or_result(res, 'exec_param2')
}
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pub fn (db DB) exec_param(query string, param string) []Row {
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mut param_vals := [1]byteptr
param_vals[0] = param.str
res := C.PQexecParams(db.conn, query.str, 1, 0, param_vals, 0, 0, 0)
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return db.handle_error_or_result(res, 'exec_param')
}
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fn (db DB) handle_error_or_result(res voidptr, elabel string) []Row {
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e := string(C.PQerrorMessage(db.conn))
if e != '' {
println('pg $elabel error:')
println(e)
return res_to_rows(res)
}
return res_to_rows(res)
}