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#
#
# Nimrod's Runtime Library
# (c) Copyright 2010 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## A higher level `mySQL`:idx: database wrapper. The same interface is
## implemented for other databases too.
import strutils, mysql
type
TDbConn* = PMySQL ## encapsulates a database connection
TRow* = seq[string] ## a row of a dataset
EDb* = object of EIO ## exception that is raised if a database error occurs
TSqlQuery* = distinct string ## an SQL query string
proc dbError(db: TDbConn) {.noreturn.} =
## raises an EDb exception.
var e: ref EDb
new(e)
e.msg = $mysql.error(db)
raise e
proc dbError*(msg: string) {.noreturn.} =
## raises an EDb exception with message `msg`.
var e: ref EDb
new(e)
e.msg = msg
raise e
when false:
proc dbQueryOpt*(db: TDbConn, query: string, args: openarray[string]) =
var stmt = mysql_stmt_init(db)
if stmt == nil: dbError(db)
if mysql_stmt_prepare(stmt, query, len(query)) != 0:
dbError(db)
var
binding: seq[MYSQL_BIND]
discard mysql_stmt_close(stmt)
proc dbQuote(s: string): string =
result = "'"
for c in items(s):
if c == '\'': add(result, "''")
else: add(result, c)
add(result, '\'')
proc dbFormat(formatstr: TSqlQuery, args: openarray[string]): string =
result = ""
var a = 0
for c in items(string(formatstr)):
if c == '?':
add(result, dbQuote(args[a]))
inc(a)
else:
add(result, c)
proc TryExec*(db: TDbConn, query: TSqlQuery, args: openarray[string]): bool =
## tries to execute the query and returns true if successful, false otherwise.
var q = dbFormat(query, args)
return mysql.RealQuery(db, q, q.len) == 0'i32
proc Exec*(db: TDbConn, query: TSqlQuery, args: openarray[string]) =
## executes the query and raises EDB if not successful.
var q = dbFormat(query, args)
if mysql.RealQuery(db, q, q.len) != 0'i32: dbError(db)
proc newRow(L: int): TRow =
newSeq(result, L)
for i in 0..L-1: result[i] = ""
proc properFreeResult(sqlres: mysql.PRES, row: cstringArray) =
if row != nil:
while mysql.FetchRow(sqlres) != nil: nil
mysql.FreeResult(sqlres)
iterator FastRows*(db: TDbConn, query: TSqlQuery,
args: openarray[string]): TRow =
## executes the query and iterates over the result dataset. This is very
## fast, but potenially dangerous: If the for-loop-body executes another
## query, the results can be undefined. For MySQL this is the case!.
Exec(db, query, args)
var sqlres = mysql.UseResult(db)
if sqlres != nil:
var L = int(mysql.NumFields(sqlres))
var result = newRow(L)
var row: cstringArray
while true:
row = mysql.FetchRow(sqlres)
if row == nil: break
for i in 0..L-1:
setLen(result[i], 0)
add(result[i], row[i])
yield result
properFreeResult(sqlres, row)
proc GetAllRows*(db: TDbConn, query: TSqlQuery,
args: openarray[string]): seq[TRow] =
## executes the query and returns the whole result dataset.
result = @[]
Exec(db, query, args)
var sqlres = mysql.UseResult(db)
if sqlres != nil:
var L = int(mysql.NumFields(sqlres))
var row: cstringArray
var j = 0
while true:
row = mysql.FetchRow(sqlres)
if row == nil: break
setLen(result, j+1)
newSeq(result[j], L)
for i in 0..L-1: result[j][i] = $row[i]
inc(j)
mysql.FreeResult(sqlres)
iterator Rows*(db: TDbConn, query: TSqlQuery,
args: openarray[string]): TRow =
## same as `FastRows`, but slower and safe.
for r in items(GetAllRows(db, query, args)): yield r
proc GetValue*(db: TDbConn, query: TSqlQuery,
args: openarray[string]): string =
## executes the query and returns the result dataset's the first column
## of the first row. Returns "" if the dataset contains no rows. This uses
## `FastRows`, so it inherits its fragile behaviour.
result = ""
for row in FastRows(db, query, args):
result = row[0]
break
proc TryInsertID*(db: TDbConn, query: TSqlQuery,
args: openarray[string]): int64 =
## executes the query (typically "INSERT") and returns the
## generated ID for the row or -1 in case of an error.
var q = dbFormat(query, args)
if mysql.RealQuery(db, q, q.len) != 0'i32:
result = -1'i64
else:
result = mysql.InsertId(db)
proc InsertID*(db: TDbConn, query: TSqlQuery, args: openArray[string]): int64 =
## executes the query (typically "INSERT") and returns the
## generated ID for the row.
result = TryInsertID(db, query, args)
if result < 0: dbError(db)
proc ExecAffectedRows*(db: TDbConn, query: TSqlQuery,
args: openArray[string]): int64 =
## runs the query (typically "UPDATE") and returns the
## number of affected rows
Exec(db, query, args)
result = mysql.AffectedRows(db)
proc Close*(db: TDbConn) =
## closes the database connection.
if db != nil: mysql.Close(db)
proc Open*(connection, user, password, database: string): TDbConn =
## opens a database connection. Raises `EDb` if the connection could not
## be established.
result = mysql.Init(nil)
if result == nil: dbError("could not open database connection")
if mysql.RealConnect(result, "", user, password, database,
0'i32, nil, 0) == nil:
var errmsg = $mysql.error(result)
db_mysql.Close(result)
dbError(errmsg)
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