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#
#
# Nimrod's Runtime Library
# (c) Copyright 2012 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. NULL database values will be
## transformed always to the empty string.
EDb* = object of EIO ## exception that is raised if a database error occurs
TSqlQuery* = distinct string ## an SQL query string
FDb* = object of FIO ## effect that denotes a database operation
FReadDb* = object of FDb ## effect that denotes a read operation
FWriteDb* = object of FDb ## effect that denotes a write operation
proc sql*(query: string): TSqlQuery {.noSideEffect, inline.} =
## constructs a TSqlQuery from the string `query`. This is supposed to be
## used as a raw-string-literal modifier:
## ``sql"update user set counter = counter + 1"``
##
## If assertions are turned off, it does nothing. If assertions are turned
## on, later versions will check the string for valid syntax.
result = TSqlQuery(query)
proc dbError(db: TDbConn) {.noreturn.} =
## raises an EDb exception.
var e: ref EDb
new(e)
e.msg = $mysql.error(db)
raise e
proc dbError*(msg: string) {.noreturn.} =
## raises an EDb exception with message `msg`.
var e: ref EDb
new(e)
e.msg = msg
raise e
when false:
proc dbQueryOpt*(db: TDbConn, query: string, args: varargs[string, `$`]) =
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: varargs[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: varargs[string, `$`]): bool {.
tags: [FReadDB, FWriteDb].} =
## tries to execute the query and returns true if successful, false otherwise.
var q = dbFormat(query, args)
return mysql.RealQuery(db, q, q.len) == 0'i32
proc rawExec(db: TDbConn, query: TSqlQuery, args: varargs[string, `$`]) =
var q = dbFormat(query, args)
if mysql.RealQuery(db, q, q.len) != 0'i32: dbError(db)
proc exec*(db: TDbConn, query: TSqlQuery, args: varargs[string, `$`]) {.
tags: [FReadDB, FWriteDb].} =
## executes the query and raises EDB if not successful.
var q = dbFormat(query, args)
if mysql.RealQuery(db, q, q.len) != 0'i32: dbError(db)
proc newRow(L: int): TRow =
newSeq(result, L)
for i in 0..L-1: result[i] = ""
proc properFreeResult(sqlres: mysql.PRES, row: cstringArray) =
if row != nil:
while mysql.FetchRow(sqlres) != nil: discard
mysql.FreeResult(sqlres)
iterator fastRows*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): TRow {.tags: [FReadDB].} =
## 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!.
rawExec(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 getRow*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): TRow {.tags: [FReadDB].} =
## retrieves a single row. If the query doesn't return any rows, this proc
## will return a TRow with empty strings for each column.
rawExec(db, query, args)
var sqlres = mysql.UseResult(db)
if sqlres != nil:
var L = int(mysql.NumFields(sqlres))
result = newRow(L)
var row = mysql.FetchRow(sqlres)
if row != nil:
for i in 0..L-1:
setLen(result[i], 0)
add(result[i], row[i])
properFreeResult(sqlres, row)
proc getAllRows*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): seq[TRow] {.tags: [FReadDB].} =
## executes the query and returns the whole result dataset.
result = @[]
rawExec(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] = $row[i]
inc(j)
mysql.FreeResult(sqlres)
iterator rows*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): TRow {.tags: [FReadDB].} =
## same as `FastRows`, but slower and safe.
for r in items(GetAllRows(db, query, args)): yield r
proc getValue*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): string {.tags: [FReadDB].} =
## executes the query and returns the first column of the first row of the
## result dataset. Returns "" if the dataset contains no rows or the database
## value is NULL.
result = ""
for row in FastRows(db, query, args):
result = row[0]
break
proc tryInsertId*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): int64 {.tags: [FWriteDb].} =
## 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: varargs[string, `$`]): int64 {.tags: [FWriteDb].} =
## executes the query (typically "INSERT") and returns the
## generated ID for the row.
result = TryInsertID(db, query, args)
if result < 0: dbError(db)
proc execAffectedRows*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): int64 {.
tags: [FReadDB, FWriteDb].} =
## runs the query (typically "UPDATE") and returns the
## number of affected rows
rawExec(db, query, args)
result = mysql.AffectedRows(db)
proc close*(db: TDbConn) {.tags: [FDb].} =
## closes the database connection.
if db != nil: mysql.close(db)
proc open*(connection, user, password, database: string): TDbConn {.
tags: [FDb].} =
## 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")
let
colonPos = connection.find(':')
host = if colonPos < 0: connection
else: substr(connection, 0, colonPos-1)
port: int32 = if colonPos < 0: 0'i32
else: substr(connection, colonPos+1).parseInt.int32
if mysql.RealConnect(result, host, user, password, database,
port, nil, 0) == nil:
var errmsg = $mysql.error(result)
db_mysql.Close(result)
dbError(errmsg)
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