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Add postgresql prepared queries and stop relying on string formatting

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for sql parameter passing
This commit is contained in:
Erwan Ameil 2014-08-29 11:29:19 +02:00
commit 08f1c6100b
2 changed files with 86 additions and 28 deletions
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112
lib/impure/db_postgres.nim
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@ -19,12 +19,13 @@ type
EDb* = object of EIO ## exception that is raised if a database error occurs EDb* = object of EIO ## exception that is raised if a database error occurs
TSqlQuery* = distinct string ## an SQL query string TSqlQuery* = distinct string ## an SQL query string
TSqlPrepared* = distinct string ## a identifier for the prepared queries
FDb* = object of FIO ## effect that denotes a database operation FDb* = object of FIO ## effect that denotes a database operation
FReadDb* = object of FDB ## effect that denotes a read operation FReadDb* = object of FDB ## effect that denotes a read operation
FWriteDb* = object of FDB ## effect that denotes a write operation FWriteDb* = object of FDB ## effect that denotes a write operation
proc sql*(query: string): TSqlQuery {.noSideEffect, inline.} = proc sql*(query: string): TSqlQuery {.noSideEffect, inline.} =
## constructs a TSqlQuery from the string `query`. This is supposed to be ## constructs a TSqlQuery from the string `query`. This is supposed to be
## used as a raw-string-literal modifier: ## used as a raw-string-literal modifier:
## ``sql"update user set counter = counter + 1"`` ## ``sql"update user set counter = counter + 1"``
@ -33,14 +34,14 @@ proc sql*(query: string): TSqlQuery {.noSideEffect, inline.} =
## on, later versions will check the string for valid syntax. ## on, later versions will check the string for valid syntax.
result = TSqlQuery(query) result = TSqlQuery(query)
proc dbError(db: TDbConn) {.noreturn.} = proc dbError*(db: TDbConn) {.noreturn.} =
## raises an EDb exception. ## raises an EDb exception.
var e: ref EDb var e: ref EDb
new(e) new(e)
e.msg = $PQerrorMessage(db) e.msg = $PQerrorMessage(db)
raise e raise e
proc dbError*(msg: string) {.noreturn.} = proc dbError*(msg: string) {.noreturn.} =
## raises an EDb exception with message `msg`. ## raises an EDb exception with message `msg`.
var e: ref EDb var e: ref EDb
new(e) new(e)
@ -61,41 +62,70 @@ proc dbFormat(formatstr: TSqlQuery, args: varargs[string]): string =
if c == '?': if c == '?':
add(result, dbQuote(args[a])) add(result, dbQuote(args[a]))
inc(a) inc(a)
else: else:
add(result, c) add(result, c)
proc tryExec*(db: TDbConn, query: TSqlQuery, proc tryExec*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): bool {.tags: [FReadDB, FWriteDb].} = args: varargs[string, `$`]): bool {.tags: [FReadDB, FWriteDb].} =
## tries to execute the query and returns true if successful, false otherwise. ## tries to execute the query and returns true if successful, false otherwise.
var q = dbFormat(query, args) var arr = allocCStringArray(args)
var res = PQExec(db, q) var res = PQexecParams(db, query.string, int32(args.len), nil, arr,
nil, nil, 0)
deallocCStringArray(arr)
result = PQresultStatus(res) == PGRES_COMMAND_OK result = PQresultStatus(res) == PGRES_COMMAND_OK
PQclear(res) PQclear(res)
proc exec*(db: TDbConn, query: TSqlQuery, args: varargs[string, `$`]) {. proc exec*(db: TDbConn, query: TSqlQuery, args: varargs[string, `$`]) {.
tags: [FReadDB, FWriteDb].} = tags: [FReadDB, FWriteDb].} =
## executes the query and raises EDB if not successful. ## executes the query and raises EDB if not successful.
var q = dbFormat(query, args) var arr = allocCStringArray(args)
var res = PQExec(db, q) var res = PQexecParams(db, query.string, int32(args.len), nil, arr,
nil, nil, 0)
deallocCStringArray(arr)
if PQresultStatus(res) != PGRES_COMMAND_OK: dbError(db) if PQresultStatus(res) != PGRES_COMMAND_OK: dbError(db)
PQclear(res) PQclear(res)
proc exec*(db: TDbConn, stmtName: TSqlPrepared,
args: varargs[string]) {.tags: [FReadDB, FWriteDb].} =
var arr = allocCStringArray(args)
var res = PQexecPrepared(db, stmtName.string, int32(args.len), arr,
nil, nil, 0)
deallocCStringArray(arr)
if PQResultStatus(res) != PGRES_COMMAND_OK: dbError(db)
PQclear(res)
proc newRow(L: int): TRow = proc newRow(L: int): TRow =
newSeq(result, L) newSeq(result, L)
for i in 0..L-1: result[i] = "" for i in 0..L-1: result[i] = ""
proc setupQuery(db: TDbConn, query: TSqlQuery, proc setupQuery(db: TDbConn, query: TSqlQuery,
args: varargs[string]): PPGresult = args: varargs[string]): PPGresult =
var q = dbFormat(query, args) var arr = allocCStringArray(args)
result = PQExec(db, q) result = PQexecParams(db, query.string, int32(args.len), nil, arr,
if PQresultStatus(result) != PGRES_TUPLES_OK: dbError(db) nil, nil, 0)
deallocCStringArray(arr)
if PQResultStatus(result) != PGRES_TUPLES_OK: dbError(db)
proc setupQuery(db: TDbConn, stmtName: TSqlPrepared,
args: varargs[string]): PPGresult =
var arr = allocCStringArray(args)
result = PQexecPrepared(db, stmtName.string, int32(args.len), arr,
nil, nil, 0)
deallocCStringArray(arr)
if PQResultStatus(result) != PGRES_TUPLES_OK: dbError(db)
proc prepare*(db: TDbConn; stmtName: string, query: TSqlQuery;
nParams: int): TSqlPrepared =
var res = PQprepare(db, stmtName, query.string, int32(nParams), nil)
if PQResultStatus(res) != PGRES_COMMAND_OK: dbError(db)
return TSqlPrepared(stmtName)
proc setRow(res: PPGresult, r: var TRow, line, cols: int32) = proc setRow(res: PPGresult, r: var TRow, line, cols: int32) =
for col in 0..cols-1: for col in 0..cols-1:
setLen(r[col], 0) setLen(r[col], 0)
var x = PQgetvalue(res, line, col) var x = PQgetvalue(res, line, col)
add(r[col], x) add(r[col], x)
iterator fastRows*(db: TDbConn, query: TSqlQuery, iterator fastRows*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): TRow {.tags: [FReadDB].} = args: varargs[string, `$`]): TRow {.tags: [FReadDB].} =
## executes the query and iterates over the result dataset. This is very ## executes the query and iterates over the result dataset. This is very
@ -109,6 +139,17 @@ iterator fastRows*(db: TDbConn, query: TSqlQuery,
yield result yield result
PQclear(res) PQclear(res)
iterator fastRows*(db: TDbConn, stmtName: TSqlPrepared,
args: varargs[string, `$`]): TRow {.tags: [FReadDB].} =
## executes the prepared query and iterates over the result dataset.
var res = setupQuery(db, stmtName, args)
var L = PQnfields(res)
var result = newRow(L)
for i in 0..PQntuples(res)-1:
setRow(res, result, i, L)
yield result
PQclear(res)
proc getRow*(db: TDbConn, query: TSqlQuery, proc getRow*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): TRow {.tags: [FReadDB].} = args: varargs[string, `$`]): TRow {.tags: [FReadDB].} =
## retrieves a single row. If the query doesn't return any rows, this proc ## retrieves a single row. If the query doesn't return any rows, this proc
@ -119,40 +160,55 @@ proc getRow*(db: TDbConn, query: TSqlQuery,
setRow(res, result, 0, L) setRow(res, result, 0, L)
PQclear(res) PQclear(res)
proc getAllRows*(db: TDbConn, query: TSqlQuery, proc getRow*(db: TDbConn, stmtName: TSqlPrepared,
args: varargs[string, `$`]): TRow {.tags: [FReadDB].} =
var res = setupQuery(db, stmtName, args)
var L = PQnfields(res)
result = newRow(L)
setRow(res, result, 0, L)
PQclear(res)
proc getAllRows*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): seq[TRow] {.tags: [FReadDB].} = args: varargs[string, `$`]): seq[TRow] {.tags: [FReadDB].} =
## executes the query and returns the whole result dataset. ## executes the query and returns the whole result dataset.
result = @[] result = @[]
for r in FastRows(db, query, args): for r in FastRows(db, query, args):
result.add(r) result.add(r)
iterator rows*(db: TDbConn, query: TSqlQuery, proc getAllRows*(db: TDbConn, stmtName: TSqlPrepared,
args: varargs[string, `$`]): seq[TRow] {.tags: [FReadDB].} =
## executes the prepared query and returns the whole result dataset.
result = @[]
for r in FastRows(db, stmtName, args):
result.add(r)
iterator rows*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): TRow {.tags: [FReadDB].} = args: varargs[string, `$`]): TRow {.tags: [FReadDB].} =
## same as `FastRows`, but slower and safe. ## same as `FastRows`, but slower and safe.
for r in items(GetAllRows(db, query, args)): yield r for r in items(GetAllRows(db, query, args)): yield r
proc getValue*(db: TDbConn, query: TSqlQuery, proc getValue*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): string {.tags: [FReadDB].} = args: varargs[string, `$`]): string {.tags: [FReadDB].} =
## executes the query and returns the first column of the first row of the ## 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 ## result dataset. Returns "" if the dataset contains no rows or the database
## value is NULL. ## value is NULL.
var x = PQgetvalue(setupQuery(db, query, args), 0, 0) var x = PQgetvalue(setupQuery(db, query, args), 0, 0)
result = if isNil(x): "" else: $x result = if isNil(x): "" else: $x
proc tryInsertID*(db: TDbConn, query: TSqlQuery, proc tryInsertID*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): int64 {.tags: [FWriteDb].}= args: varargs[string, `$`]): int64 {.tags: [FWriteDb].}=
## executes the query (typically "INSERT") and returns the ## executes the query (typically "INSERT") and returns the
## generated ID for the row or -1 in case of an error. For Postgre this adds ## generated ID for the row or -1 in case of an error. For Postgre this adds
## ``RETURNING id`` to the query, so it only works if your primary key is ## ``RETURNING id`` to the query, so it only works if your primary key is
## named ``id``. ## named ``id``.
var x = PQgetvalue(setupQuery(db, TSqlQuery(string(query) & " RETURNING id"), var x = PQgetvalue(setupQuery(db, TSqlQuery(string(query) & " RETURNING id"),
args), 0, 0) args), 0, 0)
if not isNil(x): if not isNil(x):
result = ParseBiggestInt($x) result = ParseBiggestInt($x)
else: else:
result = -1 result = -1
proc insertID*(db: TDbConn, query: TSqlQuery, proc insertID*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): int64 {.tags: [FWriteDb].} = args: varargs[string, `$`]): int64 {.tags: [FWriteDb].} =
## executes the query (typically "INSERT") and returns the ## executes the query (typically "INSERT") and returns the
## generated ID for the row. For Postgre this adds ## generated ID for the row. For Postgre this adds
@ -161,9 +217,9 @@ proc insertID*(db: TDbConn, query: TSqlQuery,
result = TryInsertID(db, query, args) result = TryInsertID(db, query, args)
if result < 0: dbError(db) if result < 0: dbError(db)
proc execAffectedRows*(db: TDbConn, query: TSqlQuery, proc execAffectedRows*(db: TDbConn, query: TSqlQuery,
args: varargs[string, `$`]): int64 {.tags: [ args: varargs[string, `$`]): int64 {.tags: [
FReadDB, FWriteDb].} = FReadDB, FWriteDb].} =
## executes the query (typically "UPDATE") and returns the ## executes the query (typically "UPDATE") and returns the
## number of affected rows. ## number of affected rows.
var q = dbFormat(query, args) var q = dbFormat(query, args)
@ -172,7 +228,7 @@ proc execAffectedRows*(db: TDbConn, query: TSqlQuery,
result = parseBiggestInt($PQcmdTuples(res)) result = parseBiggestInt($PQcmdTuples(res))
PQclear(res) PQclear(res)
proc close*(db: TDbConn) {.tags: [FDb].} = proc close*(db: TDbConn) {.tags: [FDb].} =
## closes the database connection. ## closes the database connection.
if db != nil: PQfinish(db) if db != nil: PQfinish(db)

2
lib/wrappers/postgres.nim
View file

@ -213,6 +213,8 @@ proc PQexecParams*(conn: PPGconn, command: cstring, nParams: int32,
paramTypes: POid, paramValues: cstringArray, paramTypes: POid, paramValues: cstringArray,
paramLengths, paramFormats: ptr int32, resultFormat: int32): PPGresult{. paramLengths, paramFormats: ptr int32, resultFormat: int32): PPGresult{.
cdecl, dynlib: dllName, importc: "PQexecParams".} cdecl, dynlib: dllName, importc: "PQexecParams".}
proc PQprepare*(conn: PPGconn, stmtName, query: cstring, nParams: int32,
paramTypes: POid): PPGresult{.cdecl, dynlib: dllName, importc: "PQprepare".}
proc PQexecPrepared*(conn: PPGconn, stmtName: cstring, nParams: int32, proc PQexecPrepared*(conn: PPGconn, stmtName: cstring, nParams: int32,
paramValues: cstringArray, paramValues: cstringArray,
paramLengths, paramFormats: ptr int32, resultFormat: int32): PPGresult{. paramLengths, paramFormats: ptr int32, resultFormat: int32): PPGresult{.