case consistency part 8 - Nim - This repository contains the Nim compiler, Nim's stdlib, tools, and documentation. (mirror)

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author	Araq <rumpf_a@web.de>	2013-12-28 01:47:40 +0100
committer	Araq <rumpf_a@web.de>	2013-12-28 01:47:40 +0100
commit	e2648fa3fb7b00b3485b8f34daf7dcdb32d53778 (patch)
tree	5f96bb75ce474d66ac547df16bc0ac2f2f39d23b /tinyc/lib
parent	7e0da3e8f7687ba9eb2c24beca7b7a833621d1bc (diff)
download	Nim-e2648fa3fb7b00b3485b8f34daf7dcdb32d53778.tar.gz

case consistency part 8

Diffstat (limited to 'tinyc/lib')

0 files changed, 0 insertions, 0 deletions

# # # Nim's Runtime Library # (c) Copyright 2015 Andreas Rumpf # # See the file "copying.txt", included in this # distribution, for details about the copyright. # ## A higher level `PostgreSQL`:idx: database wrapper. This interface ## is implemented for other databases also. ## ## See also: `db_odbc <db_odbc.html>`_, `db_sqlite <db_sqlite.html>`_, ## `db_mysql <db_mysql.html>`_. ## ## Parameter substitution ## ---------------------- ## ## All ``db_*`` modules support the same form of parameter substitution. ## That is, using the ``?`` (question mark) to signify the place where a ## value should be placed. For example: ## ## .. code-block:: Nim ## sql"INSERT INTO myTable (colA, colB, colC) VALUES (?, ?, ?)" ## ## **Note**: There are two approaches to parameter substitution support by ## this module. ## ## 1. ``SqlQuery`` using ``?, ?, ?, ...`` (same as all the ``db_*`` modules) ## ## 2. ``SqlPrepared`` using ``$1, $2, $3, ...`` ## ## .. code-block:: Nim ## prepare(db, "myExampleInsert", ## sql"""INSERT INTO myTable ## (colA, colB, colC) ## VALUES ($1, $2, $3)""", ## 3) ## ## Examples ## -------- ## ## Opening a connection to a database ## ================================== ## ## .. code-block:: Nim ## import db_postgres ## let db = open("localhost", "user", "password", "dbname") ## db.close() ## ## Creating a table ## ================ ## ## .. code-block:: Nim ## db.exec(sql"DROP TABLE IF EXISTS myTable") ## db.exec(sql("""CREATE TABLE myTable ( ## id integer, ## name varchar(50) not null)""")) ## ## Inserting data ## ============== ## ## .. code-block:: Nim ## db.exec(sql"INSERT INTO myTable (id, name) VALUES (0, ?)", ## "Dominik") import strutils, postgres import db_common export db_common type DbConn* = PPGconn ## encapsulates a database connection Row* = seq[string] ## a row of a dataset. NULL database values will be ## converted to nil. InstantRow* = tuple[res: PPGresult, line: int32] ## a handle that can be ## used to get a row's ## column text on demand SqlPrepared* = distinct string ## a identifier for the prepared queries {.deprecated: [TRow: Row, TDbConn: DbConn, TSqlPrepared: SqlPrepared].} proc dbError*(db: DbConn) {.noreturn.} = ## raises a DbError exception. var e: ref DbError new(e) e.msg = $pqErrorMessage(db) raise e proc dbQuote*(s: string): string = ## DB quotes the string. result = "'" for c in items(s): if c == '\'': add(result, "''") else: add(result, c) add(result, '\'') proc dbFormat(formatstr: SqlQuery, args: varargs[string]): string = result = "" var a = 0 if args.len > 0 and not string(formatstr).contains("?"): dbError("""parameter substitution expects "?" """) for c in items(string(formatstr)): if c == '?': if args[a] == nil: add(result, "NULL") else: add(result, dbQuote(args[a])) inc(a) else: add(result, c) proc tryExec*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]): bool {.tags: [ReadDbEffect, WriteDbEffect].} = ## tries to execute the query and returns true if successful, false otherwise. var res = pqexecParams(db, dbFormat(query, args), 0, nil, nil, nil, nil, 0) result = pqresultStatus(res) == PGRES_COMMAND_OK pqclear(res) proc tryExec*(db: DbConn, stmtName: SqlPrepared, args: varargs[string, `$`]): bool {.tags: [ ReadDbEffect, WriteDbEffect].} = ## tries to execute the query and returns true if successful, false otherwise. var arr = allocCStringArray(args) var res = pqexecPrepared(db, stmtName.string, int32(args.len), arr, nil, nil, 0) deallocCStringArray(arr) result = pqresultStatus(res) == PGRES_COMMAND_OK pqclear(res) proc exec*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]) {. tags: [ReadDbEffect, WriteDbEffect].} = ## executes the query and raises EDB if not successful. var res = pqexecParams(db, dbFormat(query, args), 0, nil, nil, nil, nil, 0) if pqresultStatus(res) != PGRES_COMMAND_OK: dbError(db) pqclear(res) proc exec*(db: DbConn, stmtName: SqlPrepared, args: varargs[string]) {.tags: [ReadDbEffect, WriteDbEffect].} = 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): Row = newSeq(result, L) for i in 0..L-1: result[i] = "" proc setupQuery(db: DbConn, query: SqlQuery, args: varargs[string]): PPGresult = result = pqexec(db, dbFormat(query, args)) if pqResultStatus(result) != PGRES_TUPLES_OK: dbError(db) proc setupQuery(db: DbConn, stmtName: SqlPrepared, 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: DbConn; stmtName: string, query: SqlQuery; nParams: int): SqlPrepared = ## Creates a new ``SqlPrepared`` statement. Parameter substitution is done ## via ``$1``, ``$2``, ``$3``, etc. if nParams > 0 and not string(query).contains("$1"): dbError("parameter substitution expects \"$1\"") var res = pqprepare(db, stmtName, query.string, int32(nParams), nil) if pqResultStatus(res) != PGRES_COMMAND_OK: dbError(db) return SqlPrepared(stmtName) proc setRow(res: PPGresult, r: var Row, line, cols: int32) = for col in 0..cols-1: setLen(r[col], 0) let x = pqgetvalue(res, line, col) if x.isNil: r[col] = nil else: add(r[col], x) iterator fastRows*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]): Row {.tags: [ReadDbEffect].} = ## 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 Postgres it is safe though. var res = setupQuery(db, query, 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) iterator fastRows*(db: DbConn, stmtName: SqlPrepared, args: varargs[string, `$`]): Row {.tags: [ReadDbEffect].} = ## executes the prepared query and iterates over the result dataset. var res = setupQuery(db, stmtName, args) var L = pqNfields(res) var result = newRow(L) for i in 0..pqNtuples(res)-1: setRow(res, result, i, L) yield result pqClear(res) iterator instantRows*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]): InstantRow {.tags: [ReadDbEffect].} = ## same as fastRows but returns a handle that can be used to get column text ## on demand using []. Returned handle is valid only within iterator body. var res = setupQuery(db, query, args) for i in 0..pqNtuples(res)-1: yield (res: res, line: i) pqClear(res) iterator instantRows*(db: DbConn, stmtName: SqlPrepared, args: varargs[string, `$`]): InstantRow {.tags: [ReadDbEffect].} = ## same as fastRows but returns a handle that can be used to get column text ## on demand using []. Returned handle is valid only within iterator body. var res = setupQuery(db, stmtName, args) for i in 0..pqNtuples(res)-1: yield (res: res, line: i) pqClear(res) proc `[]`*(row: InstantRow, col: int32): string {.inline.} = ## returns text for given column of the row $pqgetvalue(row.res, row.line, col) proc len*(row: InstantRow): int32 {.inline.} = ## returns number of columns in the row pqNfields(row.res) proc getRow*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]): Row {.tags: [ReadDbEffect].} = ## retrieves a single row. If the query doesn't return any rows, this proc ## will return a Row with empty strings for each column. var res = setupQuery(db, query, args) var L = pqnfields(res) result = newRow(L) setRow(res, result, 0, L) pqclear(res) proc getRow*(db: DbConn, stmtName: SqlPrepared, args: varargs[string, `$`]): Row {.tags: [ReadDbEffect].} = var res = setupQuery(db, stmtName, args) var L = pqNfields(res) result = newRow(L) setRow(res, result, 0, L) pqClear(res) proc getAllRows*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]): seq[Row] {. tags: [ReadDbEffect].} = ## executes the query and returns the whole result dataset. result = @[] for r in fastRows(db, query, args): result.add(r) proc getAllRows*(db: DbConn, stmtName: SqlPrepared, args: varargs[string, `$`]): seq[Row] {.tags: [ReadDbEffect].} = ## executes the prepared query and returns the whole result dataset. result = @[] for r in fastRows(db, stmtName, args): result.add(r) iterator rows*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]): Row {.tags: [ReadDbEffect].} = ## same as `fastRows`, but slower and safe. for r in items(getAllRows(db, query, args)): yield r iterator rows*(db: DbConn, stmtName: SqlPrepared, args: varargs[string, `$`]): Row {.tags: [ReadDbEffect].} = ## same as `fastRows`, but slower and safe. for r in items(getAllRows(db, stmtName, args)): yield r proc getValue*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]): string {. tags: [ReadDbEffect].} = ## 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. var x = pqgetvalue(setupQuery(db, query, args), 0, 0) result = if isNil(x): "" else: $x proc getValue*(db: DbConn, stmtName: SqlPrepared, args: varargs[string, `$`]): string {. tags: [ReadDbEffect].} = ## 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. var x = pqgetvalue(setupQuery(db, stmtName, args), 0, 0) result = if isNil(x): "" else: $x proc tryInsertID*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]): int64 {. tags: [WriteDbEffect].}= ## executes the query (typically "INSERT") and returns the ## 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 ## named ``id``. var x = pqgetvalue(setupQuery(db, SqlQuery(string(query) & " RETURNING id"), args), 0, 0) if not isNil(x): result = parseBiggestInt($x) else: result = -1 proc insertID*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]): int64 {. tags: [WriteDbEffect].} = ## executes the query (typically "INSERT") and returns the ## generated ID for the row. For Postgre this adds ## ``RETURNING id`` to the query, so it only works if your primary key is ## named ``id``. result = tryInsertID(db, query, args) if result < 0: dbError(db) proc execAffectedRows*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]): int64 {.tags: [ ReadDbEffect, WriteDbEffect].} = ## executes the query (typically "UPDATE") and returns the ## number of affected rows. var q = dbFormat(query, args) var res = pqExec(db, q) if pqresultStatus(res) != PGRES_COMMAND_OK: dbError(db) result = parseBiggestInt($pqcmdTuples(res)) pqclear(res) proc execAffectedRows*(db: DbConn, stmtName: SqlPrepared, args: varargs[string, `$`]): int64 {.tags: [ ReadDbEffect, WriteDbEffect].} = ## executes the query (typically "UPDATE") and returns the ## number of affected rows. var arr = allocCStringArray(args) var res = pqexecPrepared(db, stmtName.string, int32(args.len), arr, nil, nil, 0) deallocCStringArray(arr) if pqresultStatus(res) != PGRES_COMMAND_OK: dbError(db) result = parseBiggestInt($pqcmdTuples(res)) pqclear(res) proc close*(db: DbConn) {.tags: [DbEffect].} = ## closes the database connection. if db != nil: pqfinish(db) proc open*(connection, user, password, database: string): DbConn {. tags: [DbEffect].} = ## opens a database connection. Raises `EDb` if the connection could not ## be established. ## ## Clients can also use Postgres keyword/value connection strings to ## connect. ## ## Example: ## ## .. code-block:: nim ## ## con = open("", "", "", "host=localhost port=5432 dbname=mydb") ## ## See http://www.postgresql.org/docs/current/static/libpq-connect.html#LIBPQ-CONNSTRING ## for more information. ## ## Note that the connection parameter is not used but exists to maintain ## the nim db api. result = pqsetdbLogin(nil, nil, nil, nil, database, user, password) if pqStatus(result) != CONNECTION_OK: dbError(result) # result = nil proc setEncoding*(connection: DbConn, encoding: string): bool {. tags: [DbEffect].} = ## sets the encoding of a database connection, returns true for ## success, false for failure. return pqsetClientEncoding(connection, encoding) == 0 # Tests are in ../../tests/untestable/tpostgres.


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