More postgres test code. Added getValue for PreparedStmts.

Ref #3569. Ref #3560.

lib/impure/db_postgres.nim

@@ -162,8 +162,10 @@ proc setupQuery(db: DbConn, stmtName: SqlPrepared,
 
 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" """)
+    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)
@@ -282,6 +284,15 @@ proc getValue*(db: DbConn, query: SqlQuery,
   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].}=

tests/untestable/tpostgres.nim

@@ -1,4 +1,5 @@
-import db_postgres
+import db_postgres, strutils
+
 
 let db = open("localhost", "dom", "", "test")
 db.exec(sql"DROP TABLE IF EXISTS myTable")
@@ -12,4 +13,70 @@ doAssert db.getValue(sql"SELECT name FROM myTable") == name
 # Check issue #3513
 doAssert db.getValue(sql"SELECT name FROM myTable") == name
 
+
+# issue #3560
+proc addToDb(conn: DbConn, fileId: int, fileName: string): int64 =
+  result = conn.insertId(sql("INSERT into files (id, filename) VALUES (?, ?)"), fileId, fileName)
+
+db.exec(sql"DROP TABLE IF EXISTS files")
+db.exec(sql"DROP TABLE IF EXISTS fileobjects")
+db.exec(sql("""CREATE TABLE FILEOBJECTS(
+               ID             SERIAL PRIMARY KEY,
+               FILE_SIZE      INT,
+               MD5            CHAR(32)  NOT NULL UNIQUE
+            );"""))
+
+db.exec(sql("""CREATE TABLE FILES(
+               ID                  SERIAL PRIMARY KEY,
+               OBJECT_ID           INT,
+               FILENAME            TEXT NOT NULL,
+               URI                 TEXT,
+               SCHEME              CHAR(10),
+               PUBLIC              BOOLEAN DEFAULT FALSE,
+               CONSTRAINT fk1_fileobjs FOREIGN KEY (object_id)
+               REFERENCES fileobjects (id) MATCH SIMPLE
+               ON DELETE CASCADE
+            );"""))
+
+let f1 = db.addToDb(1, "hello.tmp")
+doAssert f1 == 1
+let f2 = db.addToDb(2, "hello2.tmp")
+doAssert f2 == 2
+
+# PreparedStmt vs. normal query
+try:
+  echo db.getValue(sql("select * from files where id = $1"), 1)
+  doAssert false, "Exception expected"
+except DbError:
+  let msg = getCurrentExceptionMsg().normalize
+  doAssert "expects" in msg
+  doAssert "?" in msg
+  doAssert "parameter substitution" in msg
+
+doAssert db.getValue(sql("select filename from files where id = ?"), 1) == "hello.tmp"
+
+var first = prepare(db, "one", sql"select filename from files where id = $1", 1)
+doAssert db.getValue(first, 1) == "hello.tmp"
+
+try:
+  var second = prepare(db, "two", sql"select filename from files where id = ?", 1)
+  doAssert false, "Exception expected"
+except:
+  let msg = getCurrentExceptionMsg().normalize
+  doAssert "expects" in msg
+  doAssert "$1" in msg
+  doAssert "parameter substitution" in msg
+
+# issue #3569
+db.exec(SqlQuery("DROP TABLE IF EXISTS tags"))
+db.exec(SqlQuery("CREATE TABLE tags(id serial UNIQUE, name varchar(255))"))
+
+for i in 1..10:
+  var name = "t" & $i
+  echo(name)
+  discard db.getRow(
+    SqlQuery("INSERT INTO tags(name) VALUES(\'$1\') RETURNING id" % [name]))
+
+echo("All tests succeeded!")
+
 db.close()