Handle BLOB column type in SQLite as binary data (#15681)

* Fixed not handling blob correctly in sqlite
* Fixed setLen commented by mistake
* Added binary example as db_sqlite doc
* Added tests for sqlite binary data

lib/impure/db_sqlite.nim

@@ -94,6 +94,57 @@
 ##
 ##    db.close()
 ##
+## Storing binary data example
+##----------------------------
+##
+## .. code-block:: nim
+##
+##   import random
+##
+##   ## Generate random float datas
+##   var orig = newSeq[float64](150)
+##   randomize()
+##   for x in orig.mitems:
+##     x = rand(1.0)/10.0
+##
+##   let db = open("mysqlite.db", "", "", "")
+##   block: ## Create database
+##     ## Binary datas needs to be of type BLOB in SQLite
+##     let createTableStr = sql"""CREATE TABLE test(
+##       id INTEGER NOT NULL PRIMARY KEY,
+##       data BLOB
+##     )
+##     """
+##     db.exec(createTableStr)
+##
+##   block: ## Insert data
+##     var id = 1
+##     ## Data needs to be converted to seq[byte] to be interpreted as binary by bindParams
+##     var dbuf = newSeq[byte](orig.len*sizeof(float64))
+##     copyMem(unsafeAddr(dbuf[0]), unsafeAddr(orig[0]), dbuf.len)
+##
+##     ## Use prepared statement to insert binary data into database
+##     var insertStmt = db.prepare("INSERT INTO test (id, data) VALUES (?, ?)")
+##     insertStmt.bindParams(id, dbuf)
+##     let bres = db.tryExec(insertStmt)
+##     ## Check insert
+##     doAssert(bres)
+##     # Destroy statement
+##     finalize(insertStmt)
+##
+##   block: ## Use getValue to select data
+##     var dataTest = db.getValue(sql"SELECT data FROM test WHERE id = ?", 1)
+##     ## Calculate sequence size from buffer size
+##     let seqSize = int(dataTest.len*sizeof(byte)/sizeof(float64))
+##     ## Copy binary string data in dataTest into a seq
+##     var res: seq[float64] = newSeq[float64](seqSize)
+##     copyMem(unsafeAddr(res[0]), addr(dataTest[0]), dataTest.len)
+##
+##     ## Check datas obtained is identical
+##     doAssert res == orig
+##
+##   db.close()
+##
 ##
 ## Note
 ## ====
@@ -242,10 +293,14 @@ proc setupQuery(db: DbConn, stmtName: SqlPrepared): SqlPrepared {.since: (1, 3).
 
 proc setRow(stmt: PStmt, r: var Row, cols: cint) =
   for col in 0'i32..cols-1:
-    setLen(r[col], column_bytes(stmt, col)) # set capacity
+    let cb = column_bytes(stmt, col)
-    setLen(r[col], 0)
+    setLen(r[col], cb) # set capacity
-    let x = column_text(stmt, col)
+    if column_type(stmt, col) == SQLITE_BLOB:
-    if not isNil(x): add(r[col], x)
+      copyMem(addr(r[col][0]), column_blob(stmt, col), cb)
+    else:
+      setLen(r[col], 0)
+      let x = column_text(stmt, col)
+      if not isNil(x): add(r[col], x)
 
 iterator fastRows*(db: DbConn, query: SqlQuery,
                    args: varargs[string, `$`]): Row {.tags: [ReadDbEffect].} =
@@ -558,8 +613,12 @@ proc getValue*(db: DbConn, query: SqlQuery,
     if cb == 0:
       result = ""
     else:
-      result = newStringOfCap(cb)
+      if column_type(stmt, 0) == SQLITE_BLOB:
-      add(result, column_text(stmt, 0))
+        result.setLen(cb)
+        copyMem(addr(result[0]), column_blob(stmt, 0), cb)
+      else:
+        result = newStringOfCap(cb)
+        add(result, column_text(stmt, 0))
   else:
     result = ""
   if finalize(stmt) != SQLITE_OK: dbError(db)
@@ -572,8 +631,12 @@ proc getValue*(db: DbConn,  stmtName: SqlPrepared): string
     if cb == 0:
       result = ""
     else:
-      result = newStringOfCap(cb)
+      if column_type(stmt, 0) == SQLITE_BLOB:
-      add(result, column_text(stmt, 0))
+        result.setLen(cb)
+        copyMem(addr(result[0]), column_blob(stmt, 0), cb)
+      else:
+        result = newStringOfCap(cb)
+        add(result, column_text(stmt, 0))
   else:
     result = ""
 

tests/stdlib/tsqlitebindatas.nim

@@ -0,0 +1,50 @@
+discard """
+  action: "run"
+  exitcode: 0
+"""
+import db_sqlite
+import random
+import os
+from stdtest/specialpaths import buildDir
+
+block tsqlitebindatas: ## db_sqlite binary data
+  const dbName = buildDir / "tsqlitebindatas.db"
+
+  let origName = "Bobby"
+  var orig = newSeq[float64](150)
+  randomize()
+  for x in orig.mitems:
+    x = rand(1.0)/10.0
+
+  discard tryRemoveFile(dbName)
+  let db = open(dbName, "", "", "")
+  let createTableStr = sql"""CREATE TABLE test(
+    id INTEGER NOT NULL PRIMARY KEY,
+    name TEXT,
+    data BLOB
+  )
+  """
+  db.exec(createTableStr)
+
+  var dbuf = newSeq[byte](orig.len*sizeof(float64))
+  copyMem(unsafeAddr(dbuf[0]), unsafeAddr(orig[0]), dbuf.len)
+
+  var insertStmt = db.prepare("INSERT INTO test (id, name, data) VALUES (?, ?, ?)")
+  insertStmt.bindParams(1, origName, dbuf)
+  let bres = db.tryExec(insertStmt)
+  doAssert(bres)
+
+  finalize(insertStmt)
+
+  var nameTest = db.getValue(sql"SELECT name FROM test WHERE id = ?", 1)
+  doAssert nameTest == origName
+
+  var dataTest = db.getValue(sql"SELECT data FROM test WHERE id = ?", 1)
+  let seqSize = int(dataTest.len*sizeof(byte)/sizeof(float64))
+  var res: seq[float64] = newSeq[float64](seqSize)
+  copyMem(unsafeAddr(res[0]), addr(dataTest[0]), dataTest.len)
+  doAssert res.len == orig.len
+  doAssert res == orig
+
+  db.close()
+  doAssert tryRemoveFile(dbName)