sqlite3: support option type

.. and any integer when writing but don't support int32 on reads -
internally sqlite will truncate on overflow which isn't nice.

eth/db/kvstore_sqlite3.nim

@@ -93,10 +93,13 @@ proc bindParam(s: RawStmtPtr, n: int, val: auto): cint =
         sqlite3_bind_blob(s, n.cint, nil, 0.cint, nil)
     else:
       {.fatal: "Please add support for the '" & $typeof(val) & "' type".}
-  elif val is int32:
-    sqlite3_bind_int(s, n.cint, val)
-  elif val is int64:
-    sqlite3_bind_int64(s, n.cint, val)
+  elif val is SomeInteger:
+    sqlite3_bind_int64(s, n.cint, val.clong)
+  elif val is Option:
+    if val.isNone():
+      sqlite3_bind_null(s, n.cint)
+    else:
+      bindParam(s, n, val.get())
   else:
     {.fatal: "Please add support for the '" & $typeof(val) & "' type".}
 
@@ -125,13 +128,15 @@ proc exec*[P](s: SqliteStmt[P, void], params: P): KvResult[void] =
 
   res
 
-template readResult(s: RawStmtPtr, column: cint, T: type): auto =
-  when T is int32:
-    sqlite3_column_int(s, column)
-  elif T is int64:
+template readSimpleResult(s: RawStmtPtr, column: cint, T: type): auto =
+  when T is int64:
     sqlite3_column_int64(s, column)
-  elif T is int:
-    {.fatal: "Please use specify either int32 or int64 precisely".}
+  elif T is SomeInteger:
+    # sqlite integers are "up to" 8 bytes in size, so rather than silently
+    # truncate them, we support only 64-bit integers when reading and let the
+    # calling code deal with it - careful though, anything that is not an
+    # integer (ie TEXT) is returned as 0
+    {.fatal: "Use int64 for reading integers".}
   elif T is openArray[byte]:
     let
       p = cast[ptr UncheckedArray[byte]](sqlite3_column_blob(s, column))
@@ -161,6 +166,15 @@ template readResult(s: RawStmtPtr, column: cint, T: type): auto =
   else:
     {.fatal: "Please add support for the '" & $(T) & "' type".}
 
+template readResult(s: RawStmtPtr, column: cint, T: type): auto =
+  when T is Option:
+    if sqlite3_column_type(s, column) == SQLITE_NULL:
+      none(typeof(default(T).get()))
+    else:
+      some(readSimpleResult(s, column, typeof(default(T).get())))
+  else:
+    readSimpleResult(s, column, T)
+
 template readResult(s: RawStmtPtr, T: type): auto =
   when T is tuple:
     var res: T

tests/db/test_kvstore_sqlite3.nim

@@ -1,7 +1,7 @@
 {.used.}
 
 import
-  std/os,
+  std/[os, options],
   testutils/unittests,
   ../../eth/db/[kvstore, kvstore_sqlite3],
   ./test_kvstore
@@ -45,7 +45,6 @@ procSuite "SqStoreRef":
       NoParams, int64).get
 
     var totalRecords = 0
-    echo "About to call total records"
     let countRes = countStmt.exec do (res: int64):
       totalRecords = int res
 
@@ -138,7 +137,6 @@ procSuite "SqStoreRef":
       NoParams, int64).get
 
     var totalRecords = 0
-    echo "About to call total attestations"
     let countRes = countStmt.exec do (res: int64):
       totalRecords = int res
 
@@ -178,3 +176,43 @@ procSuite "SqStoreRef":
         source == 2
         target == 4
         digest == hash
+
+  test "null values":
+    #
+    let db = SqStoreRef.init("", "test", inMemory = true)[]
+    defer: db.close()
+
+    let createTableRes = db.exec """
+      CREATE TABLE IF NOT EXISTS testnull(
+         a INTEGER PRIMARY KEY,
+         b INTEGER NULL,
+         c INTEGER NULL
+      );
+    """
+    check createTableRes.isOk
+
+    type
+      ABC = (int64, Option[int64], Option[int64])
+    let insertStmt = db.prepareStmt("""
+      INSERT INTO testnull(a, b, c) VALUES (?,?,?);
+    """, ABC, void).get()
+
+    const val = (42'i64, none(int64), some(44'i64))
+    check:
+      insertStmt.exec(val).isOk()
+
+    let selectStmt = db.prepareStmt("""
+      SELECT a, b, c FROM testnull
+      """, NoParams, ABC).get()
+
+    block:
+      var abc: ABC
+      let selectRes = selectStmt.exec do (res: ABC):
+        abc = res
+
+      if selectRes.isErr:
+        echo selectRes.error
+
+      check:
+        selectRes.isOk and selectRes.get == true
+        abc == val