Add the SQLITE_CHANGESETAPPLY_FKNOACTION flag to sqlite3session.h, for passing to sqlite3changeset_apply_v2() to cause all foreign key constraints to behave as if they were declared NO ACTION.

FossilOrigin-Name: fc9f82ea084159eaf3dd1757b96d17d1201b00c4e06455a7dcd8067172b25f28

ext/session/sessionnoact.test

@@ -0,0 +1,88 @@
+# 2023 October 20
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.
+#
+
+if {![info exists testdir]} {
+  set testdir [file join [file dirname [info script]] .. .. test]
+} 
+source [file join [file dirname [info script]] session_common.tcl]
+source $testdir/tester.tcl
+ifcapable !session {finish_test; return}
+
+set testprefix sessionnoact
+
+do_execsql_test 1.0 {
+  CREATE TABLE p1(a INTEGER PRIMARY KEY, b, c UNIQUE);
+  INSERT INTO p1 VALUES(1, 1, 'one');
+  INSERT INTO p1 VALUES(2, 2, 'two');
+  INSERT INTO p1 VALUES(3, 3, 'three');
+  INSERT INTO p1 VALUES(4, 4, 'four');
+}
+
+db_save
+
+set C [changeset_from_sql {
+  DELETE FROM p1 WHERE a=2;
+  UPDATE p1 SET c='six' WHERE a=3;
+  INSERT INTO p1 VALUES(5, 5, 'two');
+  INSERT INTO p1 VALUES(6, 6, 'three');
+}]
+
+db_restore_and_reopen
+
+do_execsql_test 1.1 {
+  CREATE TABLE c1(x INTEGER PRIMARY KEY, y,
+    FOREIGN KEY(y) REFERENCES p1(c) ON DELETE CASCADE ON UPDATE SET NULL
+  );
+
+  INSERT INTO c1 VALUES(10, 'one');
+  INSERT INTO c1 VALUES(20, 'two');
+  INSERT INTO c1 VALUES(30, 'three');
+  INSERT INTO c1 VALUES(40, 'four');
+}
+
+db_save
+
+do_execsql_test 1.2 {
+  PRAGMA foreign_keys = 1;
+}
+
+set ::nConflict 0
+proc conflict {args} {
+  incr ::nConflict
+  return "OMIT"
+}
+
+sqlite3changeset_apply_v2 db $C conflict
+
+do_execsql_test 1.3 {
+  SELECT * FROM c1
+} {
+  10 one
+  30 {}
+  40 four
+}
+
+db_restore_and_reopen
+sqlite3changeset_apply_v2 -noaction db $C conflict
+
+do_execsql_test 1.4 {
+  SELECT * FROM c1
+} {
+  10 one
+  20 two
+  30 three
+  40 four
+}
+
+
+finish_test

ext/session/sqlite3session.c

@@ -5322,11 +5322,22 @@ int sqlite3changeset_apply_v2(
   sqlite3_changeset_iter *pIter;  /* Iterator to skip through changeset */  
   int bInv = !!(flags & SQLITE_CHANGESETAPPLY_INVERT);
   int rc = sessionChangesetStart(&pIter, 0, 0, nChangeset, pChangeset, bInv, 1);
+  u64 savedFlag = db->flags & SQLITE_FkNoAction;
+
+  if( flags & SQLITE_CHANGESETAPPLY_FKNOACTION ){
+    db->flags |= ((u64)SQLITE_FkNoAction);
+  }
+
   if( rc==SQLITE_OK ){
     rc = sessionChangesetApply(
         db, pIter, xFilter, xConflict, pCtx, ppRebase, pnRebase, flags
     );
   }
+
+  if( (flags & SQLITE_CHANGESETAPPLY_FKNOACTION) && savedFlag==0 ){
+    assert( db->flags & SQLITE_FkNoAction );
+    db->flags &= ((u64)SQLITE_FkNoAction);
+  }
   return rc;
 }
 

ext/session/sqlite3session.h

@@ -1318,10 +1318,17 @@ int sqlite3changeset_apply_v2(
 **    <li>an insert change if all fields of the conflicting row match
 **        the row being inserted.
 **    </ul>
+**
+** <dt>SQLITE_CHANGESETAPPLY_FKNOACTION <dd>
+**   If this flag it set, then all foreign key constraints in the target
+**   database behave as if they were declared with "ON UPDATE NO ACTION ON
+**   DELETE NO ACTION", even if they are actually CASCADE, RESTRICT, SET NULL
+**   or SET DEFAULT.
 */
 #define SQLITE_CHANGESETAPPLY_NOSAVEPOINT   0x0001
 #define SQLITE_CHANGESETAPPLY_INVERT        0x0002
 #define SQLITE_CHANGESETAPPLY_IGNORENOOP    0x0004
+#define SQLITE_CHANGESETAPPLY_FKNOACTION    0x0008
 
 /* 
 ** CAPI3REF: Constants Passed To The Conflict Handler

ext/session/test_session.c

@@ -812,9 +812,12 @@ static int SQLITE_TCLAPI testSqlite3changesetApply(
     while( objc>1 ){
       const char *z1 = Tcl_GetString(objv[1]);
       int n = strlen(z1);
-      if( n>1 && n<=12 && 0==sqlite3_strnicmp("-nosavepoint", z1, n) ){
+      if( n>3 && n<=12 && 0==sqlite3_strnicmp("-nosavepoint", z1, n) ){
         flags |= SQLITE_CHANGESETAPPLY_NOSAVEPOINT;
       }
+      else if( n>3 && n<=9 && 0==sqlite3_strnicmp("-noaction", z1, n) ){
+        flags |= SQLITE_CHANGESETAPPLY_FKNOACTION;
+      }
       else if( n>2 && n<=7 && 0==sqlite3_strnicmp("-invert", z1, n) ){
         flags |= SQLITE_CHANGESETAPPLY_INVERT;
       }