fix the bug that modify account name will delete all transaction unde…

…r the account

app/src/main/java/org/gnucash/android/db/DatabaseAdapter.java

@@ -56,6 +56,10 @@ public abstract class DatabaseAdapter<Model extends BaseModel> {
 
     protected SQLiteStatement mReplaceStatement;
 
+    public enum UpdateMethod {
+        insert, update, replace
+    };
+
     /**
      * Opens the database adapter with an existing database
      * @param db SQLiteDatabase object
@@ -620,6 +624,20 @@ public void setTransactionSuccessful() {
         mDb.setTransactionSuccessful();
     }
 
+    /// Foreign key constraits should be enabled in general.
+    /// But if it affects speed (check constraints takes time)
+    /// and the constrained can be assured by the program,
+    /// or if some SQL exec will cause deletion of records
+    /// (like use replace in accounts update will delete all transactions)
+    /// that need not be deleted, then it can be disabled temporarily
+    public void enableForeignKey(boolean enable) {
+        if (enable){
+            mDb.execSQL("PRAGMA foreign_keys=ON");
+        } else {
+            mDb.execSQL("PRAGMA foreign_keys=OFF");
+        }
+    }
+
     /**
      * Expose mDb.endTransaction()
      */

app/src/main/java/org/gnucash/android/ui/account/AccountFormFragment.java

@@ -846,7 +846,9 @@ private void saveAccount() {
 		if (mAccountsDbAdapter == null)
 			mAccountsDbAdapter = AccountsDbAdapter.getInstance();
         // bulk update, will not update transactions
+        mAccountsDbAdapter.enableForeignKey(false);
 		mAccountsDbAdapter.bulkAddRecords(accountsToUpdate);
+        mAccountsDbAdapter.enableForeignKey(true);
 
 		finishFragment();
 	}