Clearing the app's data

[beppo-ivel]

Each time if I build and deploy my app the snippet of controllers/tab1.js creates a error msg table tab2 has no column named testString in "REPLACE INTO tab2.... To solve this I can clear the app's data and restart the app or by adding the code snippet of alloy.js.

1. Now I add the snippet from controllers/tab1.js to some other custom controller, e.g. controllers/mytest.js.
2. Empty the controllers/tab1.js file.
3. In this configuration I run into same issue described above when saveTestString() is executed, with the difference that the solution does not work at all.
4. Only if I add a record in controllers/tab1.js before I trying to add another records in controllers/mytest.js, then no error msg appears.

alloy.js

 var db = Ti.Database.open ('_alloy_');
 db.execute ('DROP TABLE IF EXISTS tab2;');
 db.close ();

controllers/tab1.js

(function() {
  let tab1 = Alloy.createModel('tab2', {"testString": "myString");
  tab1.save();
})();

function saveString(event){
 	Alloy.createController('myTest').getView().open();
}

views/index.xml

<Alloy>
	<TabGroup title="MyApp">
           <Require src="tab1" />
           <Require src="tab2" />
	</TabGroup>
</Alloy>

views/tab1.xml

<Alloy>
   <Tab id="tab1" title="Tab1">
    <Window id="window1" title="Window1" onClose="cleanup">
        <Menu>
        <MenuItem title="Save" onClick="saveString"/>
      </Menu>
    </Window>
   </Tab>
  </Alloy>

views/tab2.xml

<Alloy>
  <Collection src="tab2" />
   <Tab id="tab2" title="Tab2">
    <Window id="window2" title="Window2" onClose="cleanup">
    </Window>
   </Tab>
  </Alloy>

models/tab2.js

exports.definition = {
    config: {
        "columns": {
            "testString": "TEXT"
            "id": "INTEGER PRIMARY KEY AUTOINCREMENT"
        },
        "adapter": {
            "type": "sql",
            "collection_name": "tab2",
            "idAttribute": "id"
        }
     }
}

controllers/mytest.js

function saveTestString(){
  let tab1 = Alloy.createModel('tab2', {"testString": "myString");
  tab1.save();
}

views/mytest.xml

<Alloy>
    <Window id="saveTestString" title="New Test String" onClose="cleanup">
       <ActionBar id="actionbar" displayHomeAsUp="true" onHomeIconItemSelected="closeWindow" />
         <Menu>
           <MenuItem showAsAction="Ti.Android.SHOW_AS_ACTION_ALWAYS" title="Save" onClick="saveOpponent">
           </MenuItem>
        </Menu>
     </Window>
</Alloy>

[m1ga]

When I try to run your example code it just stops with

[ERROR] �� �Invalid <TabGroup> child type: Alloy.Require
[ERROR] �� �All <TabGroup> children must be <Tab> or <Menu> or <ActionBar>
[ERROR] �� �Alloy compiler failed

Which version of Alloy are you using?
And isn't the "error" just a warning? I remember those messages if you have a wrong migration file but it still worked. But it might be different in your case.

The "REPLACE" part is here: https://github.com/appcelerator/alloy/blob/28a239aa7fb1fdef2ac67e50d35780f5c9dd766d/Alloy/lib/alloy/sync/sql.js#L189 so it looks like it runs an update/sync and there it can't find the field. But I don't know why since I can't run the example.

[beppo-ivel]

When I try to run your example code it just stops with

It is not a complete working example. Please see the edits in the start post.

And isn't the "error" just a warning?

The Error is the same as described here

if you have a wrong migration file

I don't have migration file at all. But yes, u can say I don't have to clear app's data if I would define a migration file.

[m1ga]

so its just a dev thing on your device and if it is the same as that SO post the database was created before without the field. If so: just add your filed there or use something like https://stackoverflow.com/a/43524278 to add it later on.
All corrects answers are in you SO post :) It is in the device data once you've created it and the best way to update it is a migration or cleaning the data. If the drop doesn't work: are you creating the old structure again? Are you accessing it before the drop?
I wouldn't add too much time into that problem: if it is a new app, just clean the data or uninstall the app and create a new one. If it is a live app you want to update: create a migration!

[beppo-ivel]

I wouldn't add too much time into that problem: if it is a new app, just clean the data or uninstall the app and create a new one.

I agree. But there is one thing left I don't understand. If I delete the code snippet in controllers/tab1.js I run always into the described error above when saveTestString() from controllers/mytest.js is executed. The code in the self-executed-function and saveTestString is the same but only controllers/tab1.js is able to execute it and saveTestString() only executes without any error if the self-executed-function creates a record.