Is it possible to create multiple draft items on createdatasource? - google-app-maker

Question

I am building an application that will have the ability to create agenda items to discuss in a meeting. The agenda item might include one or more attachments to discuss so there is a one to many relation between the AgendaItems and the AgendaDocs models. So far, I have an insert form that looks like this:
The "Select File" button is a drive picker and the code I have inside the onDocumentSelect event is the following:
var docs = result.docs;
var createDataSource = app.datasources.AgendaDocs.modes.create;
for(var i=0; i<docs.length-1; i++){
var uniqueDraft = createDataSource.item;
createDataSource.items.push(uniqueDraft);
}
for(var i=0; i<createDataSource.items.length-1; i++){
var draft = createDataSource.item;
createDataSource.items[i].DocTitle = docs[i].name;
createDataSource.items[i].DocURL = docs[i].url;
createDataSource.items[i].DriveID = docs[i].id;
}
console.log(createDataSource.items);
The code is supposed to fill out the the List widget below the "Select File" button, but as how you see, the three items are the same. The datasource of the List widget is "AgendaDocs.modes.create" and the datasource of the insert form is "AgendaItems.modes.create".
Reading the official documentation from appmaker, makes me think it is possible since the properties of "CreateDataSource" includes "items". I need help from an expert here. Is this possible? Am I using the wrong approach?

Answer 1

First things first, it seems that you are trying to create records from different models and relationship between them in a one call... at this time App Maker is not that smart to digest such a complex meal. Most likely you'll need to break your flow into multiple steps:
Create (persist) Agenda Item
Create AgendaDocs records and relation with AgendaItem
Similar flow is implemented in Travel Approval template app, but it is not exactly the same as yours, since it doesn't create associations in batches.
Going back to the original question. Yep, it is possible to have multiple drafts, but not with the Create Datasource. You are looking for Manual Save Mode. Somewhere in perfect world your code would look similar to this:
// AgendaItems in Manual Save mode
var agendaDs = app.datasources.AgendaItems;
// this line will create item on client and automatically push it
// to ds.items and set ds.item to it.
agendaDs.createItem();
var agendaDraft = agendaDs.item;
// Field values can be populated from UI via bindings...
agendaDraft.Type = 'X';
agendaDraft.Description = 'Y';
// onDocumentSelect Drive Picker's event handler
var docsDs = agendaDs.relations.AgendaDocs;
result.docs.forEach(function(doc) {
// this line will create item on client and automatically push it
// to ds.items and set ds.item to it...however it will throw an exception
// with this message:
// Cannot save a foreign key association for the 'AgendaItem'
// relation because the target record has not been persisted
// to the server. To fix this, call saveChanges()
// on the data source for that record's model: AgendaItem
docsDs.createItem();
var docDraft = docsDs.item;
docDraft.DocTitle = doc.name;
docDraft.DocURL = doc.url;
docDraft.DriveID = doc.id;
});
// submit button click
agendaDraft.saveChanges();