[Feature] Split a transaction

[grablair]

Add the ability to split a transaction

[jprouty]

I was exploring the web app today to map out the relevant graphgl queries. Here's what I see:

• GetTransactionsList - once split, the list contains only the split transactions which are denoted with isSplitTransaction: True member. There is no transaction member that indicates the parent transaction id (originalTransaction as MM likes to call it).
• GetTransactionDrawer - for split transactions, this query returns detailed per-transaction members to populate the drawer/side bar in the web app. Once a transaction is split, I cannot find a place in the UI such that the original transaction is shown again (unless you unsplit it - see below). The hasSplitTransactions: <bool> and splitTransactions: [] members seem to indicate that if given a parent id as the query id it would return all splits; this isn't particularly useful because the UI invokes another query, described below, for getting all of the splits for a given transaction id. Importantly, this call does indicate the parent transactions by including the originalTransaction member (real example):

"data": {
    "getTransaction": {
        "id": "123childID321", <- Fake
        ...other transaction members...
        "hasSplitTransactions": false,
        "isSplitTransaction": true,
        "splitTransactions": [],
        "originalTransaction": {
            "id": "123parentID321", <- Fake
            "date": "2024-01-02",
            "amount": -100.0,
            "merchant": {
                "id": "12321", <- Fake
                "name": "Test",
                "__typename": "Merchant"
            },
            "__typename": "Transaction"
        }
    }
}

• TransactionSplitQuery - the UI invokes this query when bringing up the split dialog (which allows for creating, adjusting, deleting splits). Given the parent transaction id, returns a list of transaction ids that are the children splits.
• SplitTransactionMutation - query for creating, modifying, deleting splits. All operate on the parent transaction id and are given a splitData array for how to divide the transaction. From the UI, you can only provide the new amount, merchantName, and category. If the parent transaction already has a note (or I imagine also tags - to be verified), these are cloned onto each split transaction automagically.

Deleting is the simplest: given the parent transaction id and splitData=[], delete all children transactions and return the parent transaction as the only transaction.

Creating and modifying splits are the same: given the parent transaction id and splitData=[...children splits...], where sum([s.amount for split in splitData]) == parentTranasction.amount, creates len(splitData) new transactions that are displayed in the UI in place of the parentTranasction; if parentTranasction already had splitTransactions, then replace those with the new splitData.

Next step I am translating the network captures I've made into a working version and will create a PR once things look right.

[hammem]

@grablair , can you confirm @jprouty 's PR addresses this issue?

[grablair]

I believe it does. We can close this and open another one if someone discovers we are missing something.