Ledgers
A ledger is a table of numbers that you can save in a case, and access in forms.
Definitions:
- A ledger can be viewed as a type of case property
- But unlike the case property the ledgers can be updated directly in the form-builder with the transactions.
- The row of the ledger is called an "entry" and corresponds to a product id.
- The column of a ledger is called a "section":
- You can create your own section when creating a ledger (stock, balance, price, order amounts ...)
- You can define as many sections as you want for a ledger.
- Some section ids, such as consumption (which store the average monthly consumption) are reserved by the application.
- The number saved for each row and column is called a "quantity":
- The quantities of a ledger are of integer type. Decimals are not supported.
Do you want to use a ledger?
- You are a community health worker who manages ORS, zinc, and vitamins
- You are building an app to track shipments of products over time
- You are building an app to track orders/requisitions of products over time
- You want to track the number of Rapid Diagnostic Tests (RDTs) at a facility over time
- You want to make a sandwich shop app that tracks how much money 50 different clients owe you
Transactions
A transaction allow you to save and update numbers in a ledger.
There are 4 types of transactions:
- Balance: set the ledger quantity to a specific value
- Receive: increment the ledger quantity by a specific value
- Dispense: decrement the ledger quantity by a specific value
- Transfer: decrement the ledger quantity by a specific value on a case A & increment the ledger quantity by a specific value on a case B
Good to know !!!
- Transactions are atomic – so if your phone shuts down mid-transfer, things don’t get lost.
- Transactions are also resolved meaningfully. In CommCare, if 2 phones increments the same number, whichever phone writes last wins. In CommCare Supply, the increments are summed.
How to setup a transaction question?
- Question ID: anything you want
- Case: id of the case where your ledger will be saved.
- This can take different values depending on which case you want to use to save your ledger.
- In order to save the ledger in the current selected case, use: instance('commcaresession')/session/data/case_id.
- In order to save the ledger in the user supply-point, use: instance('commcaresession')/session/user/data/commtrack-supply-point.
- ...
- Balance ID: id of the section (i.e. stock, balance, ...)
- Product: id of the product
- When used in a repeat group over products, the syntax to use is current()/../../../@id. However this will depend if you put the transaction question in question groups or not (see here).
- Quantity: value to set to the ledger.