The Money Gopher

The Money Gopher will help you to keep track of your investments.

Why?

Surely, there are a number of programs and services out there that already manage your portfolio(s), why creating another one? Well there are several reasons or rather requirements that I have. Note, that these might be very specific to my use-case, but maybe somebody else will appreciate them as well.

• 🏘️ I need to manage several portfolios for several distinct people, for example my own and my children's. I want to keep these portfolios completely separate, but still manageable within the same uniform UI or program. For a lack of better term, I call this a "portfolio group" for now.
• 💵 All "portfolio groups" could share stock information, such as buy/sell prices and meta-data. Then they only need to be retrieved once and are available to all "groups".
• 🤑 Within one "portfolio group", I obviously want to manage several portfolios, displaying certain performance values (e.g. absolute gain, time-weighted return, etc.) per portfolio and for the whole group.
• 📱 I want to access this information from multiple devices, e.g., my laptop, my tablet and my phone. But, I don't necessarily need this information on the go, so having some kind of "server" locally to my network and a browser-based UI seems to be perfect. This means that the UI tech stack should reflect responsiveness and a mobile-friendly design. If I really need this information on the go, I could then still set this up on a server that I own or VPN to my home network.
• 👨‍💻 I love APIs, so having access to this in a RPC or REST API would be awesome. It is anyway needed for the UI. Maybe also a simple CLI for quick tasks, such as triggering a refresh of stock information would also be nice.

Furthermore, there are some personal technical motivations that drove me to creating this.

• 📞 I wanted to explore new ways of providing RPC-style APIs that are not based on the arguably bloated gRPC framework. Therefore, I am exploring Buf's Connect framework in this project, which seems promising, even for browser-based interactions.
• 🔲 I am still on the spiritual search for a good UI framework, so this might be a good chance to explore different options.
• 📈 I wanted to understand the math behind some of the used performance models, such as time-weighted rate of return a little bit better.

Usage

This project has currently three main components:

• A server component moneyd, which manages the connection to the database and offers a RPC-API using Connect to manage portfolios and securities.
• A simple CLI mgo which can be used to interact with the API.
• An even simpler web-based user interface, based on SvelteKit.

Starting moneyd

After checking out the source-code, the necessary Go binaries can be compiled using go build ./cmd/moneyd and can be started using ./moneyd. It will print out some information, but logging definitely needs to improved.

On startup, an SQLite database named money.db will be created (or loaded) in the same directory as the started binary. If the database is empty, a new portfolio named mybank/myportfolio and one example security will be created.

As a simple check, one can simply interact with the RPC-API with a normal HTTP client, for example to list all portfolios.

curl \
  --header 'Content-Type: application/json' \
  --data '{}' \
  http://localhost:8080/mgo.portfolio.v1.PortfolioService/ListPortfolios

This should print something like the following.

{"portfolios":[{"name":"bank/myportfolio","displayName":"My Portfolio"}]}

Using mgo

Alternatively, a simple CLI called mgo can be used. It is preferable to install it for the current user using go install ./cmd/mgo. Afterwards, it can for example used to display all portfolios with mgo portfolio list.

Adding Transactions

To add transactions (buy, sell, etc.) to an existing portfolio, the command mgo portfolio transaction create can be used. The following shows an example for the security with the ISIN US0378331005.

mgo portfolio transactions create US0378331005 --portfolio-name bank/myportfolio --amount 5 --price 120 --time="2022-01-01 10:00"

When successful, this should print something like the following.

The unique identifier (also called 'name') of the transaction can be used in other calls, e.g., to modify it.

Available Commands and Shell Completion

For a detailed list of all available commands see mgo --help. The CLI also supports (basic) shell completion. For details how to activate it, please see mgo completion.

When is it finished?

Since I am working on this in my spare time, it will probably take a while 😃.