Rails data modelling with has_many through

Hi,

I am building an expense tracker application and I am in middle of data
modelling. I have a Users table. Each user will log his expenses with
expense type and income with income type. So I need to know how can we
set
up associations for it.

I have User, Expense, Income and UserTransaction models.

Expense and Income will have following fields

  • id, date, category, amount, description, user_id, currency*

I am not sure whether I need UserTransaction table also.
But my business requirement is as follows

I should be able to get all expenses/income of a user with date range
and
also with category

I should also be able to get all transactions occurred with date range.

On 31 August 2015 at 15:47, Pradeep A. [email protected]
wrote:

I notice that the last time you asked basically the same question you
did not appear to reply or offer thanks for the help offered, which is
not good manners, unless I missed the post. However I will try to
help again. See below,

id, date, category, amount, description, user_id, currency

There is a big clue there. If two tables have the same fields then
almost certainly it should just be one table. Possibly call it
transactions and use different categories to distinguish between
income and expenses.

I am not sure whether I need UserTransaction table also.
But my business requirement is as follows

I should be able to get all expenses/income of a user with date range and
also with category

I should also be able to get all transactions occurred with date range.

I also don’t see any need for a UserTransaction table. I think you
just need User has_many transactions, Transaction belongs_to user.

Colin

Hi Colin,

First of all Sorry for neglecting the previous comments. I didnt notice
that i had reply for the previous posts which I posted. Thats the reason
I
posted it once again here.
Thanks for your suggestions.

BTW I was thinking whether polymorphic association would really be nice
for
my scenario

I would look into the concept of a single table inheritance for a
transactions table…you’d have to add an extra attribute/column that
would
be ‘transaction’ type to indicate whether it’s an expense or income, but
this should be able to be done with a simple 1 to many relationship - a
user has many transactions - Single Table Inheritance is great for
things
like this and Rails handles it very easily.

On 31 August 2015 at 19:12, John L. [email protected] wrote:

I would look into the concept of a single table inheritance for a
transactions table…you’d have to add an extra attribute/column that would
be ‘transaction’ type to indicate whether it’s an expense or income, but
this should be able to be done with a simple 1 to many relationship - a user
has many transactions - Single Table Inheritance is great for things like
this and Rails handles it very easily.

Whether the added complication of STI is worth the benefits in this
case depends on what code differences there are between income and
expenses. I would start off with the simple solution and if it
becomes apparent that STI would be beneficial then refactor it at that
point.

Colin

On 31 August 2015 at 18:29, prabhu [email protected] wrote:

Hi Colin,

First of all Sorry for neglecting the previous comments. I didnt notice that
i had reply for the previous posts which I posted. Thats the reason I posted
it once again here.
Thanks for your suggestions.

BTW I was thinking whether polymorphic association would really be nice for
my scenario

Why? What advantage would that have over the simple setup I suggested?

Colin

On 31 August 2015 at 18:29, prabhu [email protected] wrote:

Hi Colin,

First of all Sorry for neglecting the previous comments. I didnt notice that
i had reply for the previous posts which I posted. Thats the reason I posted
it once again here.
Thanks for your suggestions.

I notice, looking back through your previous posts over more than a
year you have rarely responded to replies here.

Colin

Dear Colin,

I think that what you are broaching is an ethical matter in the use of
this
Talk Group. Generally folks cheating, as students or incompetent
employees.

Where and when does one choose not to help.

Liz

It would be nice if this thread got back on topic with the OPs problem.
We are all here to help.

Sent from my iPhone

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