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POChained aggregate call across association in DataMapper (ruby)
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copied!<p>I am working on a simple budget app using Sinatra and DataMapper in Ruby.</p> <p>I want to get the sum of all transactions across all income accounts within the last 30 days.</p> <p>Something like <code>Account.income_accounts.account_entries.sum(:amount, :transaction_date.gte => Date.today - 30)</code> should work. Instead, the limiting condition on <code>transaction_date</code> is getting ignored, returning the sum of the amount for all entries for all income accounts.</p> <p>Given the following:</p> <pre><code>class Account include DataMapper::Resource has n, :account_entries property :id, Serial property :name, String property :acct_type, String def self.income_accounts all(:acct_type => 'Income') end end class AccountEntry include DataMapper::Resource belongs_to :account property :id, Serial property :account_id, Integer property :description, String property :amount, BigDecimal property :transaction_date, DateTime end </code></pre> <p>I am properly requiring <code>dm-aggregates</code>. I am new to DataMapper. If it matters, I am using a sqlite3 database. I really don't want to resort to using ruby to sum the results. It also feels wrong to resort to executing raw SQL for this type of simple aggregate query. </p> <p>Can anyone shed some light on this? I would love to be pointed in the right direction regarding chained finders in DataMapper, particularly with aggregates. My spelunking into the API and the DataMapper site hasn't yielded a solution as of yet.</p>

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