Hi Clojure Users,
I wanted to learn an idiomatic approach to data transformation in Clojure.
For example I have a web service that is consuming some ReST services,
Ultimately I need to consolidate these services into a data model which
resembles a DAG. However I would like to transform the children of this
data model in discrete transformation functions that may share some logic
and the transforming functions should be able to handle nulls and fail or
exit gracefully. I have provided a simple example below. I would
appreciate any links to existing code and especially any links that include
background or theory on the matter. Bonus points if some examples use
functors or monads or other interesting concepts.
Here's an example, using the two input sources, consolidate into a new data
model. In the output json I have highlighted some common transformation
points such as dates and currencies. My understanding is that a pure
function take on this would be just a function per mapping pair. So for
any given item in the output set map a function to the items in the input
set. But what other clever tricks can be applied and what would this look
like?
Thanks so much for your help on this!
Input data (json) for apples:
{
"fruit-category" : "apple",
"fruit-category-id": "2001",
"fruit-items": [
{
"fruit-item-id": "2001-1",
"description": "Fuji",
"current-price": "3.01",
"currency": "USD",
"fresh-until": "2015/07/16"
},
{
"fruit-item-id": "2001-2",
"description": "Honeycrisp",
"current-price": "1.69",
"currency": "USD",
"fresh-until": "2015/07/17"
}]
}
Input data (json) for oranges:
{
"fruit-category" : "orange",
"fruit-category-id": "2002",
"fruit-items": [
{
"fruit-item-id": "2002-1",
"description": "Mandarin",
"current-price": "1.88",
"currency": "USD",
"fresh-until": "2015/07/19"
},
{
"fruit-item-id": "2002-2",
"description": "Clementine",
"current-price": "1.98",
"currency": "USD",
"fresh-until": "2015/07/13"
}]
}
Consolidated output data (json):
{
"fruit-basket": {
"title": "Apples and Oranges",
"price": "17.12",
"currency": "USD",
"converted-currency":"JPY",
"converted-price":"2098.22",
"fresh-until":"2015/07/13",
},
"items": [{
"fruit-item-id":"2001-1",
"qty": "2",
}, {
"fruit-item-id":"2001-2",
"qty": "2",
}, {
"fruit-item-id":"2002-1",
"qty": "2",
}, {
"fruit-item-id":"2002-1",
"qty": "2",
}],
"entities": [
{
"fruit-item-id": "2001-1",
"description": "Fuji",
"current-price": "3.01",
"currency": "USD",
"fresh-until": "2015/07/16"
},
{
"fruit-item-id": "2001-2",
"description": "Honeycrisp",
"current-price": "1.69",
"currency": "USD",
"fresh-until": "2015/07/17"
},
{
"fruit-item-id": "2002-1",
"description": "Mandarin",
"current-price": "1.88",
"currency": "USD",
"fresh-until": "2015/07/19"
},
{
"fruit-item-id": "2002-2",
"description": "Clementine",
"current-price": "1.98",
"currency": "USD",
"fresh-until": "2015/07/13"
}
],
"extra-stuff": {
"cache-key": "foo",
"other-data": "bar",
"timestamp-utc": "..."
}
}
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