Sum of values in array of objects without reduce function

Designing Pipelines
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#1

Hello all,

I stumbled upon a situation where I have to find out a sum of a certain key in the objects residing in an array without reducing the objects? What I mean to say is, here is the input:

[
{
key1: value1,
key2: 10
},
{
key1: value2,
key2: 20
},
{
key1: value3,
key2: 30
}
]

The output that I am expecting should look like:

[
{
key1: value1,
key2: 10,
sum: 60
},
{
key1: value2,
key2: 20,
sum: 60
},
{
key1: value3,
key2: 30,
sum: 60
}
]

The total sum of key 2 values should be pushed into each object as a new key.

Can some one please suggest how to deal with this? Reducing won’t be the optimal solution as it would discard the objects and just add a new object with the total sum.

Thanks.

#2

This expression helped for now:
jsonPath($, “group[*]”).map(item => item.key2).reduce((prev, next) => prev + next)

Mapped this to field “sum” and pushed it into the array.

Is there any other way as well to achieve this?

#3

@Tanmay_Sarkar - I haven’t put an example together, but you should be able to do this with a combination of map() and reduce() functions. Looking at the full spec of the Array.map() function, you can access the array as one of the parameters:

1 Like
#4

You can use merge function too.

https://docs-snaplogic.atlassian.net/wiki/spaces/SD/pages/1439367/Object+Functions+and+Properties#ObjectFunctionsandProperties-merge

Community_Example_2021_05_11.slp (3.5 KB)

$group.map(x=>x.merge({“sum”:$group.map(item => item.key2).reduce((accum, currentValue) => accum + currentValue)}))

1 Like
#5

Hi @Tanmay_Sarkar,

You can also use Apache Velocity within JSON Generator. Here is the script:

#set($sum = 0)
#foreach ($field in $group)
#set($sum=$sum+$field.key2)
#end

#foreach($field in $group)
#set($dummy = $field.put(“sum”,$sum))
#end

{“group”:$group}

Regards,
Bojan

1 Like
#6

@skatpally Thanks a lot, this worked effortlessly.

#7

@bojanvelevski Thanks a lot, I never realized Apache Velocity can be used within JSON generator in such a way, this would come in handy in future.

#8

@koryknick Thanks a lot, eventually map and merge function helped.