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Better merge array by key example

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Mike Farah 2021-11-29 20:46:12 +11:00
parent 8c5d1e0252
commit 51e946e6ff
2 changed files with 16 additions and 12 deletions
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14
pkg/yqlib/doc/multiply-merge.md
View File

@ -234,11 +234,8 @@ will output
```
## Merge arrays of objects together, matching on a key
It's a complex command, the trickyness comes from needing to have the right context in the expressions.
First we save the second array into a variable '$two' which lets us reference it later.
We then need to update the first array. We will use the relative update (|=) because we need to update relative to the current element of the array in the LHS in the RHS expression.
We set the current element of the first array as $cur. Now we multiply (merge) $cur with the matching entry in $two, by passing $two through a select filter.
There are two parts of the complex expression. The first part is doing the hard work, it creates a map from the arrays keyed by '.a',
so that there are no duplicates. The second half converts that map back to an array.
Given a sample.yml file of:
```yaml
@ -260,7 +257,10 @@ And another sample another.yml file of:
```
then
```bash
yq eval-all '(select(fi==1) | .[]) as $two | select(fi==0) | .[] |= (. as $cur | $cur * ($two | select(.a == $cur.a)))' sample.yml another.yml
yq eval-all '
((.[] | {.a: .}) as $item ireduce ({}; . * $item )) as $uniqueMap
| ( $uniqueMap | to_entries | .[]) as $item ireduce([]; . + $item.value)
' sample.yml another.yml
```
will output
```yaml
@ -271,6 +271,8 @@ will output
- a: banana
b: bananaB
c: bananaC
- a: dingo
c: dingoC
```
## Merge to prefix an element

14
pkg/yqlib/operator_multiply_test.go
View File

@ -29,10 +29,12 @@ var mergeArrayWithAnchors = `sample:
- <<: *a
`
var mergeArraysObjectKeysText = `It's a complex command, the trickyness comes from needing to have the right context in the expressions.
First we save the second array into a variable '$two' which lets us reference it later.
We then need to update the first array. We will use the relative update (|=) because we need to update relative to the current element of the array in the LHS in the RHS expression.
We set the current element of the first array as $cur. Now we multiply (merge) $cur with the matching entry in $two, by passing $two through a select filter.
var mergeArraysObjectKeysText = `There are two parts of the complex expression. The first part is doing the hard work, it creates a map from the arrays keyed by '.a',
so that there are no duplicates. The second half converts that map back to an array.`
var mergeExpression = `
((.[] | {.a: .}) as $item ireduce ({}; . * $item )) as $uniqueMap
| ( $uniqueMap | to_entries | .[]) as $item ireduce([]; . + $item.value)
`
var docWithHeader = `# here
@ -373,9 +375,9 @@ var multiplyOperatorScenarios = []expressionScenario{
subdescription: mergeArraysObjectKeysText,
document: `[{a: apple, b: appleB}, {a: kiwi, b: kiwiB}, {a: banana, b: bananaB}]`,
document2: `[{a: banana, c: bananaC}, {a: apple, b: appleB2}, {a: dingo, c: dingoC}]`,
expression: `(select(fi==1) | .[]) as $two | select(fi==0) | .[] |= (. as $cur | $cur * ($two | select(.a == $cur.a)))`,
expression: mergeExpression,
expected: []string{
"D0, P[], (doc)::[{a: apple, b: appleB2}, {a: kiwi, b: kiwiB}, {a: banana, b: bananaB, c: bananaC}]\n",
"D0, P[], (!!seq)::- {a: apple, b: appleB2}\n- {a: kiwi, b: kiwiB}\n- {a: banana, b: bananaB, c: bananaC}\n- {a: dingo, c: dingoC}\n",
},
},
{