mirror of https://github.com/mikefarah/yq.git
140 lines
2.2 KiB
Markdown
140 lines
2.2 KiB
Markdown
# Select
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Select is used to filter arrays and maps by a boolean expression.
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## Related Operators
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- equals / not equals (`==`, `!=`) operators [here](https://mikefarah.gitbook.io/yq/operators/equals)
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- comparison (`>=`, `<` etc) operators [here](https://mikefarah.gitbook.io/yq/operators/compare)
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- boolean operators (`and`, `or`, `any` etc) [here](https://mikefarah.gitbook.io/yq/operators/boolean-operators)
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## Select elements from array using wildcard prefix
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Given a sample.yml file of:
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```yaml
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- cat
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- goat
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- dog
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```
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then
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```bash
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yq '.[] | select(. == "*at")' sample.yml
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```
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will output
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```yaml
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cat
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goat
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```
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## Select elements from array using wildcard suffix
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Given a sample.yml file of:
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```yaml
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- go-kart
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- goat
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- dog
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```
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then
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```bash
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yq '.[] | select(. == "go*")' sample.yml
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```
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will output
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```yaml
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go-kart
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goat
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```
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## Select elements from array using wildcard prefix and suffix
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Given a sample.yml file of:
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```yaml
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- ago
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- go
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- meow
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- going
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```
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then
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```bash
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yq '.[] | select(. == "*go*")' sample.yml
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```
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will output
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```yaml
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ago
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go
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going
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```
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## Select elements from array with regular expression
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See more regular expression examples under the [`string` operator docs](https://mikefarah.gitbook.io/yq/operators/string-operators).
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Given a sample.yml file of:
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```yaml
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- this_0
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- not_this
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- nor_0_this
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- thisTo_4
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```
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then
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```bash
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yq '.[] | select(test("[a-zA-Z]+_[0-9]$"))' sample.yml
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```
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will output
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```yaml
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this_0
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thisTo_4
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```
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## Select items from a map
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Given a sample.yml file of:
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```yaml
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things: cat
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bob: goat
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horse: dog
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```
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then
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```bash
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yq '.[] | select(. == "cat" or test("og$"))' sample.yml
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```
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will output
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```yaml
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cat
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dog
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```
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## Use select and with_entries to filter map keys
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Given a sample.yml file of:
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```yaml
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name: bob
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legs: 2
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game: poker
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```
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then
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```bash
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yq 'with_entries(select(.key | test("ame$")))' sample.yml
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```
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will output
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```yaml
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name: bob
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game: poker
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```
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## Select multiple items in a map and update
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Note the brackets around the entire LHS.
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Given a sample.yml file of:
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```yaml
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a:
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things: cat
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bob: goat
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horse: dog
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```
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then
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```bash
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yq '(.a.[] | select(. == "cat" or . == "goat")) |= "rabbit"' sample.yml
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```
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will output
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```yaml
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a:
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things: rabbit
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bob: rabbit
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horse: dog
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```
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