mirror of https://github.com/mikefarah/yq.git
57 lines
1.1 KiB
Markdown
57 lines
1.1 KiB
Markdown
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# Error
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Use this operation to short-circuit expressions. Useful for validation.
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{% hint style="warning" %}
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Note that versions prior to 4.18 require the 'eval/e' command to be specified. 
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`yq e <exp> <file>`
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{% endhint %}
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## Validate a particular value
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Given a sample.yml file of:
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```yaml
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a: hello
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```
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then
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```bash
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yq 'select(.a == "howdy") or error(".a [" + .a + "] is not howdy!")' sample.yml
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```
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will output
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```bash
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Error: .a [hello] is not howdy!
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```
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## Validate the environment variable is a number - invalid
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Running
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```bash
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numberOfCats="please" yq --null-input 'env(numberOfCats) | select(tag == "!!int") or error("numberOfCats is not a number :(")'
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```
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will output
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```bash
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Error: numberOfCats is not a number :(
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```
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## Validate the environment variable is a number - valid
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`with` can be a convenient way of encapsulating validation.
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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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favouriteAnimal: cat
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```
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then
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```bash
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numberOfCats="3" yq '
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with(env(numberOfCats); select(tag == "!!int") or error("numberOfCats is not a number :(")) |
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.numPets = env(numberOfCats)
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' 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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favouriteAnimal: cat
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numPets: 3
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```
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