Added variable doc

This commit is contained in:
Mike Farah 2021-02-04 12:44:03 +11:00
parent 691efadfac
commit 3a464272d4
3 changed files with 62 additions and 1 deletions

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@ -0,0 +1,58 @@
For more complex scenarios, variables can be used to hold values of expression to be used in other expressions.
## Single value variable
Given a sample.yml file of:
```yaml
a: cat
```
then
```bash
yq eval '.a as $foo | $foo' sample.yml
```
will output
```yaml
cat
```
## Multi value variable
Given a sample.yml file of:
```yaml
- cat
- dog
```
then
```bash
yq eval '.[] as $foo | $foo' sample.yml
```
will output
```yaml
cat
dog
```
## Using variables as a lookup
Example taken from [jq](https://stedolan.github.io/jq/manual/#Variable/SymbolicBindingOperator:...as$identifier|...)
Given a sample.yml file of:
```yaml
"posts":
- "title": Frist psot
"author": anon
- "title": A well-written article
"author": person1
"realnames":
"anon": Anonymous Coward
"person1": Person McPherson
```
then
```bash
yq eval '.realnames as $names | .posts[] | {"title":.title, "author": $names[.author]}' sample.yml
```
will output
```yaml
title: Frist psot
author: Anonymous Coward
title: A well-written article
author: Person McPherson
```

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For more complex scenarios, variables can be used to hold values of expression to be used in other expressions.

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@ -23,7 +23,8 @@ var variableOperatorScenarios = []expressionScenario{
},
},
{
description: "Using variables as a lookup",
description: "Using variables as a lookup",
subdescription: "Example taken from [jq](https://stedolan.github.io/jq/manual/#Variable/SymbolicBindingOperator:...as$identifier|...)",
document: `{"posts": [{"title": "Frist psot", "author": "anon"},
{"title": "A well-written article", "author": "person1"}],
"realnames": {"anon": "Anonymous Coward",
@ -40,4 +41,5 @@ func TestVariableOperatorScenarios(t *testing.T) {
for _, tt := range variableOperatorScenarios {
testScenario(t, &tt)
}
documentScenarios(t, "Variable Operators", variableOperatorScenarios)
}