yq/pkg/yqlib/doc/Encoder and Decoder.md
2021-10-22 15:21:01 +11:00

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Encode operators will take the piped in object structure and encode it as a string in the desired format. The decode operators do the opposite, they take a formatted string and decode it into the relevant object structure.
These operators are useful to process yaml documents that have stringified embeded yaml/json/props in them.
## Encode value as yaml string
Given a sample.yml file of:
```yaml
a:
cool: thing
```
then
```bash
yq eval '.b = (.a | to_yaml)' sample.yml
```
will output
```yaml
a:
cool: thing
b: |
cool: thing
```
## Encode value as yaml string, using toyaml
Does the same thing as to_yaml, matching jq naming convention.
Given a sample.yml file of:
```yaml
a:
cool: thing
```
then
```bash
yq eval '.b = (.a | to_yaml)' sample.yml
```
will output
```yaml
a:
cool: thing
b: |
cool: thing
```
## Encode value as json string
Given a sample.yml file of:
```yaml
a:
cool: thing
```
then
```bash
yq eval '.b = (.a | to_json)' sample.yml
```
will output
```yaml
a:
cool: thing
b: |
{
"cool": "thing"
}
```
## Encode value as props string
Given a sample.yml file of:
```yaml
a:
cool: thing
```
then
```bash
yq eval '.b = (.a | to_props)' sample.yml
```
will output
```yaml
a:
cool: thing
b: |
cool = thing
```
## Decode a yaml encoded string
Given a sample.yml file of:
```yaml
a: 'foo: bar'
```
then
```bash
yq eval '.b = (.a | from_yaml)' sample.yml
```
will output
```yaml
a: 'foo: bar'
b:
foo: bar
```
## Update a multiline encoded yaml string
Given a sample.yml file of:
```yaml
a: |
foo: bar
baz: dog
```
then
```bash
yq eval '.a |= (from_yaml | .foo = "cat" | to_yaml)' sample.yml
```
will output
```yaml
a: |
foo: cat
baz: dog
```
## Update a single line encoded yaml string
Given a sample.yml file of:
```yaml
a: 'foo: bar'
```
then
```bash
yq eval '.a |= (from_yaml | .foo = "cat" | to_yaml)' sample.yml
```
will output
```yaml
a: 'foo: cat'
```