yq/operators/has.md

# Has

This is operation that returns true if the key exists in a map (or index in an array), false otherwise.

## Has map key

Given a sample.yml file of:

```yaml
- a: yes
- a: ~
- a:
- b: nope
```

then

```bash
yq eval '.[] | has("a")' sample.yml
```

will output

```yaml
true
true
true
false
```

## Select, checking for existence of deep paths

Simply pipe in parent expressions into `has`

Given a sample.yml file of:

```yaml
- a:
    b:
      c: cat
- a:
    b:
      d: dog
```

then

```bash
yq eval '.[] | select(.a.b | has("c"))' sample.yml
```

will output

```yaml
a:
  b:
    c: cat
```

## Has array index

Given a sample.yml file of:

```yaml
- []
- [1]
- [1, 2]
- [1, null]
- [1, 2, 3]
```

then

```bash
yq eval '.[] | has(1)' sample.yml
```

will output

```yaml
false
false
true
true
true
```