# Conditionals

Conditionals allow you to select different values depending on an expression. Dasel v3 supports an `if/elseif/else` block syntax and a ternary operator (`?:`).

***

### Syntax

```
if (<condition>) { <then> } else { <else> }
```

* `<condition>` must evaluate to a boolean.
* `<then>` is evaluated if the condition is true.
* `<else>` is evaluated if the condition is false.
* An `else` branch is always required.

***

### Basic Example

**Input JSON**

```json
{
  "foo": {
    "bar": "baz",
    "bong": "selected",
    "qux": "not-selected"
  }
}
```

**Query**

```bash
echo '{"foo":{"bar":"baz","bong":"selected","qux":"not-selected"}}' | dasel -i json 'foo.if (bar == "baz") { bong } else { qux }'
```

**Output**

```
"selected"
```

***

### Elseif Chains

Use `elseif` to chain multiple conditions. You can use as many `elseif` branches as needed.

```
if (<condition1>) { <result1> } elseif (<condition2>) { <result2> } else { <default> }
```

#### Example

**Input JSON**

```json
{ "score": 75 }
```

**Query**

```bash
echo '{"score": 75}' | dasel -i json '
  if (score >= 90) { "A" }
  elseif (score >= 80) { "B" }
  elseif (score >= 70) { "C" }
  else { "F" }
'
```

**Output**

```
"C"
```

#### Fizzbuzz with elseif

Given `numbers.json`:

```json
{ "numbers": [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15] }
```

```bash
$ cat numbers.json | dasel -i json 'numbers.map(
    if ($this % 3 == 0 && $this % 5 == 0) {
        "fizzbuzz"
    } elseif ($this % 5 == 0) {
        "buzz"
    } elseif ($this % 3 == 0) {
        "fizz"
    } else {
        $this
    }
)'
```

***

### Literal Results

Both branches can return literal values, not just field lookups.

**Input JSON**

```json
{ "count": 7 }
```

**Query**

```bash
echo '{"count": 7}' | dasel -i json 'if (count > 5) { "many" } else { "few" }'
```

**Output**

```
"many"
```

***

### Nested Conditionals

Conditionals can be nested in the `else` branch.

```bash
echo '{"status": "pending"}' | dasel -i json '
  if (status == "active") { "go" }
  else { if (status == "pending") { "wait" } else { "stop" } }
'
```

For multi-branch cases, `elseif` is cleaner than nesting.

***

## Ternary Operator

The ternary operator provides a compact inline syntax for conditionals.

### Syntax

```
<condition> ? <then> : <else>
```

* `<condition>` must evaluate to a boolean.
* `<then>` is returned when the condition is true.
* `<else>` is returned when the condition is false.

### Example

**Input JSON**

```json
{ "age": 25 }
```

**Query**

```bash
echo '{"age": 25}' | dasel -i json 'age >= 18 ? "adult" : "minor"'
```

**Output**

```
"adult"
```

### Nested Ternary

Parentheses can be used to nest ternary expressions.

```bash
echo '{}' | dasel -i json 'true ? (false ? "a" : "b") : "c"'
```

**Output**

```
"b"
```

***

### Notes

* An `else` branch is always required — both `if/else` and `if/elseif/else` must have a final `else`.
* Both branches must return a value — you cannot have an empty branch.
* Use `elseif` (one word, no space) for chained conditions.
* Parentheses around the condition are required for `if`/`elseif` blocks but not for the ternary operator.
* The ternary operator always requires both `?` and `:` parts.


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