Conditionals

Conditionals allow you to select different values depending on an expression. Dasel v3 supports both a long form if/else block and a compact ternary operator.

---

Long Form (if/else)

The long form is more explicit and easier to read for complex conditions.

if (<condition>) { <then-expression> } else { <else-expression> }

• <condition> must evaluate to a boolean.

• <then-expression> is evaluated if the condition is true.

• <else-expression> is evaluated if the condition is false.

Example

Input JSON

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

Query

$ dasel -i json -f input.json '.foo.if(bar == "baz") { bong } else { qux }'

Output

selected

---

Ternary Operator (? :)

Not yet implemented.

The ternary form is shorter and useful for inline conditions.

<condition> ? <then-expression> : <else-expression>

Example

Input JSON

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

Query

$ dasel -i json -f input.json '.foo.(bar == "baz" ? bong : qux)'

Output

not-selected

---

Literals and Nesting

Both forms support literals and nested expressions.

Example 1: Literal results

Input JSON

{ "count": 7 }

Query

$ dasel -i json -f input.json 'if(count > 5) { "many" } else { "few" }'

Output

many

---

Example 2: Nested ternaries

Input JSON

{ "foo": { "bar": "zap", "bong": "BONG", "qux": "QUX", "zap": "ZAP", "default": "DEF" } }

Query

$ dasel -i json -f input.json '.foo.(bar == "baz" ? bong : (bar == "qux" ? qux : default))'

Output

DEF

---

Notes

• An else branch is required. Both the if/else and ternary forms must specify an else result.

• Both branches must return a value. A conditional always evaluates to a result — you cannot have an empty branch.

• Parentheses are recommended when nesting conditionals.

• Both branches must be valid dasel expressions (selectors, literals, or functions).