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 (?:).

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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.

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Basic Example

Input JSON

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

Query

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

Output

"selected"

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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

{ "score": 75 }

Query

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:

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

$ 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
    }
)'

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Literal Results

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

Input JSON

{ "count": 7 }

Query

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

Output

"many"

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Nested Conditionals

Conditionals can be nested in the else branch.

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.

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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

{ "age": 25 }

Query

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

Output

"adult"

Nested Ternary

Parentheses can be used to nest ternary expressions.

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

Output

"b"

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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.