Struct datafusion_common::scalar::ScalarStructBuilder

pub struct ScalarStructBuilder { /* private fields */ }

Builder for ScalarValue::Struct.

See examples on ScalarValue

Implementations

impl ScalarStructBuilder

pub fn new() -> Self

Create a new ScalarStructBuilder

pub fn new_null(fields: impl IntoFields) -> ScalarValue

Return a new ScalarValue::Struct with a single null value.

Note this is different from a struct where each of the specified fields are null (e.g. {a: NULL})

Example

let fields = vec![
   Field::new("a", DataType::Int32, false),
];
let sv = ScalarStructBuilder::new_null(fields);
// Note this is `NULL`, not `{a: NULL}`
assert_eq!(format!("{sv}"), "NULL");

To create a struct where the fields are null, use Self::new() and pass null values for each field:

// make a nullable field
let field = Field::new("a", DataType::Int32, true);
// add a null value for the "a" field
let sv = ScalarStructBuilder::new()
  .with_scalar(field, ScalarValue::Int32(None))
  .build()
  .unwrap();
// value is not null, but field is
assert_eq!(format!("{sv}"), "{a:}");

pub fn with_array(self, field: impl IntoFieldRef, value: ArrayRef) -> Self

Add the specified field and ArrayRef to the struct.

Note the array should have a single row.

pub fn with_scalar(self, field: impl IntoFieldRef, value: ScalarValue) -> Self

Add the specified field and ScalarValue to the struct.

pub fn with_name_and_scalar(self, name: &str, value: ScalarValue) -> Self

Add a field with the specified name and value to the struct. the field is created with the specified data type and as non nullable

pub fn build(self) -> Result<ScalarValue>

Return a ScalarValue::Struct with the fields and values added so far

Errors

If the StructArray cannot be created (for example if there is a mismatch between field types and arrays) or the arrays do not have exactly one element.

Trait Implementations

impl Debug for ScalarStructBuilder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ScalarStructBuilder

fn default() -> ScalarStructBuilder

Returns the “default value” for a type.