Struct Value 

pub struct Value { /* private fields */ }

A PVAccess value container

Represents a structured data value returned from PVXS operations. Values have a hierarchical structure with named fields.

Field Access

Values are accessed by field name. Common fields include:

• "value": The primary data value
• "alarm.severity": Alarm severity level
• "alarm.status": Alarm status code
• "timeStamp.secondsPastEpoch": Timestamp seconds

Example

let value: Value = ctx.get("my:pv:name", 5.0).unwrap();

// Access different field types
let v = value.get_field_double("value").unwrap();
let severity = value.get_field_int32("alarm.severity").unwrap();

Implementations

impl Value

pub fn is_valid(&self) -> bool

Check if this value is valid

Returns false if the value is empty or uninitialized.

pub fn get_field_double(&self, field_name: &str) -> Result<f64>

Get a field value as a double

Errors

Returns an error if the field doesn’t exist or cannot be converted to a double.

pub fn get_field_int32(&self, field_name: &str) -> Result<i32>

Get a field value as an i32

Errors

Returns an error if the field doesn’t exist or cannot be converted to an i32.

pub fn get_field_string(&self, field_name: &str) -> Result<String>

Get a field value as a String

Errors

Returns an error if the field doesn’t exist or cannot be converted to a string.

pub fn get_field_enum(&self, field_name: &str) -> Result<i16>

Get a field value as a enum

Errors

Returns an error if the field doesn’t exist or cannot be converted to a enum.

pub fn get_field_double_array(&self, field_name: &str) -> Result<Vec<f64>>

Get a field value as an array of doubles

Extracts a field containing an array of double-precision floating point values. Commonly used for waveform data, measurement arrays, or multi-point setpoints.

Arguments

• field_name - The field path (e.g., “value”, “waveform.data”)

Errors

Returns an error if the field doesn’t exist or cannot be converted to an array of doubles.

Example

let value = ctx.get("waveform:double:pv", 5.0).unwrap();
let array = value.get_field_double_array("value").unwrap();
println!("Double array length: {}", array.len());
for (i, val) in array.iter().enumerate().take(5) {
    println!("  [{}] = {}", i, val);
}

pub fn get_field_int32_array(&self, field_name: &str) -> Result<Vec<i32>>

Get a field value as an array of int32

Extracts a field containing an array of 32-bit signed integers. Often used for status arrays, configuration parameters, or indexed data.

Arguments

• field_name - The field path (e.g., “value”, “status.codes”)

Errors

Returns an error if the field doesn’t exist or cannot be converted to an array of int32.

Example

let value = ctx.get("array:int32:pv", 5.0).unwrap();
let array = value.get_field_int32_array("value").unwrap();
println!("Int32 array length: {}", array.len());
for (i, val) in array.iter().enumerate().take(5) {
    println!("  [{}] = {}", i, val);
}

pub fn get_field_string_array(&self, field_name: &str) -> Result<Vec<String>>

Get a field value as an array of strings

Extracts a field containing an array of string values. Commonly used for enum choices, device names, status messages, or text lists.

Arguments

• field_name - The field path (e.g., “value.choices”, “devices.names”)

Errors

Returns an error if the field doesn’t exist or cannot be converted to an array of strings.

Example

// Get enum choices for an NTEnum PV
let value = ctx.get("enum:pv", 5.0).unwrap();
let choices = value.get_field_string_array("value.choices").unwrap();
println!("Available choices:");
for (i, choice) in choices.iter().enumerate() {
    println!("  [{}] = '{}'", i, choice);
}

Trait Implementations

impl Debug for Value

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

Formats the value using the given formatter.

impl Display for Value

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

Formats the value using the given formatter.