Struct ExtractError 

pub struct ExtractError(/* private fields */);

Available on crate feature query only.

Why extraction failed, where, and what it was reading.

Its Display gives the field path, the selector and the source, then the reason:

Product.title ("h1"): no element matches
Product.price (".price" @data-value): cannot parse "$5" as f64: invalid float literal
Product.price (".price" @data-value): <span> has no "data-value" attribute
Product.sku (@data-sku): a document has no attributes; give the field a selector or extract from an element
Cents.cents (".price"): cannot convert "$x" with parse_cents: no digits
Typo.title ("h1:hover"): invalid selector: unsupported pseudo-class ':hover' at byte 2
Card: extract_all needs a selector on the type: #[html(select = "…")]

The path names the type and field. Nested structs prefix the outer field (Product.seller.name), Vec items add their index (Product.reviews[1].rating) and so do Dom::extract_all items (Product[1].title). The parentheses hold the selector and the source (@attr, html, outer_html, markdown); a text or nested field shows only its selector, and one with neither has no parentheses. Values are quoted and escaped like {:?}, cut short after 60 characters.

It is one pointer wide (the details are boxed), so Result<T, ExtractError> costs little on the success path.

Implementations

impl ExtractError

pub fn new(kind: ExtractErrorKind) -> Self

A new error of kind, without a path, selector or source yet.

pub fn kind(&self) -> &ExtractErrorKind

What went wrong.

pub fn path(&self) -> String

Where: the type and field path, like Product.reviews[2].rating (empty for a value read directly, like dom.extract::<f64>()).

use domq::{ExtractError, ExtractErrorKind};

let err = ExtractError::new(ExtractErrorKind::NoMatch)
    .in_field("Review", "rating")
    .at_index(2)
    .in_field("Product", "reviews");
assert_eq!(err.path(), "Product.reviews[2].rating");

pub fn selector(&self) -> Option<&str>

The selector being matched when it failed (the innermost one).

pub fn value_source(&self) -> Option<&ValueSource>

The value being read when it failed, if it got that far.

pub fn with_selector(self, selector: &str) -> Self

Record the selector being matched, unless the error already names one (the innermost selector is the most specific).

pub fn with_source(self, source: ValueSource) -> Self

Record the value being read, unless the error already names one.

pub fn in_field(self, type_name: &'static str, field: &'static str) -> Self

Put the error inside field field of type type_name: the path Seller.name becomes Product.seller.name after .in_field("Product", "seller").

pub fn at_index(self, index: usize) -> Self

Put the error inside item index of a list: Review.rating becomes Review[2].rating, and after in_field Product.reviews[2].rating.

Trait Implementations

impl Clone for ExtractError

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ExtractError

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

Formats the value using the given formatter.

impl Display for ExtractError

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

Formats the value using the given formatter.

impl Eq for ExtractError

impl Error for ExtractError

Available on crate feature std only.

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for ExtractError

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for ExtractError