Struct Fields 

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

What a form was filled in with.

Every answer arrives as text, because that is what a control on a page produces: a number box hands back the digits that were typed, and an empty box hands back nothing at all. So a field is read through the reader that suits it, and a field holding something that field cannot be is a 400 naming it rather than a panic or a silent zero.

Implementations

impl Fields

pub fn get(&self, key: &str) -> Option<&str>

The answer as it was typed, or nothing where the form did not carry the field at all.

pub fn text(&self, key: &str) -> &str

The answer as text, trimmed. A field nobody filled in is empty rather than absent, since a form that was saved answered every field it had.

Examples found in repository

examples/library/main.rs (line 945)

    fn lend(fields: &Fields, args: &ViewArgs, ctx: &Context) -> Result<String, ApiError> {
        let title = args.get_or("title", "");
        let borrower = fields.text("borrower");
        let days = fields.integer("days")?;
        let from = fields.date("from")?;
        let condition = fields.text("condition").to_lowercase();

        if borrower.is_empty() {
            return Err(ApiError::bad_request("a loan needs a borrower"));
        }
        if days < 1 {
            return Err(ApiError::bad_request("a loan is at least one day long"));
        }
        let start = days_from_civil(from).ok_or_else(|| {
            ApiError::bad_request(format!("{from} is not a date in the calendar"))
        })?;
        let due = civil_from_days(start + days);

        let mut books: Vec<Book> = ctx.rows(BOOKS_FILE)?;
        let book = books
            .iter_mut()
            .find(|b| b.title == title)
            .ok_or_else(|| ApiError::bad_request(format!("no book is called \"{title}\"")))?;
        if book.lent.unwrap_or(false) {
            return Err(ApiError::bad_request(format!("\"{title}\" is already out")));
        }
        book.lent = Some(true);
        book.due = due.clone();
        book.notes = format!("Lent to {borrower} on {from}, {condition}.");

        let problems = Books.validate(&books, ctx)?;
        if let Some(first) = problems.first() {
            return Err(ApiError::bad_request(format!(
                "the loan would leave row {} in a state the table refuses: {}",
                first.line, first.message
            )));
        }

        let text = Books
            .serialize(&books)
            .map_err(|e| ApiError::server(format!("could not serialize {BOOKS_FILE}: {e}")))?;
        ctx.write(BOOKS_FILE, &text)?;

        Ok(format!("\"{title}\" is out to {borrower} until {due}."))
    }

pub fn integer(&self, key: &str) -> Result<i64, ApiError>

The answer as a whole number.

Examples found in repository

examples/library/main.rs (line 946)

    fn lend(fields: &Fields, args: &ViewArgs, ctx: &Context) -> Result<String, ApiError> {
        let title = args.get_or("title", "");
        let borrower = fields.text("borrower");
        let days = fields.integer("days")?;
        let from = fields.date("from")?;
        let condition = fields.text("condition").to_lowercase();

        if borrower.is_empty() {
            return Err(ApiError::bad_request("a loan needs a borrower"));
        }
        if days < 1 {
            return Err(ApiError::bad_request("a loan is at least one day long"));
        }
        let start = days_from_civil(from).ok_or_else(|| {
            ApiError::bad_request(format!("{from} is not a date in the calendar"))
        })?;
        let due = civil_from_days(start + days);

        let mut books: Vec<Book> = ctx.rows(BOOKS_FILE)?;
        let book = books
            .iter_mut()
            .find(|b| b.title == title)
            .ok_or_else(|| ApiError::bad_request(format!("no book is called \"{title}\"")))?;
        if book.lent.unwrap_or(false) {
            return Err(ApiError::bad_request(format!("\"{title}\" is already out")));
        }
        book.lent = Some(true);
        book.due = due.clone();
        book.notes = format!("Lent to {borrower} on {from}, {condition}.");

        let problems = Books.validate(&books, ctx)?;
        if let Some(first) = problems.first() {
            return Err(ApiError::bad_request(format!(
                "the loan would leave row {} in a state the table refuses: {}",
                first.line, first.message
            )));
        }

        let text = Books
            .serialize(&books)
            .map_err(|e| ApiError::server(format!("could not serialize {BOOKS_FILE}: {e}")))?;
        ctx.write(BOOKS_FILE, &text)?;

        Ok(format!("\"{title}\" is out to {borrower} until {due}."))
    }

pub fn number(&self, key: &str) -> Result<f64, ApiError>

The answer as a number, whole or not.

inf and NaN parse as floats and are refused with the rest: a row holding one serialises to null, which would put a wrong value in a file rather than say the answer was no good.

pub fn date(&self, key: &str) -> Result<&str, ApiError>

The answer as a YYYY-MM-DD date.

The shape is checked and the ranges with it, so nothing beyond a real month and a plausible day gets through; which days a month actually has is a calendar question, and the repository writing the date is what holds a calendar.

Examples found in repository

examples/library/main.rs (line 947)

    fn lend(fields: &Fields, args: &ViewArgs, ctx: &Context) -> Result<String, ApiError> {
        let title = args.get_or("title", "");
        let borrower = fields.text("borrower");
        let days = fields.integer("days")?;
        let from = fields.date("from")?;
        let condition = fields.text("condition").to_lowercase();

        if borrower.is_empty() {
            return Err(ApiError::bad_request("a loan needs a borrower"));
        }
        if days < 1 {
            return Err(ApiError::bad_request("a loan is at least one day long"));
        }
        let start = days_from_civil(from).ok_or_else(|| {
            ApiError::bad_request(format!("{from} is not a date in the calendar"))
        })?;
        let due = civil_from_days(start + days);

        let mut books: Vec<Book> = ctx.rows(BOOKS_FILE)?;
        let book = books
            .iter_mut()
            .find(|b| b.title == title)
            .ok_or_else(|| ApiError::bad_request(format!("no book is called \"{title}\"")))?;
        if book.lent.unwrap_or(false) {
            return Err(ApiError::bad_request(format!("\"{title}\" is already out")));
        }
        book.lent = Some(true);
        book.due = due.clone();
        book.notes = format!("Lent to {borrower} on {from}, {condition}.");

        let problems = Books.validate(&books, ctx)?;
        if let Some(first) = problems.first() {
            return Err(ApiError::bad_request(format!(
                "the loan would leave row {} in a state the table refuses: {}",
                first.line, first.message
            )));
        }

        let text = Books
            .serialize(&books)
            .map_err(|e| ApiError::server(format!("could not serialize {BOOKS_FILE}: {e}")))?;
        ctx.write(BOOKS_FILE, &text)?;

        Ok(format!("\"{title}\" is out to {borrower} until {due}."))
    }

pub fn iter(&self) -> impl Iterator<Item = (&str, &str)>

Every key and answer, in order.

Trait Implementations

impl Clone for Fields

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 Fields

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

Formats the value using the given formatter.

impl Default for Fields

fn default() -> Self

Returns the “default value” for a type.