Struct Table 

pub struct Table { /* private fields */ }

Table is Perspective’s columnar data frame, analogous to a Pandas/Polars DataFrame or Apache Arrow, supporting append & in-place updates, removal by index, and update notifications.

A Table contains columns, each of which have a unique name, are strongly and consistently typed, and contains rows of data conforming to the column’s type. Each column in a Table must have the same number of rows, though not every row must contain data; null-values are used to indicate missing values in the dataset. The schema of a Table is immutable after creation, which means the column names and data types cannot be changed after the Table has been created. Columns cannot be added or deleted after creation either, but a View can be used to select an arbitrary set of columns from the Table.

Implementations

impl Table

pub fn get_client(&self) -> Client

Get a copy of the Client this Table came from.

pub async fn get_features(&self) -> ClientResult<Features>

Get a metadata dictionary of the perspective_server::Server’s features, which is (currently) implementation specific, but there is only one implementation.

pub fn get_index(&self) -> Option<String>

Returns the name of the index column for the table.

Examples

let options = TableInitOptions {
    index: Some("x".to_string()),
    ..default()
};
let table = client.table("x,y\n1,2\n3,4", options).await;
let index = table.get_index()

pub fn get_limit(&self) -> Option<u32>

Returns the user-specified row limit for this table.

pub fn get_name(&self) -> &str

Returns the user-specified name for this table, or the auto-generated name if a name was not specified when the table was created.

pub async fn clear(&self) -> ClientResult<()>

Removes all the rows in the Table, but preserves everything else including the schema, index, and any callbacks or registered View instances.

Calling Table::clear, like Table::update and Table::remove, will trigger an update event to any registered listeners via View::on_update.

pub async fn delete(&self, options: DeleteOptions) -> ClientResult<()>

Delete this Table and cleans up associated resources.

Tables do not stop consuming resources or processing updates when they are garbage collected in their host language - you must call this method to reclaim these.

Arguments

• options An options dictionary.
  • lazy Whether to delete this Table lazily. When false (the default), the delete will occur immediately, assuming it has no View instances registered to it (which must be deleted first, otherwise this method will throw an error). When true, the Table will only be marked for deltion once its View dependency count reaches 0.

Examples

let opts = TableInitOptions::default();
let data = TableData::Update(UpdateData::Csv("x,y\n1,2\n3,4".into()));
let table = client.table(data, opts).await?;

// ...

table.delete(DeleteOptions::default()).await?;

pub async fn columns(&self) -> ClientResult<Vec<String>>

Returns the column names of this Table in “natural” order (the ordering implied by the input format).

Examples

let columns = table.columns().await;

pub async fn size(&self) -> ClientResult<usize>

Returns the number of rows in a Table.

pub async fn schema(&self) -> ClientResult<HashMap<String, ColumnType>>

Returns a table’s [Schema], a mapping of column names to column types.

The mapping of a Table’s column names to data types is referred to as a [Schema]. Each column has a unique name and a data type, one of:

• "boolean" - A boolean type
• "date" - A timesonze-agnostic date type (month/day/year)
• "datetime" - A millisecond-precision datetime type in the UTC timezone
• "float" - A 64 bit float
• "integer" - A signed 32 bit integer (the integer type supported by JavaScript)
• "string" - A String data type (encoded internally as a dictionary)

Note that all Table columns are nullable, regardless of the data type.

pub async fn make_port(&self) -> ClientResult<i32>

Create a unique channel ID on this Table, which allows View::on_update callback calls to be associated with the Table::update which caused them.

pub async fn on_delete( &self, on_delete: Box<dyn Fn() + Send + Sync + 'static>, ) -> ClientResult<u32>

Register a callback which is called exactly once, when this Table is deleted with the Table::delete method.

Table::on_delete resolves when the subscription message is sent, not when the delete event occurs.

pub async fn remove_delete(&self, callback_id: u32) -> ClientResult<()>

Removes a listener with a given ID, as returned by a previous call to Table::on_delete.

pub async fn remove(&self, input: UpdateData) -> ClientResult<()>

Removes rows from this Table with the index column values supplied.

Arguments

• indices - A list of index column values for rows that should be removed.

Examples

table.remove(UpdateData::Csv("index\n1\n2\n3")).await?;

pub async fn replace(&self, input: UpdateData) -> ClientResult<()>

Replace all rows in this Table with the input data, coerced to this Table’s existing [Schema], notifying any derived View and View::on_update callbacks.

Calling Table::replace is an easy way to replace all the data in a Table without losing any derived View instances or View::on_update callbacks. Table::replace does not infer data types like Client::table does, rather it coerces input data to the Schema like Table::update. If you need a Table with a different Schema, you must create a new one.

Examples

let data = UpdateData::Csv("x,y\n1,2".into());
let opts = UpdateOptions::default();
table.replace(data, opts).await?;

pub async fn update( &self, input: UpdateData, options: UpdateOptions, ) -> ClientResult<()>

Updates the rows of this table and any derived View instances.

Calling Table::update will trigger the View::on_update callbacks register to derived View, and the call itself will not resolve until all derived View’s are notified.

When updating a Table with an index, Table::update supports partial updates, by omitting columns from the update data.

Arguments

• input - The input data for this Table. The schema of a Table is immutable after creation, so this method cannot be called with a schema.
• options - Options for this update step - see UpdateOptions.

Examples

let data = UpdateData::Csv("x,y\n1,2".into());
let opts = UpdateOptions::default();
table.update(data, opts).await?;

pub async fn validate_expressions( &self, expressions: Expressions, ) -> ClientResult<ExprValidationResult>

Validates the given expressions.

pub async fn view(&self, config: Option<ViewConfigUpdate>) -> ClientResult<View>

Create a new View from this table with a specified ViewConfigUpdate.

See View struct.

Examples

use crate::config::*;
let view = table
    .view(Some(ViewConfigUpdate {
        columns: Some(vec![Some("Sales".into())]),
        aggregates: Some(HashMap::from_iter(vec![("Sales".into(), "sum".into())])),
        group_by: Some(vec!["Region".into(), "Country".into()]),
        filter: Some(vec![Filter::new("Category", "in", &[
            "Furniture",
            "Technology",
        ])]),
        ..ViewConfigUpdate::default()
    }))
    .await?;

Trait Implementations

impl Clone for Table

fn clone(&self) -> Table

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl PartialEq for Table

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.