Struct DataFilter 

pub struct DataFilter {

    pub absolute_path: PathBuf,
    pub table_name: String,
    pub csv_delimiter: String,
    pub read_data_from_file: bool,
    pub schema: Arc<Schema>,
    pub infer_schema_rows: usize,
    pub exclude_null_cols: bool,
    pub null_values: String,
    pub force_string_patterns: Option<String>,
    pub apply_sql: bool,
    pub query: String,
    pub add_row_index: bool,
    pub index_column_name: String,
    pub index_column_offset: u32,
    pub normalize: bool,
    pub normalize_regex: String,
    pub drop: bool,
    pub drop_regex: String,
}

Holds configuration parameters related to loading and querying data.

This struct focuses on settings that define how data is initially read from a file and transformed via SQL queries or basic processing like null column removal.

Instances are created from Arguments, updated by the UI in render_query, and passed to DataFrameContainer::load_data. Changes here typically trigger a data reload/requery.

Fields

absolute_path: PathBuf

The canonical, absolute path to the data file.

table_name: String

The name assigned to the loaded DataFrame for use in SQL queries.

csv_delimiter: String

The character used to separate columns in a CSV file.

read_data_from_file: bool

Read data from file

schema: Arc<Schema>

The schema (column names and data types) of the most recently loaded DataFrame. Used by sql_commands for generating relevant examples.

infer_schema_rows: usize

Maximum rows to scan for schema inference (CSV, JSON, NDJson).

exclude_null_cols: bool

Flag to control removal of all-null columns after loading/querying.

null_values: String

Comma-separated string of values to interpret as nulls during CSV parsing.

force_string_patterns: Option<String>

Regex patterns matching columns to force read as String type.

List of column names to force reading as String, overriding inference. Useful for columns with large IDs/keys that look numeric.

apply_sql: bool

Flag indicating if the query should be executed during the next load_data. Set by render_query if relevant UI fields change or the Apply button is clicked.

query: String

The SQL query string entered by the user.

add_row_index: bool

Flag indicating if a row index column should be added.

index_column_name: String

The desired name for the row index column (will be checked for uniqueness later).

index_column_offset: u32

The starting value for the row index column (e.g., 0 or 1).

normalize: bool

Flag indicating whether string columns will be normalized.

normalize_regex: String

Regex pattern to select string columns.

drop: bool

drop_regex: String

Implementations

impl DataFilter

pub fn new(args: &Arguments) -> PolarsViewResult<Self>

Creates a new DataFilter instance configured from command-line Arguments. This is typically called once at application startup in main.rs.

Arguments

• args: Parsed command-line arguments (crate::Arguments).

Returns

A PolarsViewResult containing the configured DataFilter or an error (e.g., if the path cannot be canonicalized).

pub fn set_path(&mut self, path: &Path) -> PolarsViewResult<()>

Sets the data source path, canonicalizing it.

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

Gets the file extension from absolute_path in lowercase.

pub fn get_row_index(&self, schema: &Schema) -> PolarsResult<Option<RowIndex>>

Determines the configuration for an optional row index column by resolving a unique name against the provided schema.

If self.add_row_index is true, this method finds a unique name based on self.index_column_name and the provided schema, returning a Some(RowIndex). If the name resolution fails, it returns the specific PolarsError. If self.add_row_index is false, it returns Ok(None).

Arguments

• schema: The schema against which the index column name should be checked for uniqueness. This should be the schema of the DataFrame before adding the index column.

Returns

PolarsResult<Option<RowIndex>>: Ok(Some) if config is resolved, Ok(None) if disabled, Err if resolution fails.

pub async fn get_df_and_extension( &mut self, ) -> PolarsViewResult<(DataFrame, FileExtension)>

Determines the FileExtension and orchestrates loading the DataFrame using the appropriate Polars reader. This method centralizes the file-type-specific loading logic. Called by DataFrameContainer::load_data.

Important: It mutates self by potentially updating csv_delimiter if automatic detection during read_csv_data finds a different working delimiter than initially configured.

Returns

A PolarsViewResult containing a tuple: (DataFrame, FileExtension) on success, or a PolarsViewError (e.g., FileType, CsvParsing) on failure.

pub fn parse_null_values(&self) -> Vec<&str>

Parses the comma-separated null_values string into a Vec<&str>, removing surrounding double quotes if present.

Logic:

1. Splits the input string (self.null_values) by commas.
2. Iterates through each resulting substring (s).
3. For each substring: a. Trims leading and trailing whitespace. b. Checks if the trimmed string has at least 2 characters AND starts with " AND ends with ". c. If true, returns a slice (&str) representing the content between the quotes. Example: "\"\"" becomes "", " N/A " becomes "N/A", " " " becomes " ". d. If false (no surrounding quotes), returns a slice (&str) of the trimmed string itself. Example: <N/D> remains <N/D>, NA becomes NA.
4. Collects all the resulting string slices into a Vec<&str>.

Example Input: "\"\", \" \", <N/D>, NA " Example Output: vec!["", " ", "<N/D>", "NA"]

pub fn render_query(&mut self, ui: &mut Ui) -> Option<DataFilter>

Renders the UI widgets for configuring data filters within the “Query” collapsing header. This function is called by layout.rs::render_side_panel.

Crucially, it takes &mut self. Widgets modify self directly. It compares the state of self before and after rendering the widgets. If any change occurred (user typed in a field, clicked a checkbox), it returns Some(self.clone()) containing the modified state. Otherwise, it returns None.

The layout.rs code uses this return value:

• If Some(new_filters), it triggers an asynchronous DataFrameContainer::load_data call.
• If None, no user change was detected in this frame, so no action is taken.

It also sets self.apply_sql = true if any changes are detected, ensuring the SQL query is re-applied upon reload.

Arguments

• ui: The egui::Ui context for drawing the widgets.

Returns

• Some(DataFilter): If any filter setting was changed by the user in this frame.
• None: If no changes were detected.

Trait Implementations

impl Clone for DataFilter

fn clone(&self) -> DataFilter

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for DataFilter

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

Formats the value using the given formatter.

impl Default for DataFilter

fn default() -> Self

Creates default DataFilter with sensible initial values.

impl PartialEq for DataFilter

fn eq(&self, other: &DataFilter) -> 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.

impl StructuralPartialEq for DataFilter