Ability to return html string directly and avoid opening browser locally

[mskyttner]

Thanks for a great extension, very useful!

I would love the ability to get the html string directly.

The steps for writing the html string to disk and launching browser are difficult to skip currently.

Rationale: When using the extension on headless servers it may not have a browser available, so a way to avoid the launching of the browser would be great. Also ability to write the html string directly for example to stdout via COPY (...) TO '/dev/stdout'; allows for usage with pipes.

Current workaround, which picks up the returned path to the generated file from the return value and reads the html back and stores the chart it in a table:

load miniplot;

set variable my_chart = (
    select regexp_extract(bar_chart(
        ['Q1', 'Q2', 'Q3', 'Q4'],
        [100.0, 150.0, 200.0, 180.0],
        'Quarterly Sales'
    ) , 'opened: (.*?mp/.*?)$', 1)
);

create or replace table my_charts as (
    from read_text(getvariable('my_chart')) 
    select 
        title: 'Quarterly Sales',
        html: content,
        file: getvariable('my_chart'),
);

from my_charts select html limit 1;

[nkwork9999]

Thank you for feedback and sharing ideas,And impressive!
I think two improvement.

1:making each function

SELECT bar_chart(x, y, title);
→ "Chart opened: /tmp/duckdb_chart_xxx.html"

SELECT bar_chart_file(x, y, title);
→ "/tmp/duckdb_chart_xxx.html"

• Writes HTML content to a file
• Returns the file path
• Does NOT open browser

2:Use a single function with an output parameter:
SELECT bar_chart(['Q1','Q2'], [100,150], 'Sales', output := 'browser');
SELECT bar_chart(['Q1','Q2'], [100,150], 'Sales', output := 'file');

• Write HTML content to a file
• Return the file path
• 'browser' mode: also opens browser
• 'file' mode: no browser launch

I'm hesitant to implement an _html() variant that returns raw HTML strings directly due to security concerns (memory exhaustion risks).

Looking forward to your thoughts.

[nkwork9999]

Update: File Output Control Implemented in v0.0.3

Thank you for your patience! I've implemented a solution that addresses your needs.

-- Opens in browser (default behavior)
SELECT bar_chart(['Q1','Q2','Q3','Q4'], [100,150,200,180], 'Sales');

-- Saves to /tmp/ without opening browser
SELECT bar_chart(['Q1','Q2','Q3','Q4'], [100,150,200,180], 'Sales', 'tmp');

-- Saves to custom path without opening browser  
SELECT bar_chart(['Q1','Q2','Q3','Q4'], [100,150,200,180], 'Sales', '/path/to/output.html');

Return Values

• No path parameter: Returns "Chart opened: /tmp/duckdb_chart_xxx.html" and opens browser
• 'tmp' parameter: Returns /tmp/duckdb_chart_xxx.html (path only, no browser)
• Custom path: Returns the specified path (no browser)

Your Workaround - Simplified

Piping to stdout

COPY (
    WITH chart AS (
        SELECT bar_chart(['Q1','Q2'], [100,150], 'Sales', 'tmp') AS path
    )
    SELECT content FROM read_text((SELECT path FROM chart))
) TO '/dev/stdout';

Availability

This feature is included in v0.0.3 and will be available once the PR to the official DuckDB Community Extensions repository is merged.