resp_stream_raw: Read a streaming body a chunk at a time

In r-lib/httr2: Perform HTTP Requests and Process the Responses

Read a streaming body a chunk at a time

Description

• resp_stream_raw() retrieves bytes (raw vectors).

• resp_stream_lines() retrieves lines of text (character vectors).

• resp_stream_sse() retrieves a single server-sent event.

• resp_stream_aws() retrieves a single event from an AWS stream (i.e. mime type 'application/vnd.amazon.eventstream“).

Use resp_stream_is_complete() to determine if there is further data waiting on the stream.

Usage

resp_stream_raw(resp, kb = 32)

resp_stream_lines(resp, lines = 1, max_size = Inf, warn = TRUE)

resp_stream_sse(resp, max_size = Inf)

resp_stream_aws(resp, max_size = Inf)

## S3 method for class 'httr2_response'
close(con, ...)

resp_stream_is_complete(resp)

Arguments

resp, con	A streaming response created by req_perform_connection().
kb	How many kilobytes (1024 bytes) of data to read.
lines	The maximum number of lines to return at once.
max_size	The maximum number of bytes to buffer; once this number of bytes has been exceeded without a line/event boundary, an error is thrown.
warn	Like readLines(): warn if the connection ends without a final EOL.
...	Not used; included for compatibility with generic.

Value

• resp_stream_raw(): a raw vector.

• resp_stream_lines(): a character vector.

• resp_stream_sse(): a list with components type, data, and id

• resp_stream_aws(): a list with components headers and body. body will be automatically parsed if the event contents a ⁠:content-type⁠ header with application/json.

resp_stream_sse() and resp_stream_aws() will return NULL to signal that the end of the stream has been reached or, if in nonblocking mode, that no event is currently available.

Examples

req <- request(example_url()) |>
  req_template("GET /stream/:n", n = 5)

con <- req |> req_perform_connection()
while (!resp_stream_is_complete(con)) {
  lines <- con |> resp_stream_lines(2)
  cat(length(lines), " lines received\n", sep = "")
}
close(con)

# You can also see what's happening by setting verbosity
con <- req |> req_perform_connection(verbosity = 2)
while (!resp_stream_is_complete(con)) {
  lines <- con |> resp_stream_lines(2)
}
close(con)

r-lib/httr2 documentation built on Jan. 11, 2025, 10:21 a.m.