From d2a3f2cedd7c00d0933222aed9c06b3149aa4db4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= Date: Wed, 4 Apr 2018 13:13:37 +0200 Subject: Cowboy 2.3.0 --- .../2.3/manual/cowboy_req.read_part/index.html | 301 +++++++++++++++++++++ 1 file changed, 301 insertions(+) create mode 100644 docs/en/cowboy/2.3/manual/cowboy_req.read_part/index.html (limited to 'docs/en/cowboy/2.3/manual/cowboy_req.read_part/index.html') diff --git a/docs/en/cowboy/2.3/manual/cowboy_req.read_part/index.html b/docs/en/cowboy/2.3/manual/cowboy_req.read_part/index.html new file mode 100644 index 00000000..0b0cf91e --- /dev/null +++ b/docs/en/cowboy/2.3/manual/cowboy_req.read_part/index.html @@ -0,0 +1,301 @@ + + + + + + + + + + + + Nine Nines: cowboy_req:read_part(3) + + + + + + + + + + + + + + +
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cowboy_req:read_part(3)

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+

Name

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+

cowboy_req:read_part - Read the next multipart headers

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+

Description

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+
read_part(Req :: cowboy_req:req())
+    -> read_part(Req, #{})
+
+read_part(Req :: cowboy_req:req(), Opts)
+    -> {ok, Headers, Req} | {done, Req}
+
+Opts    :: cowboy_req:read_body_opts()
+Headers :: #{binary() => binary()}
+

Read the next part of a multipart body.

+

This function reads the request body and parses it as +multipart. Each parts of a multipart representation have +their own headers and body. This function parses and returns +headers. Examples of multipart media types are +multipart/form-data and multipart/byteranges.

+

Cowboy will skip any data remaining until the beginning of +the next part. This includes the preamble to the multipart +message but also the body of a previous part if it hasn’t +been read. Both are skipped automatically when calling this +function.

+

Cowboy will read the body before parsing in chunks of size +up to 64KB, with a period of 5 seconds. This is tailored for +reading part headers and might not be the most efficient for +skipping the previous part’s body.

+

The headers returned are MIME headers, NOT HTTP headers. +They can be parsed using the functions from the cow_multipart +module. In addition, the cow_multipart:form_data/1 function +can be used to quickly extract information from multipart/form-data +representations.

+

Once a part has been read, it can not be read again.

+

Once the body has been read, Cowboy sets the content-length +header if it was not previously provided.

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Arguments

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+Req +
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+The Req object. +

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+Opts +
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+

+A map of body reading options. Please refer to +cowboy_req:read_body(3) +for details about each option. +

+

This function defaults the length to 64KB and the period +to 5 seconds.

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Return value

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An ok tuple is returned containing the next part’s headers +as a map.

+

A done tuple is returned if there are no more parts to read.

+

The Req object returned in the tuple must be used for that point +onward. It contains a more up to date representation of the request. +For example it may have an added content-length header once the +body has been read.

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Changelog

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  • +

    +2.0: Function introduced. Replaces part/1,2. +

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Examples

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+
Read all parts
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+
acc_multipart(Req0, Acc) ->
+    case cowboy_req:read_part(Req0) of
+        {ok, Headers, Req1} ->
+            {ok, Body, Req} = stream_body(Req1, <<>>),
+            acc_multipart(Req, [{Headers, Body}|Acc]);
+        {done, Req} ->
+            {lists:reverse(Acc), Req}
+    end.
+
+stream_body(Req0, Acc) ->
+    case cowboy_req:read_part_body(Req0) of
+        {more, Data, Req} ->
+            stream_body(Req, << Acc/binary, Data/binary >>);
+        {ok, Data, Req} ->
+            {ok, << Acc/binary, Data/binary >>, Req}
+    end.
+
+
Read all part headers, skipping bodies
+
+
skip_body_multipart(Req0, Acc) ->
+    case cowboy_req:read_part(Req0) of
+        {ok, Headers, Req} ->
+            skip_body_multipart(Req, [Headers|Acc]);
+        {done, Req} ->
+            {lists:reverse(Acc), Req}
+    end.
+
+
Read a part header in larger chunks
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+
{ok, Headers, Req} = cowboy_req:read_part(Req0, #{length => 1000000}).
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+

See also

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+

cowboy_req(3), +cowboy_req:has_body(3), +cowboy_req:body_length(3), +cowboy_req:read_body(3), +cowboy_req:read_urlencoded_body(3), +cowboy_req:read_part_body(3)

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+ + + + + +
+ +
+ + +

+ Cowboy + 2.3 + Function Reference + +

+ + + +

Navigation

+ +

Version select

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