International characters in filenames

[Artem K.]

Hi,

I am migrating to V2 of REST API and I am having problems with endpoints that require passing arguments using "Dropbox-API-Arg" header (for example, https://content.dropboxapi.com/2/files/download).

The problem is I am not being able to pass filenames containing international characters.

For example, I have a file "моя запись.txt" saved in my folder, with path "/моя запись.txt"

When I try to simply pass this string in the header, I get an error from ajax:

SyntaxError: Failed to execute 'setRequestHeader' on 'XMLHttpRequest': '{"path":"/моя запись.txt"}' is not a valid HTTP header field value.

In V1 of API I simply encoded every path using encodeURIComponent function. In that case the path "/моя запись.txt" would become "%2F%D0%BC%D0%BE%D1%8F%20%D0%B7%D0%B0%D0%BF%D0%B8%D1%81%D1%8C.txt" and that worked for V1.

However, when I try the same with the V2, I get the following error from API:

Error in call to API function "files/download": HTTP header "Dropbox-API-Arg": path: '%2F%D0%BC%D0%BE%D1%8F%20%D0%B7%D0%B0%D0%BF%D0%B8%D1%81%D1%8C.txt' did not match pattern...

I tried to bypass this validation by keeping the slash and encoding only the file name itself. In this case the filepath becomes "/%D0%BC%D0%BE%D1%8F%20%D0%B7%D0%B0%D0%BF%D0%B8%D1%81%D1%8C.txt". This seems to be recognized as a valid path, but I get a new error:

"path/not_found/"

How do I correctly pass that path "/моя запись.txt" to the API endpoint?

Thank you,

Artem

[Artem K.]

In the end I was able to pass such a file name using URL parameter arg, encoded using encodeURIComponent function. So it seems that "Dropbox-API-Arg" header is not really usable in multi-language scenarios.

[Artem K.]

API explorer seems to encode the same file path as "/\u043c\u043e\u044f \u0437\u0430\u043f\u0438\u0441\u044c.txt". OK, I just probably need to find the way to do this conversion in JavaScript.

[Greg-DB]

Hi Artem, as you saw in the API Explorer, for these calls with the parameters in the header, you need to escape these characters. That is, when you use the “Dropbox-API-Arg” header, you need to make it “HTTP header safe”. This means using JSON-style “\uXXXX” escape codes for the character 0x7F and all non-ASCII characters.

Some, but not all, languages/libraries do this for you. For example, for JavaScript, to do this yourself you could do something like this:

var charsToEncode = /[\u007f-\uffff]/g;

function http_header_safe_json(v) {
 return JSON.stringify(v).replace(charsToEncode,
 function(c) {
 return '\\u' + ('000' + c.charCodeAt(0).toString(16)).slice(-4);
 }
 );
}

and then something like:

'Dropbox-API-Arg': http_header_safe_json({ path: dropboxFilePath })

[Artem K.]

Thank you Gregory,

Ideally I would prefer to use some standard function instead of implementing encoding myself, but your example looks simple/robust enough.

[jianwen]

There is Chinese in path like："/blackdog/中文prd.docx“，i see the api explore send Dropbox-API-Arg as follow:

Dropbox-API-Arg:{"path":"/blackdog/\u4e2d\u6587prd.docx"}

I am using java to implement http,my Dropbox-API-Arg as follow:

"Dropbox-API-Arg:  {"path":"/blackdog/\\u4E2D\\u6587prd.docx"}"

In java \\ standard for one \,and dropbox response as follow:

path/not_found/.

How could i resolve the issue?

[jianwen]

I try the url arg parameter as follow(url encoded):

"POST /2/files/get_preview?arg=%257B%2522path%2522%253A%2522%252Fblackdog%252F%25E4%25B8%25AD%25E6%2596%2587PRD.docx%2522%257D HTTP/1.1[\r][\n]"

not work neither,get error as follow

 "Error in call to API function "files/get_preview": URL parameter "arg": could not decode input as JSON[\r][\n]"

[Greg-DB]

This may depend on your setup, but are you sure you need the double '/'? Have you tried it without it? i.e.,

"Dropbox-API-Arg: {"path":"/blackdog/\u4e2d\u6587prd.docx"}"

In any case, we recommend either using the official Dropbox Java SDK, or having a library do the encoding for you. E.g., for Java, using Jackson, it would look like:

JsonFactory f = ...
JsonGenerator g = f.createGenerator(...);
g.setHighestNonEscapedChar(0x7E);

[jianwen]

Actually i use Jackson format json as follow:

        String path = "/blackdog/中文PRD.docx";
        path = StringEscapeUtils.escapeJava(path);
        path_req.setPath(path);
        String header_json = JsonUtils.writeValue(path_req);
        LoggerUtils.logInfo(this.getClass(), header_json);

In java double / standards /,so following code 

"Dropbox-API-Arg: {"path":"/blackdog/\u4e2d\u6587prd.docx"}"

is correct in Java.

[jianwen]

I debuged Dropbox java sdk,and the header Dropbox-API-Arg value is the same as mine

 "Dropbox-API-Arg:  {"path":"/blackdog/\\u4E2D\\u6587prd.docx"}[\r][\n]"

but i got 409 path/not_found/..,dropbox sdk get right response,i don not why.