Write to a text file in a POD in CSS

1

Hi all,

If I want to write to a text file in a POD in CSS (simply write a line of string) using an http request how would I do it? I have the following patch request, but it does not work. The server is throwing me 415: UnsupportedMediaTypeHttpError error. I cannot do a put request because it will simply replace what’s already in the file. I just need to write a new line of string to the file.

final editResponse = await http.patch(
    Uri.parse(textFileUrl),
    headers: <String, String>{
      'Accept': '*/*',
      'Authorization': 'DPoP $accessToken',
      'Connection': 'keep-alive',
      'Content-Type': 'text/plain',
      'DPoP': dPopToken,
    },
    body: dataLineString,
  );

Any help in this would be much appreciated.

Thank you, Anushka

2

Unfortunately you cannot do that with a PATCH, but you can do a GET, append the string to the response body, and then PUT that.

3

Hi @Vincent, thanks for your reply. Yes, that’s a workaround. However, that wouldn’t be possible with only Write access to the file I assume?

4

Write access should be sufficient, but unfortunately Append access wouldn’t be.

5

Yes, sorry Append access wouldn’t be possible in this case. Thanks for the clarification.

6

If you store the data as rdf (eg text/turtle) you could use a n3 patch to add this entry. Here’s the specification: Solid Protocol

Here’s an example usage that adds a webId to a group (from here):

  async addCurrentUserToGroup(groupUrl: string) {
    const webId = await this.authService.getWebId();
    const n3Patch = `
@prefix solid: <http://www.w3.org/ns/solid/terms#>.
@prefix vcard: <http://www.w3.org/2006/vcard/ns#>.

_:addAccess a solid:InsertDeletePatch;
  solid:inserts { <${groupUrl}> vcard:hasMember <${webId}>. }.
`;

    await this.authService.authenticatedFetch(groupUrl, {
      method: 'PATCH',
      headers: {
        'content-type': 'text/n3',
      },
      body: n3Patch,
    });
  }
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7

It is also possible to create a new turtle file with the same N3 patch.

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