Tag: code

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Mapping Favicon.ico In A Golang Application

One of the most annoying issues about configuring a Go based app is correctly mapping every file to its proper path.

For instance, beginners at Go frequently declare their first handler like so:

http.HandleFunc("/", handler)

And declare a simple app.yaml, similar to the one below:

application: application_id
version: 1
runtime: go
api_version: go1

handlers:
- url: /.*
  script: _go_app

Unfortunately this will cause all requests to be routed to your Go application code, even if you have static files in your application’s root directory.

To map favicon.ico (or any static file in the app’s root directory) so AppEngine will serve it, replace the handlers section in app.yaml to properly indicate where it is and the url it maps to:

handlers:
- url: /favicon\.ico
  static_files: favicon.ico
  upload: favicon\.ico
- url: /.*
  script: _go_app
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Sending Mail With The Java Low Level API

Code example on how to send mail using the Java low level API. This code generates the appropriate From address based on your application’s ID.

MailService.Message message = new MailService.Message();
message.setSubject(subject);
message.setTextBody(body);
String application_id = SystemProperty.applicationId.get();
String sender = "donotreply@" + application_id + ".appspotmail.com";
message.setSender(sender);
MailServiceFactory.getMailService().sendToAdmins(message);
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Retrieving A Datastore Entity With A Key (or Kind Name & ID)

Short code fragment that someone might find useful: retrieve an Entity if you know what the kind and entity ID/name are.

Key key = KeyFactory.createKey("kind", "id/name");
try {
    Entity entity = DatastoreServiceFactory.getDatastoreService().get(key);
} catch (EntityNotFoundException e) {
    //The entity wasn't found. Handle this exception.
}
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Accessing and searching cells on Google Spreadsheet API

Recently I answered a question on how to access the Google Spreadsheet API. The poster was asking how to search the contents of a row/cell for a specific phrase, so I put together a quick example in Java.

The source code is below. Note that you need to replace the find_word variable with the phrase that you’re searching for, and the username and password variables with your Google username/password.

    try {
        String USERNAME = "username";
        String PASSWORD = "password";
        String find_word = "GOOG";
        find_word = find_word.toLowerCase();
        SpreadsheetService service = new SpreadsheetService(
                "GAEGROUPSEXAMPLENOPROD");
        service.setUserCredentials(USERNAME, PASSWORD);
        URL SPREADSHEET_FEED_URL = new URL(
                "https://spreadsheets.google.com/feeds/spreadsheets/private/full");
        // Make a request to the API and get all spreadsheets.
        SpreadsheetFeed feed = service.getFeed(SPREADSHEET_FEED_URL,
                SpreadsheetFeed.class);
        List<SpreadsheetEntry> spreadsheets = feed.getEntries();
        if (spreadsheets.size() == 0) {
            resp.getWriter().println(
                    "There are no spreadsheets to inspect!");
        }
        // Retrieve an iterator over all spreadsheets contained in
        // this user's Google Drive
        Iterator<SpreadsheetEntry> spreadsheet_iterator = spreadsheets
                .iterator();
        while (spreadsheet_iterator.hasNext()) {
            SpreadsheetEntry spreadsheet = spreadsheet_iterator.next();
            String spreadsheet_name = spreadsheet.getTitle().getPlainText();
            resp.getWriter().println(
                    "Currently searching spreadsheet " + spreadsheet_name);

            // Search only the first worksheet of the spreadsheet.
            WorksheetFeed worksheetFeed = service.getFeed(
                    spreadsheet.getWorksheetFeedUrl(), WorksheetFeed.class);
            List<WorksheetEntry> worksheets = worksheetFeed.getEntries();
            WorksheetEntry worksheet = worksheets.get(0);

            // Fetch the cell feed of the worksheet.
            URL cellFeedUrl = worksheet.getCellFeedUrl();
            CellFeed cellFeed = service
                    .getFeed(cellFeedUrl, CellFeed.class);

            for (CellEntry cell : cellFeed.getEntries()) {
                // Retrieve the contents of each cell.
                String cell_contents = cell.getCell().getInputValue()
                        .toLowerCase();

                // Match the word with the cell contents. Ignoring case.
                if (cell_contents.indexOf(find_word) != -1) {
                    // Found the word.
                    resp.getWriter().println(
                            "Cell with contents " + cell_contents
                                    + " matches your phrase!");
                    // Find the row
                    Integer row_index = new Integer(cell.getCell().getRow());
                    resp.getWriter().println(
                            "<b>Row " + row_index.toString() + "</b> in "
                                    + spreadsheet_name
                                    + " matches your query.");
                    String rowCollect = "";
                    // Print row data
                    URL rowCellFeedUrl = new URI(worksheet.getCellFeedUrl()
                            .toString()
                            + "?min-row="
                            + row_index
                            + "&max-row=" + row_index).toURL();
                    CellFeed rowCellFeed = service.getFeed(rowCellFeedUrl,
                            CellFeed.class);
                    // Iterate through each cell, printing its value.
                    for (CellEntry rowCell : rowCellFeed.getEntries()) {
                        // Print the cell's formula or text value
                        rowCollect += rowCell.getCell().getInputValue()
                                + "\t";
                    }
                    resp.getWriter().println(
                            "<b>Row Data: </b>" + rowCollect);
                }
            }// end for looping through cells
        }// end while looping through spreadsheets

    } catch (Exception e) {
        resp.getWriter().println("Exception: " + e.getMessage());
    }

Also, don’t put this example into production use until you switch out the authentication service to OAuth (this example uses ClientLogin to authenticate).