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I want to display a Google Chart (Line Chart) on .jsp page of my Spring MVC application. The data is retrieved from a MySQL database, so I need to convert the YYYY-MM-DD HH:MM:SS format into Javascript's Date.

The database is created by Hibernate. The Reading entity has a time field of type java.sql.Timestamp, which is stored as DATETIME in the database.

The results is an Iterable<Reading> object passed to the .jsp via controller. It is passed correctly (I am displaying the data as a table, too).

I'm trying to use the solution proposed here, but it does not work.

Here's the code I'm trying to populate the chart with:

<c:forEach items="${results}" var="reading">
    var t = "${reading.time}".split(/[- :]/);
    var d = new Date(t[0], t[1]-1, t[2], t[3], t[4], t[5]);
    data.addRow([d,${reading.temperature}]);
</c:forEach>

The chart is not displaying.

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1 Answers1

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Facts:

Put together:

<c:forEach items="${results}" var="reading">
    <fmt:formatDate var="time" value="${reading.time}" pattern="yyyy-MM-dd'T'HH:mm:ss" timeZone="UTC" />
    var d = new Date("${time}");
    // ...
</c:forEach>

Alternatively, just convert results to JSON using a decent JSON formatter in the controller and print it as if it's a JS variable like so var data = ${data};. See also a.o. How to access array of user defined objects within <script> in JSP?

Unrelated to the concrete problem: make sure your model is of java.util.Date type. You shouldn't have java.sql.* typed properties in your model. If you're using plain JDBC, just upcast ResultSet#getTimestamp() to java.util.Date directly. See also a.o. Handling MySQL datetimes and timestamps in Java.

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  • Thank you for the hints and the answer. However, the above code does not work. I think I will try the JSON solution. – RK1 Oct 20 '15 at 18:10
  • The chart is not displaying. I am using `data.addRow([d, ${reading.temperature}]);`. How can I debug this? I don't know Javascript at all, unfortunately. – RK1 Oct 20 '15 at 18:30
  • Just look in generated HTML output if JSTL has done its job the expected way. If it did, then the problem is beyond JSP/JSTL and you'd have had exactly the same problem when using a hardcoded JS variable. – BalusC Oct 20 '15 at 18:32
  • I am displaying the contents of `results` in a table and just noticed that time time got a `.0` at the end. Maybe that's the case, or should I change the pattern in `formatDate`? – RK1 Oct 20 '15 at 18:33
  • Check the generated HTML output instead of guessing based on the browser's interpretation and presentation. Rightclick page, *View Source*. – BalusC Oct 20 '15 at 18:33
  • In the HTML output, I see: `var d = new Date("2015-10-14T21:05:22.0"); data.addRow([d,5.0]);` – RK1 Oct 20 '15 at 18:35
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    Then JSTL has properly done its job as to printing/formatting the JS date variable and your new problem is beyond the scope of the question. Just press [Ask Question] button in right top if you can't figure out it. – BalusC Oct 20 '15 at 18:36