Object has no method getColumnType error

问题

I have read the solution on this post but cannot seem to fit it to my issue. I am using google charts to build a line chart. x-axis being a date, y-axis being an integer.

When I run my code I get a large error message

Object {"it then lists all my JSON formatted data"} has no method 'getColumnType'.

I am getting my JSON chart data from a web service via an AJAX call. My code so far

<script type="text/javascript">

            google.load("visualization", "1", { packages: ["corechart"] });
            google.setOnLoadCallback(drawChart);


            function drawChart() {
                var jsonData = $.ajax({
                    url: "WebService.asmx/HelloWorld",
                    data: "{}",
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    async: false
                }).responseText;

                var options = {
                    title: 'Company Performance'
                };

                var chart = new google.visualization.LineChart(document.getElementById('chart_div1'));
                chart.draw(jsonData, options);
            }


    </script>

回答1:

the solution is simple....You cannot fill a google chart directly from JSON data. The JSON first needs to be formatted into a datatable. the solution looks like this:

  // Load the Visualization API and the piechart package.
          google.load('visualization', '1', { 'packages': ['annotatedtimeline'] });

          // Set a callback to run when the Google Visualization API is loaded.
          google.setOnLoadCallback(drawChart);

          function drawChart() {
              var jsonData = $.ajax({
                  url: "JSON.txt",
                  dataType: "json",
                  async: false
              }).responseText;

              // HERE IS THE FIX!!! Create our data table out of JSON data loaded from server.
              var data = new google.visualization.DataTable(jsonData);

              // Instantiate and draw our chart, passing in some options.
              var chart = new google.visualization.AnnotatedTimeLine(document.getElementById('chart_div1'));
              chart.draw(data, { width: 400, height: 240 });
          }

回答2:

I think you need to explicitly parse the JSON; $.ajax() won't do that for you in this case.

Try adding:

 jsonData = JSON.parse(jsonData);

before you build the chart.

Now, that said, I don't know what it is that's looking for a getColumnType() function; that's not going to be there on your JSON response in either string form or parsed form.

来源：https://stackoverflow.com/questions/13411545/object-has-no-method-getcolumntype-error

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javascript

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jquery

google-visualization