數據未從PHP JSON顯示在Chart JS中

Question

嗨，我正在嘗試使用Chartjs顯示動態折線圖，並使用PHP以JSON格式從SQL中提取數據。 數據已成功選擇，但不能僅顯示空白圖表，希望對您有所幫助。

$(document).ready(function() {
  var dataPointsA = []
  var dataPointsB = []

  $.ajax({
    type: 'GET',
    url: 'data.php',
    dataType: 'json',
    success: function(field) {

      for (var i = 0; i < field.length; i++) {
        dataPointsA.push({
          x: field[i].datetime,
          y: field[i].roomtemp
        });
        dataPointsB.push({
          x: field[i].datetime,
          y: field[i].tanktemp
        });
      }
console.log(field);
      var chartdata = {
        title: {
          text: "Fish Tank Monitor"
        },

        data: [{
          type: "line",
          name: "line1",
          dataPoints: dataPointsA
        }, {
          type: "line",
          name: "line2",
          dataPoints: dataPointsB
        }, ]
      };
console.log(chartdata);

      var ctx = mycanvas.getContext('2d');

      var barGraph = new Chart(ctx, {
                type: 'line',
                data: chartdata,
                backgroundColor: 'rgba(0, 119, 204, 0.3)'
            });
    }
  });
});

JSON范例

[{"datetime":"2018-07-28 22:33:00.000","roomtemp":26.9,"tanktemp":28.4},{"datetime":"2018-07-28 22:32:00.000","roomtemp":26.9,"tanktemp":28.4},{"datetime":"2018-07-28 22:31:00.000","roomtemp":26.9,"tanktemp":28.4},{"datetime":"2018-07-28 22:30:00.000","roomtemp":26.9,"tanktemp":28.4},{"datetime":"2018-07-28 22:29:00.000","roomtemp":26.9,"tanktemp":28.4},{"datetime":"2018-07-28 22:28:00.000","roomtemp":26.9,"tanktemp":28.4},{"datetime":"2018-07-28 22:27:00.000","roomtemp":26.9,"tanktemp":28.4},{"datetime":"2018-07-28 22:26:00.000","roomtemp":26.8,"tanktemp":28.4},{"datetime":"2018-07-28 22:25:00.000","roomtemp":26.9,"tanktemp":28.4},{"datetime":"2018-07-28 22:24:00.000","roomtemp":26.9,"tanktemp":28.4}]

Answer 1

我認為這是由於日期時間格式不正確而引起的。 您使用的datetime鍵充當字符串。 我認為您需要應用一個日期和時間過濾器