I'm always hesitant not to use start and end dates, due to potential performance problems, so this is the PROTOTYPE code I'm using:
//1. Initializing variables
let startDate = parseDate("2024-05-28 23:06:34", "yyyy-MM-dd HH:mm:ss");
let endDate = parseDate("2024-05-29 00:19:30", "yyyy-MM-dd HH:mm:ss");
let propertyName = "myProperty";
let maxItems = 5;
//2. Main Query service. This one does not return the value we need (by design)
result = me.QueryNumberPropertyHistory({
maxItems: maxItems /* NUMBER {"defaultValue":500} */ ,
propertyName: propertyName /* STRING */ ,
startDate: startDate /* DATETIME */ ,
endDate: endDate /* DATETIME */ ,
quality: undefined /* STRING */ ,
oldestFirst: true /* BOOLEAN */ ,
query: undefined /* QUERY */
});
//3. Add the last known historical value to the display dataset
//3.1. we verify if we have the last logged value in the result
//most of the time it won't be, as the user can't select a start date that is exactly the date when a property was logged
if (result.getRow(0).timestamp != startDate) {
//3.2. Querying backwards the historical dataset, starting from 3 days ago until the start date, sorting with the newest value first
let value = me.QueryNumberPropertyHistory({
maxItems: maxItems /* NUMBER {"defaultValue":500} */ ,
propertyName: propertyName /* STRING */ ,
startDate: dateAddDays(startDate, -3) /* DATETIME */ ,
endDate: startDate /* DATETIME */ ,
quality: undefined /* STRING */ ,
oldestFirst: false /* BOOLEAN */ ,
query: undefined /* QUERY */
}).getRow(0).value;
//3.3. We add this value to the return dataset
//We're not using the original timestamp because we don't want to (possibly) modify the way the chart displays
//in case the latest value was 2 days back
result.AddRow({
value: value,
timestamp: startDate
});
}
//3.4. One last sort based on timestamp, because we added the row at the end of the dataset
let sort = {
name: "timestamp",
ascending: true
};
result.Sort(sort);
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