calculate Max and min value from QueryPropertyHistory

There are two ways ho to achieve this non if which with standard query service.

You can create one service which queries your source (pre-defined or dynamic) does the calculation and returns back the result.

Or you can tether up two services together so it is easier to use in mashups. (my favorite )

Start with creating Thing let say MinMaxCalculator

create a service in that thing called calculate

create three input parameters:

propertyName1:"string"

propertyName2:"string"

values:"infotable"

snippet:

var valuesRowCount = values.getRowCount();

var min = 1000000; // some ridiculously high min

var max = -1000000; // some ridiculously low max

var count = 0;

for (var i=0; i < valuesRowCount; i++)

{

    if (!y || !z){continue;}    // skip empty cells - that does happen with value streams

     min = (values.rows[propertyName2] < min) ? 'values.rows[propertyName1]' : 'min';   

     max = (values.rows[propertyName2] > max) ? 'values.rows[propertyName2]' : 'max';

     count++; // that is not always the same as valuesRowCount

}

// output form schema

var params = {

  infoTableName: "tempInfoTable" /* STRING */

};

var table = Resources["InfoTableFunctions"].CreateInfoTable(params);

table.AddField({name: "min", baseType: "NUMBER"});

table.AddField({name: "max", baseType: "NUMBER"});

table.AddField({name: "from", baseType: "DATETIME"});

table.AddField({name: "to", baseType: "DATETIME"});

table.AddRow({min: min, max: max, from:values.rows[0].timestamp, to: values.rows[count-1].timestamp});

var result = table;

This should do the trick, sorry made it in hurry.

I recomend that you create a DataShape as well which corresponds with above schema. (i.e min,max,from,to) and assign this datashape to output parameter of your service which must be type of infotable of coarse.

Now you can call QueryPropertyHistory (or QueryStreamEntriesWithData, or even QueryDataTableEntriesWithData) and take its result as input parameter for your calculate function, than you only need to set the PropertyName1 and 2 to which columns you want to use.

Hope that helps.

Let me know it that is working, havent tried it.