JSON Key Selector

Summary

The Json Key Selector is used in all RestProxyExts (RestPointProxyExt and ArtifactProxyExt of the ArtifactDefinition). It is also used in the Artifact Selector.

It allows selection of a value in a JSON file (see HTTP and Web APIs for more details on the JSON format).

Implementation

It is present in the RestPointProxyExt Selector and the ArtifactDefinition ArtifactProxyExt properties and is used with the syntax described below.

In the RestPointProxyExt

In the ArtifactDefinition

Syntax

Remember, the JSON data format is characterized by a nesting of objects and tables of data. Data is always accessible through a key in an object or an index for an array.

In the Json Key Selector syntax, each key or index is separated from the next by a period (.).

For example, for the following JSON:

JS

{
    "currently": {
        "time": 1519817193,
        "summary": "Windy with Scattered Clouds",
        "temperature": -2.04,
		"coordinates": "2.3522219, 48.856614",
		"day": "15"
    },
    "hourly": {
        "summary": "Windy and cloudy all day.",
        "data": [
            {
                "time": 1519815600,
                "summary": "Windy with Scattered Clouds",
                "temperature": -2.28
            },
            {
                "time": 1519819200,
                "summary": "Windy with Scattered Clouds",
                "temperature": -1.75
            }
        ]
    },
    "daily": {
        "summary": "Light rain tomorrow until Saturday, temperatures rising to 10°C Sunday.",
        "data": [
            {
                "time": 1519772400,
                "summary": "Windy all day and cloudy from start of the afternoon.",
                "temperatureHigh": 0.03,
                "temperatureLow": -0.41
            },
            {
                "time": 1519945200,
                "summary": "Light wind until afternoon and cloudy throughout the day.",
                "temperatureHigh": 8.53,
                "temperatureLow": 5.24
            }
        ]
    }
}

To select the temperature at the moment of the request:

CODE

currently.temperature

To select the expected temperature in one hour:

CODE

hourly.data.1.temperature

To select the maximum temperature for the current day

CODE

daily.data.0.temperatureHigh

To select the last temperature, use the keyword "last"

CODE

daily.data.last.temperatureHigh

To select the first temperature, use the keyword "first"

CODE

daily.data.last.temperatureHigh

To select all the values (for histories for example), use the keyword "all"

CODE

daily.data.all.temperatureHigh

To select all the values in reverse order (for histories for example), use the keyword "allRevert"

CODE

daily.data.allRevert.temperatureHigh

To make an average on the numerical values in an array, you can use the average feature

CODE

daily.data.all.temperatureHigh.avg()

To find the highest value of the numerical values in an array, you can use the max feature

CODE

daily.data.all.temperatureHigh.max()

To find the smallest value of the numerical values in an array, you can use the min feature

CODE

daily.data.all.temperatureHigh.min()

To make a sum of the numerical values in an array, you can use the sum feature

CODE

daily.data.all.temperatureHigh.sum()

To filter some values, you can use the filter predicate feature

CODE

data.filter('id','myId').first.value

To filter on inner keys, you must escape the points with square brackets ex: filter('firstKey[.]innerKey','myValue')

To split a string into several values, use the keyword "split" with the delimiter as parameter

CODE

currently.coordinates.split(',').item(0)

To convert some values from String to double or boolean, use the keyword "toDouble" or "toBoolean"

CODE

currently.day.toDouble

The table indices start at zero.

The avg(), max(), min() and sum() functions are terminal operations. Adding another key after the function won't work