Keys Class Reference

Keys is used to handle the transformation between classified values (i.e. from one type of data definition to another). More...

List of all members.

Static Public Attributes
static string	name
static array	data

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Detailed Description

Keys is used to handle the transformation between classified values (i.e. from one type of data definition to another).

A Keys object has a list of key - value pairs and a name. The value() function can be used to get a stored value for a specific key. A global javascript function cls() is used to define the usage of a Keys element within a Binding. Using Keys is fast, because it allows the core engine to evaluate reclassifications without issuing calls to Javascript routines. The name / value pairs must be provided as an array / simple JSON expression (see examples below).

Basic usage example:

// create Key object
var key = new Keys;
key.name = 'specieskey';
key.data = { 'picea abies': 'pa', 'pinus sylvestris': 'ps'};

// use the key in a data binding: classify the source column 'SPECIES' using the 'specieskey' defined above
// (e.g. translate 'picea abies' to 'pa') and store the result to the bound column 'Species'.
var bind =  {  Species: cls('SPECIES', 'specieskey') };

Creating many Keys objects per hand might be cumbersome. In that case Keys can be loaded automatically using a Javascript function:

// Helper function that loads
//   classification schemes (and their translation to motive-format)
//   from a simple text-based table with columns 'name', 'key', 'value'
function loadClasses(file_name)
{
        var ds = new DataSource;
        ds.open('csv', file_name);
        var last_name = "???";
        var keys, data;
        while (ds.next()) {
                if (ds.value("name")!=last_name) {
                        if (ds.at()>0) {
                           keys.data = data;
                           print("loaded key-transformation for", keys.name);
                        }
                        keys = new Keys;
                        last_name = ds.value("name");
                        keys.name = last_name;
                        data = [];
                }
                data[ds.value("key")] = ds.value("value");
        }
        if (ds.at()>0) {
                keys.data = data;
                print("loaded key-transformation for", keys.name);
        }
}

//   example file:
//   name;key;value
//   species;picea abies;pa
//   species;pinus sylvestris;ps
//   dbh_1;1;2
//   dbh_1;2;4

Attention:

There are several options how the functionality of Keys could be extended.

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Member Data Documentation

array Keys::data [static]

the classification array as a list of key / value pairs in JSON Notation.

string Keys::name [static]

the name of the classifcation. This name is used to refer to a classification when using the GlobalScope::cls() function.

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The documentation for this class was generated from the following file:

• E:/dev/motive/client/src/apidoc/keywrapperjs.cpp