Typically a query by example consists of AND operations.
handler.query ({age:5, height:0.7});
Using constraints just gives us the opportunity for more complicated AND operations
var c = enums.CONSTRAINTS; handler.query ( age: handler.constraints([[c.LTE,.9],[c.GTE,.5]]), age: handler.constraint([c.LT,7]));
Sometimes you want to to OR operations – for example people under 10 or over 25. Not all underlying databases even have an OR capability (for example DataStore), but database abstraction provides a consistent way to do OR operations across all supported back ends.
How to do ORS
The following syntax applies to all backends
Lets say you want to do these 2 queries and combine the results
handler.query ({color:'red'});
handler.query ({size:'big'});
Just make an array of queries
handler.query ([{size:'big'},{color:'red'}]);
You can mix in constraints as well if you want
var c = enums.CONSTRAINTS;
handler.query ([ {"location.country":"usa", "location.state":handler.constraints([c.IN,["il","ny"]])}, {"location.country":"uk", "location.city":"london"} ]);
Duplicates are automatically removed (if records qualify for more than one query they are returned only once)
See Database abstraction with google apps script for more on this.
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