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Rest Gateway Expressions

The Aerospike REST gateway 1.7.0 and newer supports filter expressions added in server 5.6. The now deprecated predicate expressions are supported in REST gateway 1.11.0 and older.

Important: The DSL used to define predicate expressions can also be used to define filter expressions.

There are two ways to define a filter expression and provide it as part of a URL query parameter. For more information on which APIs support filter expression take a look at the [Swagger UI API documentation] Aerospike REST Gateway API Documentation. The first way to define a filter expression, is to use the DSL. The second, is to use one of our supporting client libraries to define an expression and serialize it to a Base64 encoded string using the provided APIs for that language.

For a quick overview of the DSL please take a look at our "Dealing with Predicate Expression Filters" blog post series.

  1. Dealing with Predicate Expression Filters in Aerospike REST Gateway (Part 1)
  2. Dealing with Predicate Expression Filters in Aerospike REST Gateway (Part 2)

The second method requires that we write a small amount of code to build an Expression object and serialize it to a base64 encoded string. Currently, the only languages that support this feature are C, C#, and Java with more to come. You can either setup a small project in your favorite IDE or you can use Aerospike's coding sandbox.

For example, the following creates an expression using the Java Client API that returns true or false if the product of intBin1 and intBin2 is greater than 15. You can copy and paste the following code snippet into the sandbox to try it out for yourself.

Note: The sandbox does not require, nor does it allow, you to define an entry class.

import com.aerospike.client.exp.Exp;
import com.aerospike.client.exp.Expression;

Expression exp=Exp.build(
    Exp.gt(
        Exp.mul(
            Exp.intBin("intBin1"),
            Exp.intBin("intBin2")
        ),
    Exp.val(15L)
    )
);
System.out.println(exp.getBase64());

which will print out your base64 encodes expression kwOTFpNRAqdpbnRCaW4xk1ECp2ludEJpbjIP. The base64 encoded string can now be provided as a filter_expression query parameter.