API Gateway Expressions Reference
Bondy API Specification use a logic-less domain-specific language (internally called "Mops") for data transformation and dynamic configuration.
Notice
The expression language operates on the API Context and it works by expanding keys (or key paths) provided in a context and adding or updating keys in the same context object.
This reference assumes you are familiar with the API Context schema.
Overview
We call Mops "logic-less" because there are no if statements, else clauses, or for loops. Instead there are only tags. Some tags are replaced with a value, some nothing, and others a series of values. This document explains the different types of Mops tags[1].
Expressions
Expressions are strings containing one or more Tags.
You can use an expression in an API Gateway Specification object property when its value is of type expression.
An expression is a promise i.e. a proxy for a value not necessarily known when the promise is created.
Promise Type
The promise type syntax used across the documentation is () => DATATYPE where DATATYPE is the type of value the promise should be fulfilled with i.e. () => string means that once the expression is evaluated, and thus the promise fulfilled, the value should be of type string.
Tags
Tags are indicated by the double mustaches. {{request}} is a tag, as is {{defaults.timeout}}.
Mops always operates on an API Context, a map that contains