Primer

Module Expressions
parse(expression)
Parse an expression.
This returns a JSON that contains a list of query parts, and methods for interacting with the query.
Arguments
expression { Expression } Any valid expression.
const expressions = require('expressions')
return expressions.parse({
    $toString: '$$NOW'
})
Returns
{ * } The ran expression.
{
    "object": "result",
    "data": {
        "depth": 1,
        "fullPath": "$toString",
        "input": {
            "$toString": "$$NOW"
        },
        "path": "$toString",
      }}
run(expression, root)
This runs the command in the context of the current database.
Arguments
expression { Expression } Any valid expression.
const expressions = require('expressions')
​
return expressions.run({
    $toString: '$$NOW'
})
Returns
{ * } The ran expression.
{
    "object": "result",
    "data": "Wed Oct 07 2020 16:14:16 GMT+0000 (Coordinated Universal Time)"
}
evaluate(expression, root)
This evaluates an expression, running the expression and returning a JSON that contains a list of query parts, and methods for interacting with the query. Arguments
expression { Expression } Any valid expression.
const expressions = require('expressions')
​
return expressions.evaluate({
    $toString: '$$NOW'
})
Returns
{ * } The ran expression.
{
    "object": "result",
    "data": {
        "accessScope": {
            "allow": 0,
            "context": {
                "object": ""
            },
            "grant": 0,
            "instanceRoles": [],
            "object": "ac",
            "org": {
        ...}
      }
    }
  }
Pipelines
Pipeline aggregation allows for querying, aggregating, and transforming data in multiple stages in real-time through a single API request. While query arguments allow for making simple, single-stage queries through the API, pipelines allow for more complex searches, aggregations and transformations.
pipeline.parse(expression)
This returns a JSON that contains a list of query parts, and methods for interacting with the query.
Arguments
expression { Expression } Any valid expression.
const expressions = require('expressions')
​
​
return expressions.parse({
    $toString: '$$NOW'
})
Returns
{ * } The ran expression.
{
    "object": "result",
    "data": {
        "depth": 1,
        "fullPath": "$toString",
        "input": {
            "$toString": "$$NOW"
        },
        "path": "$toString",
        "type": "Expression$operator",
        "value": {
            "expression": {
              ...
            }
          }
        }
      }
pipeline.run(expression, input)
This runs the command in the context of the current database.
Arguments
expression { Expression } Any valid expression.
const expressions = require('expressions')
return expressions.pipeline.run([
        {
          $project: { $split: ['$$ROOT', ' '] }
        }
​
      ],
      ['This is a test', 'we are testing pipelines', 'Medable is cool']
      ).toArray()
Returns
{ * } The ran expression.
{
    "data": [
        [
            "This",
            "is",
            "a",
            "test"
        ],
        [
            "We",
            "are",
            "testing",
            "pipelines"
        ],
        [
            "Medable",
            "is",
            "cool"
        ]
    ],
    "hasMore": false,
    "object": "list"
}
Arguments
expression { Expression } Any valid expression.
input { Array|Cursor = null } An array or cursor to serve as initial input.
pipeline.evaluate(expression, input)
This evaluates an expression, running the expression and returning a JSON that contains a list of query parts, and methods for interacting with the query.
Arguments
expression { Expression } Any valid expression.
const expressions = require('expressions')
return expressions.pipeline.evaluate([
        {
          $project: { $split: ['$$ROOT', ' '] }
        }
​
      ],
      ['This is a message', 'Pipelines are being tested', 'Sky is blue']
      )
Returns
{ * } The evaluated expression.
{
    "object": "result",
    "data": {
        "accessScope": {
            "allow": 0,
            "context": {
                "object": ""
            },
            "grant": 0,
          }}}
Last modified 1yr ago