trustfall — How to Query (Almost) Everything

This repository contains the trustfall query engine, which can be used to query any data source or combination of data sources: databases, APIs, raw files (JSON, CSV, etc.), git version control, etc. For a 10min video introduction to the project, see the "How to Query (Almost) Everything" talk from the HYTRADBOI 2022 conference.

Demo showing the execution of the cross-API query: "Which GitHub Actions are used in projects on the front page of HackerNews with >=10 points?"

The demo executes the following query across the HackerNews and GitHub APIs and over the YAML-formatted GitHub repository workflow files:

{
  HackerNewsTop(max: 200) {
    ... on HackerNewsStory {
      hn_score: score @filter(op: ">=", value: ["$min_score"]) @output

      link {
        ... on GitHubRepository {
          repo_url: url @output

          workflows {
            workflow: name @output
            workflow_path: path @output

            jobs {
              job: name @output

              step {
                ... on GitHubActionsImportedStep {
                  step: name @output
                  action: uses @output
                }
              }
            }
          }
        }
      }
    }
  }
}

This demo is part of the "How to Query (Almost) Everything" talk from the HYTRADBOI 2022 conference. Instructions for running the demo are available together with the source code in the demo-hytradboi directory: link.

Example Trustfall implementations

• HackerNews APIs, including an overview of the query language and an example of querying REST APIs.
• RSS/Atom feeds, showing how to query structured data like RSS/Atom feeds.
• airport weather data (METAR), showing how to query CSV data from aviation weather reports.

Using Trustfall over a new data source

The easiest way to plug in a new data source is by implementing the BasicAdapter trait.

Python bindings are available, and are built automatically on every change to the engine; the most recent version may be downloaded here. A getting started guide for Python is forthcoming (tracking issue); in the meantime, the best resource is the Python bindings' test suite.

Directory Registry

• trustfall is a façade crate. This is the preferred way to use Trustfall.
• trustfall_core contains the query engine internals
• trustfall_derive defines macros that simplify plugging in data sources.
• pytrustfall contains Trustfall's Python bindings
• trustfall_wasm is a WASM build of Trustfall
• trustfall_filetests_macros is a procedural macro used to generate test cases defined by files: they ensure that the function under test, when given an input specified by one file, produces an output equivalent to the contents of another file.
• experiments contains various experimental projects such as the Trustfall web playground.

Copyright 2022-present Predrag Gruevski.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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