Fixing Invalid OpenAPI Specs In Pygeoapi With EDR And I10n

Oct 22, 2025 by Dimemap Team 59 views

Hey guys, have you ever run into a situation where your OpenAPI 3 spec generated by pygeoapi went wonky, especially when dealing with EDR (Environmental Data Retrieval) collection resources that use internationalized descriptions (i10n)? Well, you're not alone! It's a pretty common issue, and in this article, we'll dive deep into what's going on, how to reproduce it, and most importantly, how to get things back on track. We're going to use simple words to help you understand what's happening. Ready to get started? Let's go!

The Core of the Problem: i10n Descriptions and OpenAPI

Let's cut to the chase, The root of the problem lies in how pygeoapi handles i10n descriptions within its OpenAPI generation for EDR resources. Instead of generating the expected string for the descriptions, it's incorrectly outputting dictionaries. This means that when you use EDR collections that have descriptions with internationalization, the generated OpenAPI spec becomes invalid. The description fields for the retrieval endpoints, which are meant to be simple strings explaining what the endpoint does, end up being dictionaries with language codes as keys and descriptions as values. This is not what the OpenAPI specification allows and will cause problems when you try to use tools that rely on the spec. Basically, the OpenAPI spec is the blueprint for your API, and if the blueprint is wrong, things don’t work as they should. Now, imagine you're a developer trying to use an API based on an invalid spec. You'd likely run into errors and compatibility problems, which is the kind of situation we want to avoid. The impact is pretty clear: it causes tools that use the OpenAPI spec (like API documentation generators, client libraries, and API gateways) to break or malfunction.

Impact of the Bug

Invalid OpenAPI Specification: The core issue is the generation of an invalid OpenAPI 3.0 specification. This invalidation stems from the incorrect handling of internationalized descriptions (i10n) within EDR resources. Instead of generating the expected string for descriptions, the process outputs dictionaries. This violation of the OpenAPI standard results in errors during validation and parsing by various tools.
Documentation and Tooling Issues: Because the spec is broken, tools that rely on this OpenAPI spec, like API documentation generators or client libraries, can't correctly interpret the API's structure. This leads to broken documentation and prevents developers from correctly using the API through these tools. It is like trying to build a house with a blueprint that makes no sense; the final product will not work as expected.
Operational Problems: It can cause integration problems, where API gateways and other systems that use the OpenAPI specification fail to integrate correctly with the API. This failure blocks the deployment and operations that rely on correct API descriptions.
Summary Field Problems: Beyond just the description field, the summary fields are also affected. Because the summary fields take their value from these i10n descriptions, they also become malformed, making the problem worse as they also give the wrong short descriptions of what API calls do.

Steps to Reproduce the Issue: A Practical Guide

So, how do you see this issue in action? Let's take a look at the steps to reproduce the invalid OpenAPI spec. This will help you understand the problem and how to verify if you're affected.

Setting Up the Environment

Define a Collection: Start by defining an EDR collection within your pygeoapi configuration. It is very important that you configure this collection to use an EDR provider and uses internationalized descriptions. For instance, you could use a setup where descriptions are written in multiple languages (e.g., English, French, Spanish). The setup requires specific data and configurations.
Configuration File: Ensure that your configuration file correctly defines the resources. Each resource should specify its type, title, and description, including i10n support. The descriptions are provided with language codes to support multiple languages. Your resources should reference the correct EDR providers to handle data retrieval. For example, for the collection, your configuration might look something like this:
```
resources:
  frost-server:
    type: collection
    title: FROST-Server
    description:
      en: The Fraunhofer Open-source SensorThings Server.
    providers:
      - type: edr
        name: pygeoapi.provider.sensorthings_edr.SensorThingsEDRProvider
        data: https://emotional.byteroad.net/FROST-Server/v1.1/
```

Triggering the OpenAPI Generation

After setting up your configuration, you will need to generate the OpenAPI specification. This can usually be done by accessing a specific endpoint in pygeoapi that serves the OpenAPI document. You're usually able to access your API's OpenAPI specification, often via a URL like /openapi. This will trigger the generation of the spec based on your configuration.

Observing the Output

Inspect the Output: Open the generated OpenAPI specification (usually in YAML or JSON format) in a text editor or a tool that can display and validate OpenAPI specs. Specifically, look at the sections describing your EDR collection's retrieval endpoints (e.g., /collections/{collectionId}/area).
Verify the Description: Within the endpoint descriptions, examine the description and summary fields. The description field should contain a string describing the endpoint, while the summary field provides a brief summary. However, with the bug, you will see something like this:
```
/collections/frost-server/area:
  get:
    description: &id001
      en: The Fraunhofer Open-source SensorThings Server.
    summary: 'query {''en'': ''The Fraunhofer Open-source SensorThings Server.''} by area'
```
Instead of a clean string, you will see the dictionary. The summary field will also show an incorrect value, which means the issue affects both description and summary.

Expected vs. Actual Behavior: Spotting the Discrepancy

Let's get even more specific about what's expected versus what's actually happening. By comparing these two, you will immediately grasp the problem and why it’s a big deal.

What Should Happen (Expected Behavior)

In an ideal world, when pygeoapi generates the OpenAPI spec for an EDR collection with i10n descriptions, we expect clean, easy-to-read strings. More specifically, the description and summary fields in the generated OpenAPI spec should appear as simple strings. For example, the OpenAPI spec should use a string for the description across each of the collection's retrieval endpoints:

/collections/frost-server/area:
  get:
    description: The Fraunhofer Open-source SensorThings Server.
    summary: 'query Frost-server by area'

What Actually Happens (Actual Behavior)

Instead, here is what you're likely to see when the bug is present. The description field contains a dictionary with language codes and their corresponding descriptions. Also, the summary field incorporates the malformed dictionary, causing the summary to be inaccurate and unhelpful. The OpenAPI spec should include strings, however it does not.

/collections/frost-server/area:
  get:
    description: &id001
      en: The Fraunhofer Open-source SensorThings Server.
    summary: 'query {''en'': ''The Fraunhofer Open-source SensorThings Server.''} by area'

Diving into the Code: Where the Issue Resides

To understand this bug thoroughly, we need to locate where the issue exists within pygeoapi's codebase. Unfortunately, to pinpoint the exact lines of code, you'll need to dig into the pygeoapi source code. Look for the parts of the code responsible for generating the OpenAPI specifications. You'll need to familiarize yourself with how pygeoapi handles internationalized descriptions and the process of constructing the OpenAPI documents. If you're comfortable with Python and the structure of pygeoapi, then you can look for the parts that generate the OpenAPI spec.

Key Areas to Investigate

Configuration Parsing: Start by checking how pygeoapi parses the resource configurations, specifically the handling of description fields. Ensure that the values are correctly interpreted as strings or, in the case of i10n, a dictionary of strings.
OpenAPI Generation Logic: Then, find the code responsible for generating the OpenAPI specification from the parsed configurations. You will have to understand how the code processes the configurations and includes the descriptions in the OpenAPI document. This part is critical for understanding the bug.
Description Field Processing: Specifically, examine how the description fields are included in the OpenAPI document. You should be able to see where the strings for the description are extracted and inserted into the OpenAPI structure.
String Formatting: The code might incorrectly serialize the i10n description dictionaries into strings, instead of extracting the correct localized strings. Make sure the code extracts the correct descriptions.

Environment Details: The Setup for Reproduction

To make sure you can replicate the issue, here are the environment details. This includes the operating system, the version of Python you're using, and the specific version of pygeoapi you're working with. This information is key because these details directly influence whether the bug appears.

Specifications

Operating System: The bug is not specific to any particular OS. It has been confirmed to occur on multiple operating systems (like Windows, macOS, and various Linux distributions) as long as the necessary environment is in place.
Python Version: The issue is reproducible with Python 3.10. While other versions of Python may be affected, this version is the one that's been confirmed to reproduce the issue. It's recommended to use this version or a compatible one when trying to reproduce or fix the bug.
pygeoapi Version: The bug is present in pygeoapi version 0.21.0. This means that if you're using this version, you're likely to encounter the issue. Later versions may or may not include fixes, so always check the release notes.

Resolving the Issue: Finding a Solution

Fixing this issue means modifying the pygeoapi code to ensure that the OpenAPI spec is generated correctly when dealing with i10n descriptions. It will need to handle the descriptions as strings, not dictionaries. Here is how you can approach solving this issue.

Potential Solutions

Modify the OpenAPI Generation Code: The primary solution involves changing the code that generates the OpenAPI specification. You'll need to modify the code to correctly handle the i10n descriptions. Instead of including the full dictionary, extract the appropriate description based on the user's preferred language or a default language.
Extract Descriptions: Before inserting the description into the OpenAPI spec, determine which language to use. If the user's preferred language is available, use that. Otherwise, use a default language (like English) as a fallback.
Ensure String Formatting: Make sure all description values are inserted as strings in the OpenAPI spec. Make sure that the generated output from the code matches the expected output in the 'Expected behavior' section.
Testing: After making the changes, test the modified code to ensure that the OpenAPI spec is valid and that the descriptions are correctly formatted as strings. You can use OpenAPI validators to make sure that the generated spec is correct.

Conclusion: Wrapping Things Up

So, guys, you've seen the issue: how pygeoapi struggles with i10n descriptions in its OpenAPI generation for EDR resources. We've discussed how to spot the issue, what the impact is, and how to start fixing it. Remember to always validate your OpenAPI specs and test your changes thoroughly. By addressing these issues, you will make your API more user-friendly and make sure it integrates better with other systems. Keep up the great work and have fun!