Скачать или смотреть How to Evaluate Commands Inside a jq Pipeline for JSON Transformation

A detailed guide on how to evaluate commands within a jq pipeline to manipulate JSON data efficiently. Learn how to integrate external scripts for dynamic value computation!
---
This video is based on the question https://stackoverflow.com/q/75419250/ asked by the user 'Rafag' ( https://stackoverflow.com/u/2282433/ ) and on the answer https://stackoverflow.com/a/75422111/ provided by the user 'Philippe' ( https://stackoverflow.com/u/2125671/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Evaluating command inside JQ pipeline

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Transforming JSON with External Command Evaluation in jq

JSON data manipulation can often present challenges, especially when requiring external computations within a data transformation tool like jq. In this post, we will explore how to incorporate shell commands into a jq pipeline, allowing complex JSON transformations using an external script. This guide will walk through an example scenario and provide a step-by-step solution.

The Challenge

Suppose we have the following JSON data structure in a file called mappings.json:

[[See Video to Reveal this Text or Code Snippet]]

Our goal is to transform this JSON data to include an additional field called alternative_model, computed using an external bash script. The desired output looks like this:

[[See Video to Reveal this Text or Code Snippet]]

Proposed Solution

To achieve this, we need to design a bash script, let's say myscript, that computes the value for alternative_model. Here’s how to do it.

Step 1: Create the External Script

First, we define the content of myscript as follows:

[[See Video to Reveal this Text or Code Snippet]]

This script simply echoes a formatted string based on the input it receives.

Step 2: Shell Script for Processing JSON

Next, we create a bash script that handles reading the JSON and integrating the external command using jq. Here’s the complete code snippet:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Code

Defining Input: Set the variable input to your JSON file path.

Function Declaration: A function named alternative_models reads the model IDs and computes their respective alternative models.

Iterate through IDs: We use a loop to iterate through each ID obtained from the JSON.

Extracting Model Names: For each ID, the model name is extracted using jq.

Calling the External Script: The external script is executed with the model name, and the result is captured.

Building the Result: Using jq, a new JSON object is constructed containing each ID and its computed alternative model.

Final Output: The jq command consolidates the newly constructed JSON back into the initial structure.

Important Note on JSON Structure

Before running the script, ensure that your original mappings.json adheres to valid JSON standards. For instance, in this case, a comma at the end of the model line may lead to errors during parsing.

Conclusion

Integrating bash commands into a jq pipeline can significantly enhance the flexibility of JSON data transformations, especially when dynamic values are involved. Whether you're automating processes or generating reports, this method can be a powerful tool.

Feel free to test this solution and extend it further according to your needs. Happy scripting!