Скачать или смотреть Building a Drag and Drop Feature with JSON Data Structures in Postgres

Learn how to structure and retrieve JSON data for your `drag and drop` feature in Postgres, allowing for organized arrays of patients and their recommendations.
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This video is based on the question https://stackoverflow.com/q/68660277/ asked by the user 'MMettille' ( https://stackoverflow.com/u/15586672/ ) and on the answer https://stackoverflow.com/a/68662527/ provided by the user 'Ftisiot' ( https://stackoverflow.com/u/7605762/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction to the Problem

When developing a drag and drop feature for a client project, one of the challenges is structuring the data in a way that it aligns with the expected output. The goal is to create an array of objects where each object represents a patient, containing an ID and an array of recommendations derived from various providers.

The desired JSON structure should look like this:

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

Where the recommendations array could include provider names like:

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

To achieve this, we need to explore how to combine data from multiple tables in Postgres using JSON functions effectively.

Understanding Your Database Structure

Before diving into the SQL solutions, let's clarify the tables involved:

Patient Table: Stores patient records with id and bucket_id fields.

Patient Provider Table: Associates patients with providers through provider_id and patient_id.

Provider Table: Contains provider information including program names.

The relationships between these tables are established through foreign keys, enabling us to query and gather the necessary data efficiently.

Constructing the Solution

Step 1: Retrieving Recommendations

First, we want to retrieve the recommendations for each patient. This can be achieved with the following SQL query:

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

This query will return the patient IDs alongside an array of distinct provider programs associated with them.

Step 2: Structuring the JSON Output

Now, we will leverage the json_build_object feature to format the results into JSON objects:

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

The result of this query will provide us with objects that include patient IDs and their recommendations in the desired format.

Step 3: Aggregating Results into an Array

To get a single result set encapsulated in a JSON array, we can utilize the json_agg function. Wrapping the previous query in another layer allows us to aggregate these JSON objects:

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

This will output a JSON array containing all patient objects structured as required.

Step 4: Adding Extra Array Encapsulation (Optional)

If you need an extra layer (as mentioned in your original structure requirement), you can wrap the main object with json_build_array as follows:

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

Conclusion

Through combining SQL querying and utilizing Postgres's powerful JSON functions (json_build_object and json_agg), we can effectively generate the structured data needed for your drag and drop feature. This approach not only organizes the data but also streamlines the process of extracting and utilizing it in your application.

By following the structured steps outlined above, you're now equipped to create a seamless experience for your clients and improve their day-to-day workflows. Best of luck, and don't hesitate to reach out for help if needed! Happy coding!