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• jsonb_extract_path   ---- this expression specifies the PATH necessary to get the last field entered in the path; the result is a json object and will be enclosed in double-quotes
• jsonb_extract_path_text   ---- this expression does the same thing as jsonb_extract_path, but returns a TEXT object (no quotes)
• jsonb_array_elements   ---- this expression is used for extracting values within an array object
• table_name_or_alias.jsonb #>> '{path_of_fields_in_the_hierarchy_separated_by_commas}' 
  • Example: audit_loan.jsonb #>> '{loan, metadata, updatedByUserId}'  — this will get the value for "updatedByUserId"

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SELECT
     al.id as audit_loan_id,
     jsonb_extract_path_text (al.jsonb, 'loan', 'status', 'name') AS loan_status__name,
     jsonb_extract_path_text (al.jsonb, 'loan', 'metadata', 'updatedByUserId') AS loan_updated_by_user_id
FROM
     folio_circulation.audit_loan AS al

The following expression will also get the third-level values:

SELECT
     al.id as audit_loan_id,
     al.jsonb #>> '{loan, status, name}' AS loan_status__name,
     al.jsonb #>> '{loan, metadata, updatedByUserId}' AS loan_updated_by_user_id
FROM
     folio_circulation.audit_loan AS al

Extracting Arrays 

-- 1. Embedded Arrays embedded in text objects

In the previous examples, the elements being extracted were "text objects" within the table's JSON array, and were denoted by curly brackets { }. In this next example, we need to extract multiple values from an "array" object (denoted by square brackets [ ] ) that is embedded in a hierarchy of text elements. This calls for nested json extract statements, a structure very similar to what we used in Access with nested "GetField" and "GetXXXBLOB" functions.

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