How to Cast PostgreSQL JSONB Data to Float for Mathematical Operations?

Casting PostgreSQL JSONB Data to Float

In PostgreSQL, attempting to perform mathematical operations with JSONB data often results in errors like "operator does not exist" when the conversion to float is not explicitly specified.

To resolve this issue, consider the different JSON value retrieval operators:

• -> (Arrow Operator): Returns JSON values as JSON.
• ->> (Double Arrow Operator): Returns text values.

Since floats are stored as text in JSONB, it's necessary to use the ->> (Double Arrow) operator to extract the string representation of the float before attempting to cast it to float.

For example, consider the following query:

SELECT (json_data->'position'->'lat')::float + 1.0 AS lat
FROM updates
LIMIT 5

Here, the -> (Arrow) operator is initially used to extract the JSON object 'position'. The ->> (Double Arrow) operator is then used to retrieve the string value of 'lat'. Finally, the ::float casting operator is used to convert the string to a float.

By utilizing the appropriate JSON value retrieval operator, you can successfully cast JSONB values to floats in your PostgreSQL queries.

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