Ecto query with fragment

0
votes

I have the following query in my pipeline:

where([e], fragment("?->>? = ?", e.fields, ^field_name, ^field_value))

e in this case stands for event. What is the first parameter of the fragment method call doing?

1
jqueryelixirecto

1 Answers

1
votes

The first parameter of the call to Ecto.Query.API.fragment/1 is the template for the fragment to be send to the database.

Here it is a Postgres function to retrieve a JSON object field as text. That said,

fragment("?->>? = ?", e.fields, ^field_name, ^field_value)

is literally “where nested field with a name field_name in the JSONB field has a value equal to field_value.”