Probably your problem in quotation: Submission.joins(:fmp_session). Id | integer | not null default nextval('fmp_sessions_id_seq'::regclass)Īnd the schema create_table "fmp_sessions", force: :cascade do |t| Additionally you should know Column | Type |Modifiers To show the database portion, here is the table description (from psql) and the the schema.db segments for this table. Help me find the right query to join one table to another and search an json array field for a specific string. The search is not as optimized as it would be with an expression index on the path you’re querying, but still uses the index. In theory, this would search the project_data array, and searches it with #> so it doesn't matter how many elements are in the array - but I have tried close to 40 machinations of the query and am stuck. The most important thing here is that json performed a sequential scan, which means that PostgreSQL goes record by record, sequentially, until the condition is satisfied also remember that the JSON content is going to be reparsed for each record, which can be slow for complex structures. I was thinking something like this: Submission.joins(:fmp_session).where( I'd rather stick with activerecord or sql (or mix and match) and leave AREL alone. So what I want is an active record array of all submissions if the fmp_session.project_data 'type' json key equals 'CREW'. In PostgreSQL, path expressions are implemented as the jsonpath data type and can use any elements described in Section 8.14.7. The main model is Submission, which has_one :fmp_session - FmpSession has a field : project_data, which is a postgresql :json type field, containing a json array. I want to get a list of Model which have a specific "type" field inside of a json array column using postgresql.Ĭould someone point me in the right direction, also, I am fine with this being a class level method instead of a scope, I just need a list of all the Model.objects. Feel free to edit this to make it more clear. We refrained from refactoring it to a gem/DSL, so the code examples read a little nicer.Seriously struggling to come up with a rational scope. I have come up with a list of queries using ActiveRecord and Postgres' JSON data type. If you have any questions, feel free to reach out. Yet, the master branch combines them into more complete solution. Also note the heitor, tom and dmitry branches, which have different approaches to the same problem. Old records stay valid and usable if the default value of the schema changes, and querying inside the description is ok due to PostgreSQL power with JSONB fields.Ī complete version of this idea can be seen in this GitHub repo. With the schema definition and a little Rails magic, we also enable validations. We are now able to have a relational database delivering multiple records of the same table, each one with different set of attributes. Remember that with JSONB, we have indexes called GIN / GiST to help with performance. # description->sound = 'Pioneer' Vehicle. We want every new instance of vehicle to have its schema filled by a default value declared in the database table. To query JSON data, build your SELECT statement, as -> returns value as exact JSONB data type -> returns value as text. Required fields are also being declared in the schema for later validations. This enables us to have a different set of attributes for each record of the table. The schema defines attributes, telling us their type and default value. Documentation to the JSON operators used below. It held a schema and a description keeping its characteristics. I have come up with a list of queries using ActiveRecord and Postgres' JSON data type. After we did some brainstorming and white board sessions, we decided to start with a Model called Vehicle. This was a joint effort between me, Tom Rothe and Dmitry Parshenko. That was easily solved with a JSON field, but we also wanted to support validations on this field – validations that are assigned to the model at the time of creation. Its a great way of working with JSON attributes on your models, which can be an option for storing. We knew that the columns for one particular model would need to change over time. Quickly Familiarise Yourself with Postgres jsonb in Rails. JSON dynamic attributes with Rails we are 3-in-1: a technologist, a trainer, an organizer.
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