Ruby retrieve json object, query

Question

So I have this model Foo with nested fields,

<id: 1, name: "blah", condition: "{\"condition_type\":\"BAR\",\"number\":\"1\""\}">

I want to get the list of Foos with condition type Bar only. I have tried

    JSON.parse(Foo.select(:condition)).where({"condition_type"=>"BAR"})

but doesn't work. I would appreciate any help!

Anthony · Accepted Answer · 2014-10-21 11:41:43Z

1

There's a slight syntax error in your JSON (I think an extra quote at the end but at the end of JSON.parse(Foo.select(:condition)) you're now working with a JSON object (which I think you're aware of. If you were to say:

JSON.parse(Foo.select(:condition)).class you would get a hash.

[12] pry(main)> json
=> {"condition_type"=>"BAR", "number"=>"1"}
[13] pry(main)> json.class
=> Hash

That all said, you can use the the Enumerable#keep_if method like this on a hash:

[26] pry(main)> json = JSON.parse(condition)
=> {"condition_type"=>"BAR", "number"=>"1"}
[27] pry(main)> json.keep_if { |k, v| k == "condition_type" && v == "BAR" }
=> {"condition_type"=>"BAR"}

The combined method would look like this:

JSON.parse(Foo.select(:condition)).keep_if { |k, v| k == "condition_type" && v == "BAR" }

answered Oct 21, 2014 at 11:41

Anthony

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2 Comments

user2418838 Over a year ago

thanks a lot it helped!! but I was wondering if there is any simpler way of doing it without using blocks, just by using query commands.

Anthony Over a year ago

are you storing the json as a text field in your database? If so what database?

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