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rails: How to find entries with empty arrays

I've got an issue finding empty arrays in a SQLITE table.

I serialized the product_category param, which works well for saving arrays into my DB, as follows:

serialize :product_category, Array

The following is query to find all empty arrays for this param, but its giving me an nil error:

Product.where(product_category: []).first

How do i find Products where the product_category has no values in its array?

I tried using {} instead of [] as suggested in a similar POSTGRESS related question.

Does anyone know the right way?

Solution

  • I have tried this on mysql, this works for me, please try.

    #product.rb
serialize :product_category, Array

#rails console
>> product = Product.new
>> product.product_category = []
>> product.save
>> Product.where("product_categoty = '[]'") #It returns the last record that we have just created.

    Hope this help!