'Rails migration, how to change the table column

I know that usually when we want to change one column of a table in the rails database. But now I want to make a big change to my projects table and sample table. What is the best way to achieve this? originally

projects table:
class CreateProjects < ActiveRecord::Migration[6.0]
  def change
    create_table :projects do |t|
      t.string :name
      t.string :project_id1
      t.string :project_id2
      t.text :curated_description
      t.integer :num_of_samples
      t.integer :num_of_runs
      t.integer :population
      t.text :related_publications
      t.text :original_description

      t.timestamps
    end
  end
end

Sample table:

class CreateSamples < ActiveRecord::Migration[6.0]
  def change
    create_table :samples do |t|
      t.string :sample_name
      t.string :project_name
      t.string :run_id
      t.string :second_run_id
      t.string :meta_project_id
      t.string :experiment_type
      t.string :nr_reads_sequenced
      t.string :instrument_model
      t.string :disease_phenotype
      t.string :is_disease_stage_available
      t.string :disease_stage
      t.text :more
      t.text :more_info
      t.string :country
      t.string :collection_date
      t.string :sex
      t.integer :host_age
      t.string :diet
      t.string :longitude
      t.string :lattitude
      t.float :BMI
      t.string :associated_phenotype
      t.string :QC_status
      t.text :recent_antibiotics_use
      t.text :antibiotics_used
      t.text :antibiotics_dose
      t.integer :days_without_antibiotics_use
      t.text :original_description
      t.text :curated_description
      t.references :project, null: false, foreign_key: true

      t.timestamps
    end
  end
end

And these two migration files are the earliest two files in my migrations files. At first, I want to drop these two files (also there is one join table related these two tables and I drop it as well), and I have already run the database migration to drop them. But when I want to create a new migration file using

rails generate migration createProjects

it tells me that there is a conflict because we have already have a file named xxx_creat_projects, and I do know that it is the earliest one I create, but I have already create the migration to drop the old tables, now how can I create a new projects and samples table. Or it is better if someone can tell me how to achieve this (make a big change to these tables because I must change a lot of columns). Thanks!

ruby-on-railsmigration


Solution 1:[1]

0

First, you need to create a migration file by running the command:

rails generate migration YourMigrationName

And then edit the migration file and add change method definition like this:

def change
  change_column :table_name, :column_name, :new_type
end

Sources

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Source: Stack Overflow

Solution Source
Solution 1

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