Class: Parse::Schema::Migration

Inherits:
Object
  • Object
show all
Defined in:
lib/parse/schema.rb

Overview

Represents a schema migration to be applied.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(model_class, diff, client: nil) ⇒ Migration

Returns a new instance of Migration.



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# File 'lib/parse/schema.rb', line 387

def initialize(model_class, diff, client: nil)
  @model_class = model_class
  @diff = diff
  @client = client || Parse.client
end

Instance Attribute Details

#client ⇒ Object (readonly)

Returns the value of attribute client.



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# File 'lib/parse/schema.rb', line 385

def client
  @client
end

#diff ⇒ Object (readonly)

Returns the value of attribute diff.



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# File 'lib/parse/schema.rb', line 385

def diff
  @diff
end

#model_class ⇒ Object (readonly)

Returns the value of attribute model_class.



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# File 'lib/parse/schema.rb', line 385

def model_class
  @model_class
end

Instance Method Details

#apply!(dry_run: false) ⇒ Hash

Apply the migration to the server.

Parameters:

  • dry_run (Boolean) (defaults to: false) —

    if true, only preview without applying

Returns:

  • (Hash) —

    results of the migration



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# File 'lib/parse/schema.rb', line 447

def apply!(dry_run: false)
  return { status: :skipped, message: "No migration needed" } unless needed?

  if dry_run
    return { status: :preview, operations: operations, preview: preview }
  end

  results = { status: :success, applied: [], errors: [] }

  # Create class if needed
  unless @diff.server_exists?
    schema = build_schema
    response = @client.create_schema(@model_class.parse_class, schema)
    if response.success?
      results[:applied] << { action: :create_class, class_name: @model_class.parse_class }
    else
      results[:errors] << { action: :create_class, error: response.error }
      results[:status] = :partial
    end
    return results
  end

  # Add missing fields
  @diff.missing_on_server.each do |name, type|
    field_name = @model_class.field_map[name].to_s
    field_schema = { "fields" => { field_name => field_definition(type) } }

    response = @client.update_schema(@model_class.parse_class, field_schema)
    if response.success?
      results[:applied] << { action: :add_field, field: field_name, type: type }
    else
      results[:errors] << { action: :add_field, field: field_name, error: response.error }
      results[:status] = :partial
    end
  end

  results[:status] = :failed if results[:applied].empty? && results[:errors].any?
  results
end

#needed? ⇒ Boolean

Check if migration is needed.

A migration is needed when the class does not yet exist on the server, or when the server does not already cover every locally-defined field. Defined in terms of the one-way SchemaDiff#server_covers_local? rather than the strict bidirectional SchemaDiff#in_sync? so that a server which is a strict superset of the local model (extra server-only columns the migrator would never add) does not report a "needed" migration with zero operations.

Returns:

  • (Boolean) 


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# File 'lib/parse/schema.rb', line 403

def needed?
  !@diff.server_exists? || !@diff.server_covers_local?
end

#operations ⇒ Array<Hash>

Get the operations that would be performed.

Returns:



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# File 'lib/parse/schema.rb', line 409

def operations
  ops = []

  unless @diff.server_exists?
    ops << { action: :create_class, class_name: @model_class.parse_class }
  end

  @diff.missing_on_server.each do |name, type|
    ops << {
      action: :add_field,
      field: @model_class.field_map[name].to_s,
      type: REVERSE_TYPE_MAP[type] || "String",
    }
  end

  ops
end

#preview ⇒ String

Preview the migration without applying.

Returns:

  • (String) —

    human-readable preview



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# File 'lib/parse/schema.rb', line 429

def preview
  return "No migration needed" unless needed?

  lines = ["Migration for #{@model_class.parse_class}:"]
  operations.each do |op|
    case op[:action]
    when :create_class
      lines << "  CREATE CLASS #{op[:class_name]}"
    when :add_field
      lines << "  ADD FIELD #{op[:field]} (#{op[:type]})"
    end
  end
  lines.join("\n")
end