# `MishkaCmsMigration.Resources.Validations.SourceInstalled`
[🔗](https://github.com/mishka-group/mishka_cms_migration/blob/v0.0.1/lib/mishka_cms_migration/resources/__validations/source_installed.ex#L5)

Refuses a run whose `source` names no installed source plugin
(`MishkaCmsMigration.Source.fetch/1`), on its `source` field, so a run is never created for a
source no job could read.

    create :create do
      validate MishkaCmsMigration.Resources.Validations.SourceInstalled, before_action?: true
    end

Run it `before_action?`, after the input is cleaned.

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*Consult [api-reference.md](api-reference.md) for complete listing*