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Add a :none migration for schema management. Fixes #113. r=grisha

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This allows for code to run before and after a schema fragment is
added for the first time.

The anticipated use for this is twofold:

1. To do initial setup, e.g., defining global entities.
2. To 'adopt' unmanaged attributes already defined in the store.

This 'pre' would manually alter or retract attributes so that the
transact of the new schema datoms can complete.

For example, if properties :foo/bar and :foo/baz will be unchanged,
but :noo/zob needs to change from a string to an integer, the :none
pre-function can alter the ident, and the :none post-function can
migrate and clean up.
This commit is contained in:
Richard Newman 2016-11-18 15:27:42 -08:00
parent 7784834fb3
commit 103a86f440
2 changed files with 77 additions and 18 deletions
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41
src/common/datomish/schema_management.cljc
View file

@ -183,29 +183,36 @@
[body
(mapcat
(fn [{:keys [name version attributes] :as fragment}]
(if-let [existing-version (get schema-fragment-versions name)]
;; It's a change.
;; Spit out any pre/post for this fragment, with a
;; transact of the datoms to effect the change and
;; bump the schema fragment version in the middle.
(concat
(when-let [fragment-pre-for-this
(get-in fragment-pre [name existing-version])]
[[:call fragment-pre-for-this]])
(let [existing-version (get schema-fragment-versions name)
datoms
[[:transact
(changed-schema-fragment->datoms (d/entid db name)
(if existing-version
;; It's a change.
;; Transact the datoms to effect the change and
;; bump the schema fragment version.
(changed-schema-fragment->datoms
(d/entid db name)
symbolic-schema
name
attributes
version)]]
(when-let [fragment-post-for-this
(get-in fragment-post [name existing-version])]
[[:call fragment-post-for-this]]))
version)
;; It's new! Just do it.
;; There can't be any fragment pre/post, 'cos there's no previous
;; version to come from.
[[:transact (managed-schema-fragment->datoms fragment)]]))
(managed-schema-fragment->datoms fragment))]]]
;; We optionally allow you to provide a `:none` migration here, which
;; is useful in the case where a vocabulary might have been added
;; outside of the schema management system.
(concat
(when-let [fragment-pre-for-this
(get-in fragment-pre [name (or existing-version :none)])]
[[:call fragment-pre-for-this]])
datoms
(when-let [fragment-post-for-this
(get-in fragment-post [name (or existing-version :none)])]
[[:call fragment-post-for-this]]))))
fragments)]
(concat

52
test/datomish/schema_management_test.cljc
View file

@ -342,6 +342,58 @@
:bar/noo :com.example.bar}
(<? (sm/<collect-schema-fragment-attributes db))))))))))
(deftest-db test-none-migration conn
(testing "A fragment that's never existed in the DB triggers :none pre and post."
(let [db (atom (d/db conn))
v1-fragment
{:name :com.example.foo
:version 1
:attributes
{:foo/bar
{:db/valueType :db.type/long
:db/cardinality :db.cardinality/many}}}
fail-called (atom nil)
pre-called (atom nil)
post-called (atom nil)
v1-migration
{:fragments [v1-fragment]
:fragment-pre {:com.example.foo
{:none (fn [db _]
(reset! pre-called true)
nil)
1 (fn [db _]
(reset! fail-called true)
nil)}}
:fragment-post {:com.example.foo
{:none (fn [db _]
(reset! post-called true)
nil)
1 (fn [db _]
(reset! fail-called true)
nil)}}}]
(is (empty? (<? (sm/<collect-schema-fragment-versions @db))))
;; Apply the v1 schema.
(reset!
db
(:db-after
(<? (sm/<apply-schema-alteration
conn
v1-migration))))
(is @pre-called)
(is @post-called)
(is (not @fail-called))
(is (= {:com.example.foo 1}
(<? (sm/<collect-schema-fragment-versions @db))))
(is (= {:foo/bar :com.example.foo}
(<? (sm/<collect-schema-fragment-attributes @db)))))))
(deftest-db test-functions-can-do-work conn
(let
[;; Use an atom to keep this long test fairly flat.