Implement schema management proposal. Fixes #95.

This commit is contained in:
Richard Newman 2016-11-08 12:09:53 -08:00
parent 451f13a053
commit d568977fa9
3 changed files with 806 additions and 0 deletions

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;; This Source Code Form is subject to the terms of the Mozilla Public
;; License, v. 2.0. If a copy of the MPL was not distributed with this
;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
(ns datomish.schema-management
#?(:cljs
(:require-macros
[datomish.pair-chan :refer [go-pair <?? <?]]))
(:require
[clojure.data :refer [diff]]
#?@(:clj [[datomish.pair-chan :refer [go-pair <?? <?]]])
[clojure.set]
[datomish.api :as d]
[datomish.schema] ; For validation.
[datomish.util :as util
#?(:cljs :refer-macros :clj :refer) [raise raise-str cond-let]]))
;; For testing.
(def log (fn [& args]) #_ println)
;; This code implements the concept described in
;; https://github.com/mozilla/datomish/wiki/Proposal:-application-schema-coordination-and-versioning
;;
;; This is a high-level API: it's built on top of the schema alteration
;; primitives and plain ol' storage layer that Datomish exposes.
;;
;; Schema fragments are described by name and version number.
;; The existing schema in the store is diffed against incoming fragments.
;;
;; Validation:
;; - No attribute should be mentioned in a different fragment in the
;; store and the input. Attributes cannot move between fragments.
;; - Fragments with the same name and version should be congruent,
;; with the only acceptable changes being to add new attributes.
;; - Fragments with an increased version number can make changes to
;; attributes:
;; - Adding new attributes.
;; - Rename existing attributes.
;; - Altering cardinality, uniqueness, or indexing properties.
;;
;; The inputs to the diffing process are:
;; - The set of schema fragments.
;; - The existing database (and implicitly its active schema).
;; - A collection of attribute renames.
;; - A set of app- and fragment-scoped pre/post functions that will
;; be run before and after schema changes are applied.
;;
;; The output of the diffing process, if validation succeeds, is a
;; set of operations to perform on the knowledge base. If there are
;; no version changes, no pre/post functions will be included.
;;
;; Potential outcomes:
;; - An attribute is mentioned in two incoming fragments: error.
;; - An attribute is in fragment A in the store and fragment B in input: error.
;; - An attribute changed between the store and input, but the version number is the same: error.
;; - An attribute is present in input, but not the store, and the version number is the same: add the attribute.
;; - An attribute is present in the store, but not input, and the version number is the same: do nothing.
;; - A fragment's version number is higher in the store than in the input:
;; - If the input is a subset of the fragment in the store, then do nothing.
;; - If the input differs, then error.
;; - A fragment's version number is higher in the input than in the store:
;; - Run app 'pre' and 'post'.
;; - Run this fragment's 'pre' and 'post'.
;; - Alter the store to match. If altering fails due to a consistency error, roll back and error out.
;;
;; The core data format here, which we call a "managed schema fragment" is:
;;
;; {:name :org.mozilla.foo
;; :version 4
;; :attributes {:foo/bar {:db/valueType ...}}}
;;
;; This can be trivially expanded from the 'simple schema' format used by
;; JS callers:
;;
;; {"name": "org.mozilla.foo",
;; "version": 4,
;; "attributes": [
;; {"name": "foo/bar",
;; "type": ...}]}
;;
;; and it can be trivially collapsed into the format understood by the
;; transactor, which we call "schema datoms":
;;
;; [{:db/ident :org.mozilla.foo
;; :db.schema/version 4}
;; {:db/name :foo/bar
;; :db.schema/_attribute :org.mozilla.foo
;; :db/valueType ...}]
(defn- attribute->datoms [schema-fragment-id [attribute-name attribute-pairs]]
(let [attribute-id (d/id-literal :db.part/user)]
[(assoc
attribute-pairs
:db.install/_attribute :db.part/db
;; Point back to the fragment.
:db.schema/_attribute schema-fragment-id
:db/id attribute-id
:db/ident attribute-name)]))
(defn managed-schema-fragment->datoms [{:keys [name version attributes]}]
(let [fragment-id (d/id-literal :db.part/db)]
(conj
(mapcat (partial attribute->datoms fragment-id) attributes)
{:db/id fragment-id
:db/ident name
:db.schema/version version})))
(defn <collect-schema-fragment-versions
"Return a map, like {:org.mozilla.foo 5, :org.mozilla.core 2}."
[db]
(let [ident (partial d/ident db)]
(go-pair
(into {}
(map
(fn [[s v]] [(ident s) v])
(<?
(d/<q db '[:find ?s ?v
:in $
:where [?s :db.schema/version ?v]])))))))
(defn <collect-schema-fragment-attributes
"Return a map, like {:foo/name :org.mozilla.foo}.
Attributes that are not linked to a fragment will not be returned."
[db]
(let [ident (partial d/ident db)]
(go-pair
(into {}
(map
(fn [[a f]] [(ident a) (ident f)])
(<?
(d/<q db '[:find ?a ?f
:in $
:where [?f :db.schema/attribute ?a]])))))))
(defn db->symbolic-schema [db]
(:symbolic-schema db))
(defn changed-attribute->datoms [schema-fragment-id attribute-name existing new-values]
(let [differences (first (diff new-values existing))]
(when-not (empty? differences)
[(merge
{:db/id (d/id-literal :db.part/user)
:db/ident attribute-name
;; Point back to the fragment.
:db.schema/_attribute schema-fragment-id
:db.alter/_attribute :db.part/db}
differences)])))
(defn changed-schema-fragment->datoms [schema-fragment-id existing-schema name attributes version]
(conj
(mapcat (fn [[attribute-name new-values]]
(let [existing (get existing-schema attribute-name)]
(if existing
(changed-attribute->datoms
schema-fragment-id
attribute-name
existing
new-values)
(attribute->datoms
schema-fragment-id [attribute-name new-values]))))
attributes)
{:db.schema/version version
:db/ident name
:db/id (d/id-literal :db.part/db)}))
(defn- prepare-schema-application-for-fragments
"Given a non-empty collection of fragments known to be new or outdated,
yield a migration sequence containing the necessary pre/post ops and
transact bodies."
[db
symbolic-schema
schema-fragment-versions
schema-fragment-attributes
{:keys [fragments pre post fragment-pre fragment-post] :as args}]
(when-let
[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]])
[[:transact
(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]]))
;; 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)]]))
fragments)]
(concat
(when pre [[:call pre]])
body
(when post [[:call post]]))))
(defn- <prepare-schema-application*
[db {:keys [fragments pre post fragment-pre fragment-post] :as args}]
{:pre [(map? (first fragments))]}
(go-pair
(let [symbolic-schema (db->symbolic-schema db)
schema-fragment-versions (<? (<collect-schema-fragment-versions db))
schema-fragment-attributes (<? (<collect-schema-fragment-attributes db))]
;; Filter out any incoming fragments that are already present with
;; the correct version. Err if any of the fragments are outdated,
;; or contain attributes that are already present elsewhere.
(let [to-apply
(filter
(fn [{:keys [name version attributes]}]
{:pre [(not (nil? name))
(integer? version)
(not (empty? attributes))]}
;; Make sure that every attribute in this fragment is either
;; already associate with its ident, or not associated with
;; anything. We do this before we even check the version.
(doseq [attribute-name (keys attributes)]
(when-let [existing-fragment (get schema-fragment-attributes attribute-name)]
(when-not (= existing-fragment name)
(raise "Attribute " attribute-name
" already belongs to schema fragment "
existing-fragment ", not " name "."
{:error :schema/different-fragment
:existing existing-fragment
:fragment name}))))
;; Now we know that every attribute is either this fragment's or
;; not assigned to one.
;; Check our fragment version against the store.
(let [existing-version (get schema-fragment-versions name)]
(log "Schema" name "at existing version" existing-version)
(or (nil? existing-version)
(> version existing-version)
(when (< version existing-version)
(raise "Existing version of " name " is " existing-version
", which is later than requested " version "."
{:error :schema/outdated-version
:name name
:version version
:existing existing-version})))))
fragments)]
(if (empty? to-apply)
(do
(log "No fragments left to apply.")
nil)
(prepare-schema-application-for-fragments
db
symbolic-schema
schema-fragment-versions
schema-fragment-attributes
(assoc args :fragments to-apply)))))))
(defn <prepare-schema-application
"Take a database and a sequence of managed schema fragments,
along with migration tools, and return a migration operation."
[db {:keys [fragments pre post fragment-pre fragment-post] :as args}]
(when-not (contains? args :fragments)
(raise-str "Missing :fragments argument to <prepare-schema-application."))
(if (empty? fragments)
(go-pair nil)
(do
;; Validate each fragment.
(doseq [fragment fragments]
(datomish.schema/validate-schema (:attributes fragment)))
(let [repeated-attributes (util/repeated-keys (map :attributes fragments))]
(when-not (empty? repeated-attributes)
(raise "Attributes appear in more than one fragment: " repeated-attributes
{:error :schema/repeated-attributes
:repeated repeated-attributes}))
;; At this point we know we have schema fragments to apply,
;; and that they don't overlap. They might still cross fragment
;; boundaries when compared to the store, and they might still
;; be inconsistent, but we can proceed to the next step.
(<prepare-schema-application* db args)))))
(defn- <schema-fragment-versions-match?
"Quickly return true if every provided fragment matches the
version in the store."
[db fragments]
(go-pair
(let [schema-fragment-versions (<? (<collect-schema-fragment-versions db))]
(every?
(fn [{:keys [name version]}]
(= (get schema-fragment-versions name)
version))
fragments))))
(defn <apply-schema-alteration
"Take a database and a sequence of managed schema fragments,
along with migration tools, and transact a migration operation.
Throws and rolls back if any step of the operation fails. Returns
nil if no work was done, or the last db-report otherwise."
[conn args]
(go-pair
(if (or (empty? (:fragments args))
(<? (<schema-fragment-versions-match?
(d/db conn)
(:fragments args))))
(log "No schema work to do.")
;; Do the real fragment op computation inside the transaction.
;; This avoids a check-then-write race.
(<?
(d/<transact!
conn
(fn [db do-transact]
(go-pair
(let [last-report (atom {:db-after db})
ops (<? (<prepare-schema-application db args))]
(doseq [[op op-arg] ops]
(case op
:transact
(reset! last-report
(<? (do-transact
(:db-after @last-report)
op-arg)))
:call
;; We use <?? so that callers don't accidentally
;; break us if they pass a function that returns
;; nil rather than a *channel* that returns nil.
(when-let [new-report
(<?? (op-arg (:db-after @last-report)
do-transact))]
(when-not (:db-after new-report)
(raise "Function didn't return a valid report."
{:error :schema/invalid-report
:function op-arg
:returned new-report}))
(reset! last-report new-report))))
@last-report))))))))

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;; This Source Code Form is subject to the terms of the Mozilla Public
;; License, v. 2.0. If a copy of the MPL was not distributed with this
;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
(ns datomish.schema-management-test
#?(:cljs
(:require-macros
[datomish.pair-chan :refer [go-pair <?]]
[datomish.node-tempfile-macros :refer [with-tempfile]]
[cljs.core.async.macros :as a :refer [go]]))
(:require
[datomish.schema-management :as sm]
[datomish.api :as d]
#?@(:clj [[datomish.jdbc-sqlite]
[datomish.pair-chan :refer [go-pair <?]]
[tempfile.core :refer [tempfile with-tempfile]]
[datomish.test-macros :refer [deftest-async deftest-db]]
[clojure.test :as t :refer [is are deftest testing]]
[clojure.core.async :refer [go <! >!]]])
#?@(:cljs [[datomish.js-sqlite]
[datomish.pair-chan]
[datomish.test-macros :refer-macros [deftest-async deftest-db]]
[datomish.node-tempfile :refer [tempfile]]
[cljs.test :as t :refer-macros [is are deftest testing async]]
[cljs.core.async :as a :refer [<! >!]]]))
#?(:clj
(:import [clojure.lang ExceptionInfo]))
#?(:clj
(:import [datascript.db DB])))
#?(:cljs
(def Throwable js/Error))
(def id-schema (d/id-literal :db.part/db))
(def id-foobar (d/id-literal :db.part/user))
(def trivial-schema-managed-fragment-v1
{:name :com.example.foo
:version 1
:attributes
{:foo/bar
{:db/cardinality :db.cardinality/one
:db/valueType :db.type/string}}})
(def additional-schema-managed-fragment-v7
{:name :com.example.bar
:version 7
:attributes
{:bar/noo
{:db/cardinality :db.cardinality/one
:db/unique :db.unique/value
:db/valueType :db.type/long}}})
(def additional-schema-managed-fragment-v8
{:name :com.example.bar
:version 8
:attributes
{:bar/choo
{:db/cardinality :db.cardinality/many
:db/fulltext true
:db/valueType :db.type/string}
:bar/noo
{:db/cardinality :db.cardinality/one
:db/unique :db.unique/value
:db/valueType :db.type/long}}})
(def trivial-schema-managed-fragment-v2
{:name :com.example.foo
:version 2
:attributes
{:foo/bar
{:db/cardinality :db.cardinality/many
:db/valueType :db.type/string}}})
(def trivial-schema-v1
(sm/managed-schema-fragment->datoms trivial-schema-managed-fragment-v1))
;; TODO
(deftest test-managed-schema-fragment->datoms)
(defn <initialize-with-schema [conn schema]
(go-pair
(let [tx (<? (d/<transact! conn schema))]
(let [idents (map :db/ident schema)
db (d/db conn)]
(into {}
(map (fn [ident]
[ident (d/entid db ident)])
idents))))))
(deftest-db test-schema-management-downgrades conn
(is (empty? (<? (sm/<collect-schema-fragment-versions (d/db conn)))))
(testing "Downgrades cause errors."
(let [fragment {:name :com.a
:version 4
:attributes
{:foo/bar
{:db/cardinality :db.cardinality/one
:db/valueType :db.type/string}}}]
(<? (<initialize-with-schema
conn
(sm/managed-schema-fragment->datoms fragment)))
(let [current (<? (sm/<collect-schema-fragment-versions (d/db conn)))]
(is (= {:com.a 4} current)))
(is (thrown-with-msg?
Throwable
#"Existing version of :com.a is 4, which is later than requested 3"
(<?
(sm/<prepare-schema-application
(d/db conn)
{:fragments
[(assoc fragment :version 3)]})))))))
(deftest-db test-schema-management-conflicting-ownership conn
(is (empty? (<? (sm/<collect-schema-fragment-versions (d/db conn)))))
(testing "Conflicting managed fragments cause errors."
(is (thrown-with-msg?
Throwable #"Attributes appear in more than one"
(<? (sm/<prepare-schema-application
(d/db conn)
{:fragments
[{:name :com.a
:version 1
:attributes
{:foo/bar
{:db/cardinality :db.cardinality/one
:db/valueType :db.type/string}}}
{:name :com.b
:version 1
:attributes
{:foo/bar
{:db/cardinality :db.cardinality/one
:db/valueType :db.type/string}}}]}))))))
(defn- without-tempids
"Return the map without any k-v pairs for which v is a TempId."
[m]
(into {} (keep (fn [[k v]] (when-not (d/id-literal? v) [k v])) m)))
(defn- op-seq-without-tempids [ops]
(map (fn [[op val]]
(if (= op :transact)
[op (map without-tempids val)]
[op val]))
ops))
;; This is much more convenient than trying to make tempids match
;; in our tests.
(defn- =-op-seq-without-tempids
"Compare two sequences of operations (e.g., [[:call foo]])
without comparing TempIds within :transact operations."
[expected actual]
(= (op-seq-without-tempids expected)
(op-seq-without-tempids actual)))
;;;
;;; In this test we use simple strings to denote pre/post functions.
;;; That makes everything a little easier to test.
;;;
;;; Note carefully that we manually transact some schema fragments,
;;; then we use the schema management functions to get a _plan_. That's
;;; not the same as executing the plan.
;;;
(deftest-db test-schema-management conn
(is (empty? (<? (sm/<collect-schema-fragment-versions (d/db conn)))))
;; Start off with the trivial schema at v1.
(let [attrs (<? (<initialize-with-schema conn trivial-schema-v1))
db (d/db conn)]
(testing "We have a version, and it's 1. There are no other schemas."
(is (= {:com.example.foo 1}
(<? (sm/<collect-schema-fragment-versions db)))))
(testing "This schema fragment has one attribute."
(is (= {:foo/bar :com.example.foo}
(<? (sm/<collect-schema-fragment-attributes db)))))
(testing "The symbolic schema contains our attribute."
(is (= :db.type/string
(get-in (sm/db->symbolic-schema db)
[:foo/bar :db/valueType]))))
(testing "An empty fragment yields no work."
(is (nil? (<? (sm/<prepare-schema-application
db
{:pre "X"
:post "Y"
:fragments []})))))
(testing "The same fragment, expressed as a managed schema fragment, yields no work."
(is (nil? (<? (sm/<prepare-schema-application
db
{:fragments [trivial-schema-managed-fragment-v1]})))))
(testing "If we try to add a second fragment, we run all-pre, new fragment, all-post."
(is (=-op-seq-without-tempids
[[:call "X"]
[:transact (sm/managed-schema-fragment->datoms
additional-schema-managed-fragment-v7)]
[:call "Y"]]
(<? (sm/<prepare-schema-application
db
{:pre "X"
:post "Y"
:fragment-pre {}
:fragment-post {}
:fragments [additional-schema-managed-fragment-v7]})))))
(testing "If we upgrade one of the fragments, we run all-pre, the appropriate fragment pre, changed fragment, fragment post, all-post."
(is (=-op-seq-without-tempids
[[:call "X"]
[:call "A"]
[:transact
[{:db/ident :com.example.foo
:db.schema/version 2}
{:db/ident :foo/bar
:db.alter/_attribute :db.part/db
:db.schema/_attribute (d/entid db :com.example.foo)
:db/cardinality :db.cardinality/many}]]
[:call "B"]
[:call "Y"]]
(<? (sm/<prepare-schema-application
db
{:pre "X"
:post "Y"
:fragment-pre {:com.example.foo {1 "A"}}
:fragment-post {:com.example.foo {1 "B"}}
:fragments [trivial-schema-managed-fragment-v2]})))))
(testing "If we upgrade both, we run all-pre, each fragment pre, fragment, fragment post, all post."
(let [db (:db-after
(<?
(d/<transact! conn (sm/managed-schema-fragment->datoms
additional-schema-managed-fragment-v7))))
next-up
{:pre "XX"
:post "YY"
:fragment-pre {:com.example.foo {1 "AA"}}
:fragment-post {:com.example.foo {1 "BB"}
:com.example.bar {7 "CC"}}
:fragments [trivial-schema-managed-fragment-v2
additional-schema-managed-fragment-v8
]}
counter (atom 0)
pre (atom nil)
post (atom nil)
fragment-pre-foo (atom nil)
fragment-post-foo (atom nil)
fragment-post-bar (atom nil)
next-up-but-with-functions
{:pre (fn [db _]
(reset! pre (swap! counter inc))
nil)
:post (fn [db _]
(reset! post (swap! counter inc))
nil)
:fragment-pre {:com.example.foo
{1 (fn [db _]
(reset! fragment-pre-foo (swap! counter inc))
nil)}}
:fragment-post {:com.example.foo
{1 (fn [db _]
(reset! fragment-post-foo (swap! counter inc))
nil)}
:com.example.bar
{7 (fn [db _]
(reset! fragment-post-bar (swap! counter inc))
nil)}}
:fragments [trivial-schema-managed-fragment-v2
additional-schema-managed-fragment-v8]}]
(testing "Make sure our fragment was added correctly."
(let [bar (d/entid db :com.example.bar)]
(is (integer? bar))
(is (= :com.example.bar (d/ident db bar))))
(is (= {:com.example.foo 1
:com.example.bar 7}
(<? (sm/<collect-schema-fragment-versions db)))))
;; Now we'll see the addition of the new attribute, the
;; bump of both versions, and the change to foo.
(is (=-op-seq-without-tempids
[[:call "XX"]
[:call "AA"]
[:transact
[{:db/ident :com.example.foo
:db.schema/version 2}
{:db/ident :foo/bar
:db.alter/_attribute :db.part/db
:db.schema/_attribute (d/entid db :com.example.foo)
:db/cardinality :db.cardinality/many}]]
[:call "BB"]
[:transact
[{:db/ident :com.example.bar
:db.schema/version 8}
{:db/ident :bar/choo
:db.install/_attribute :db.part/db
:db.schema/_attribute (d/entid db :com.example.bar)
:db/fulltext true
:db/valueType :db.type/string
:db/cardinality :db.cardinality/many}]]
[:call "CC"]
[:call "YY"]]
(<? (sm/<prepare-schema-application
db
next-up))))
;; No change? Nothing to do.
(is (nil? (<? (sm/<apply-schema-alteration conn {:fragments []}))))
;; Now let's try the write!
(let [report (<? (sm/<apply-schema-alteration conn next-up-but-with-functions))
db (:db-after report)]
(is (not (nil? report)))
(testing "Things happened in the right order."
(is (= 1 @pre))
(is (= 2 @fragment-pre-foo))
(is (= 3 @fragment-post-foo))
(is (= 4 @fragment-post-bar))
(is (= 5 @post)))
(testing "Our changes were applied."
(is (= {:com.example.foo 2
:com.example.bar 8}
(<? (sm/<collect-schema-fragment-versions db))))
(is (= {:foo/bar :com.example.foo
:bar/choo :com.example.bar
:bar/noo :com.example.bar}
(<? (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.
db (atom (d/db conn))
v1-fragment
{:name :com.example.bar
:version 1
:attributes
{:bar/thoo
{:db/valueType :db.type/long
:db/cardinality :db.cardinality/many}
:bar/choo
{:db/cardinality :db.cardinality/one
:db/fulltext true
:db/valueType :db.type/string}}}
;; This is what we'll change the schema into.
v2-fragment
(assoc
(assoc-in v1-fragment [:attributes :bar/thoo :db/cardinality] :db.cardinality/one)
:version 2)
;; This is the migration we're going to test.
;; We're going to remove all existing :bar/thoo, and turn it into
;; cardinality one. We're going to make :bar/choo
;; unique, and we're going to use :bar/thoo to count the number of
;; chars in an entity's :bar/choo.
;; Note that the contents of the migration work:
;; - Look just like regular queries and transacts, except for
;; working with the internal API
;; - Don't have to transact the schema change at all.
migration
{:fragments [v2-fragment]
:pre (fn [db do-transact]
;; Retract all existing uses of :bar/thoo.
(go-pair
(<?
(do-transact
db
(map (fn [e]
[:db.fn/retractAttribute e :bar/thoo])
(<? (d/<q db '[:find [?e ...]
:in $
:where [?e :bar/thoo _]])))))))
:post (fn [db do-transact]
;; Transact some new use for :bar/thoo.
(go-pair
(<?
(do-transact
db
(map (fn [[e c]]
[:db/add e :bar/thoo (count c)])
(<? (d/<q db '[:find ?e ?c
:in $
:where [?e :bar/choo ?c]])))))))}]
;; We start empty.
(is (empty? (<? (sm/<collect-schema-fragment-versions @db))))
;; Apply the v1 schema.
(reset!
db
(:db-after
(<? (sm/<apply-schema-alteration
conn
{:fragments [v1-fragment]}))))
;; Make sure it's applied.
(testing "We can begin."
(is (= {:com.example.bar 1}
(<? (sm/<collect-schema-fragment-versions @db))))
(is (= {:bar/choo :com.example.bar
:bar/thoo :com.example.bar}
(<? (sm/<collect-schema-fragment-attributes @db)))))
;; Add some data.
(let [x (d/id-literal :db.part/user)
y (d/id-literal :db.part/user)]
(reset!
db
(:db-after
(<?
(d/<transact! conn [{:db/id x
:bar/thoo 99}
{:db/id y
:bar/thoo 88}
{:db/id x
:bar/choo "hello, world."}])))))
;; Alter the schema to v2, running our migration.
(reset! db (:db-after (<? (sm/<apply-schema-alteration conn migration))))
;; It worked!
(is (not (nil? @db)))
;; It persisted!
(is (= @db @(:current-db conn)))
(testing "The schema change applied."
(is (= :db.cardinality/one
(get-in (sm/db->symbolic-schema @db) [:bar/thoo :db/cardinality]))))
(is (= (count "hello, world.") ; 13.
(<? (d/<q @db
'[:find ?thoo .
:in $
:where
[?x :bar/choo "hello, world."]
[?x :bar/thoo ?thoo]]))))
;; Now that we changed its cardinality, we can transact another :bar/thoo
;; for the same entity, and we will get only the new value.
(let [x (<? (d/<q @db '[:find ?x . :in $ :where [?x :bar/choo "hello, world."]]))]
(is (= [13] (<? (d/<q @db [:find ['?thoo '...] :in '$ :where [x :bar/thoo '?thoo]]))))
(<? (d/<transact! conn [[:db/add x :bar/thoo 1492]]))
(is (= [1492] (<? (d/<q @db [:find ['?thoo '...] :in '$ :where [x :bar/thoo '?thoo]])))))))

View file

@ -3,6 +3,7 @@
[doo.runner :refer-macros [doo-tests doo-all-tests]]
[cljs.test :as t :refer-macros [is are deftest testing]]
datomish.schema-changes-test
datomish.schema-management-test
datomish.places.import-test
datomish.promise-sqlite-test
datomish.db-test
@ -19,6 +20,7 @@
(doo-tests
'datomish.schema-changes-test
'datomish.schema-management-test
'datomish.places.import-test
'datomish.promise-sqlite-test
'datomish.db-test