[nongnu] elpa/emacsql 99a8069389 135/427: Add support for foreign keys.

[ELPA Syncer]

branch: elpa/emacsql
commit 99a806938913afcfc30ea85f7b172659257c7d32
Author: Christopher Wellons <wellons@nullprogram.com>
Commit: Christopher Wellons <wellons@nullprogram.com>

    Add support for foreign keys.
---
 emacsql-tests.el |  4 ++++
 emacsql.el       | 23 ++++++++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/emacsql-tests.el b/emacsql-tests.el
index 5277eb0629..8eb8113805 100644
--- a/emacsql-tests.el
+++ b/emacsql-tests.el
@@ -104,6 +104,10 @@
      "CREATE TABLE foo (a, b, c, UNIQUE (a, b, c));")
     ([:create-table foo ([a b] :check (< a b)) ] '()
      "CREATE TABLE foo (a, b, CHECK (a < b));")
+    ([:create-table foo
+      ([a b c] :foreign ([a b] bar [aa bb] :on-delete :cascade))] '()
+      (concat "CREATE TABLE foo (a, b, c, FOREIGN KEY (a, b) "
+              "REFERENCES bar (aa, bb) ON DELETE CASCADE);"))
     ;; Drop table
     ([:drop-table $1] '(foo)
      "DROP TABLE foo;")))
diff --git a/emacsql.el b/emacsql.el
index 60c65a1a3d..a1986e2e19 100644
--- a/emacsql.el
+++ b/emacsql.el
@@ -438,6 +438,26 @@ definitions for return from a `emacsql-defexpander'."
              collect (combine (emacsql--column-to-string column)) into parts
              finally (cl-return (mapconcat #'identity parts ", ")))))
 
+(defun emacsql--foreign-key (spec)
+  (emacsql-with-vars "FOREIGN KEY "
+    (cl-destructuring-bind (child table parent . actions) (cl-coerce spec 
'list)
+      (mapconcat
+       #'identity
+       (cons
+        (format "(%s) REFERENCES %s (%s)" (idents child) (var table 
:identifier)
+                (idents parent))
+        (cl-loop for (key value) on actions by #'cddr collect
+                 (cl-ecase key
+                   (:on-update "ON UPDATE")
+                   (:on-delete "ON DELETE"))
+                 collect
+                 (cl-ecase value
+                   (:restrict "RESTRICT")
+                   (:set-nil "SET NULL")
+                   (:set-default "SET DEFAULT")
+                   (:cascade "CASCADE"))))
+       " "))))
+
 (defun emacsql--schema-to-string (schema)
   (cl-etypecase schema
     (vector (emacsql--columns-to-string schema))
@@ -451,7 +471,8 @@ definitions for return from a `emacsql-defexpander'."
                   (cl-ecase key
                     (:primary (format "PRIMARY KEY (%s)" (idents value)))
                     (:unique (format "UNIQUE (%s)" (idents value)))
-                    (:check (format "CHECK (%s)" (expr value))))))
+                    (:check (format "CHECK (%s)" (expr value)))
+                    (:foreign (combine (emacsql--foreign-key value))))))
         ", ")))))
 
 (defun emacsql--vector (vector)