orm: improve the README and the tests. Add an error message for foreign key tags (#15670)

vlib/orm/README.md

@@ -17,6 +17,7 @@
 - `[sql: 'name']` sets a custom column name for the field
 - `[sql_type: 'SQL TYPE']` sets the sql type which is used in sql
 - `[default: 'sql defaults']` sets the default value or function when create a new table
+- `[fkey: 'parent_id']` sets foreign key for an field which holds an array
 
 ## Usage
 
@@ -27,7 +28,15 @@ struct Foo {
     created_at  time.Time   [sql_type: 'DATETIME']
     updated_at  string      [sql_type: 'DATETIME']
     deleted_at  time.Time
+    children    []Child     [fkey: 'parent_id']
 }
+
+struct Child {
+    id        int    [primary; sql: serial]
+    parent_id int
+    name      string
+}
+
 ```
 
 ### Create
@@ -54,6 +63,14 @@ var := Foo{
     created_at: time.now()
     updated_at: time.now().str()
     deleted_at: time.now()
+    children: [
+        Child{
+            name: 'abc'
+        },
+        Child{
+            name: 'def'
+        },
+    ]
 }
 
 sql db {
@@ -65,7 +82,7 @@ sql db {
 
 ```v ignore
 sql db {
-    update Foo set name = 'cde' where name == 'abc'
+    update Foo set name = 'cde', updated_at = time.now() where name == 'abc'
 }
 ```
 
@@ -84,7 +101,7 @@ result := sql db {
 ```
 ```v ignore
 result := sql db {
-    select from Foo where id > 1 limit 5
+    select from Foo where id > 1 && name != 'lasanha' limit 5
 }
 ```
 ```v ignore

vlib/orm/orm.v

@@ -383,7 +383,6 @@ pub fn orm_table_gen(table string, q string, defaults bool, def_unique_len int,
 		mut is_unique := false
 		mut is_skip := false
 		mut unique_len := 0
-		// mut fkey := ''
 		mut field_name := sql_field_name(field)
 		mut ctyp := sql_from_v(sql_field_type(field)) or {
 			field_name = '${field_name}_id'
@@ -427,14 +426,6 @@ pub fn orm_table_gen(table string, q string, defaults bool, def_unique_len int,
 						default_val = attr.arg
 					}
 				}
-				/*'fkey' {
-					if attr.arg != '' {
-						if attr.kind == .string {
-							fkey = attr.arg
-							continue
-						}
-					}
-				}*/
 				else {}
 			}
 		}

vlib/v/gen/c/sql.v

@@ -157,8 +157,12 @@ fn (mut g Gen) sql_insert(node ast.SqlStmtLine, expr string, table_name string,
 		} else if sym.kind == .array {
 			mut f_key := ''
 			for attr in f.attrs {
-				if attr.name == 'fkey' && attr.has_arg && attr.kind == .string {
-					f_key = attr.arg
+				if attr.name == 'fkey' && attr.has_arg {
+					if attr.kind == .string {
+						f_key = attr.arg
+					} else {
+						verror("fkey attribute need be string. Try [fkey: '$attr.arg'] instead of [fkey: $attr.arg]")
+					}
 				}
 			}
 			if f_key == '' {
@@ -714,8 +718,12 @@ fn (mut g Gen) sql_select(node ast.SqlExpr, expr string, left string, or_expr as
 			} else if sym.kind == .array {
 				mut fkey := ''
 				for attr in field.attrs {
-					if attr.name == 'fkey' && attr.has_arg && attr.kind == .string {
-						fkey = attr.arg
+					if attr.name == 'fkey' && attr.has_arg {
+						if attr.kind == .string {
+							fkey = attr.arg
+						} else {
+							verror("fkey attribute need be string. Try [fkey: '$attr.arg'] instead of [fkey: $attr.arg]")
+						}
 					}
 				}
 				if fkey == '' {

vlib/v/tests/orm_sub_array_struct_test.v

@@ -1,12 +1,12 @@
 import sqlite
 
 struct Parent {
-	id      int      [primary; sql: serial]
-	name    string
-	chields []Chield [fkey: 'parent_id']
+	id       int     [primary; sql: serial]
+	name     string
+	children []Child [fkey: 'parent_id']
 }
 
-struct Chield {
+struct Child {
 	id        int    [primary; sql: serial]
 	parent_id int
 	name      string
@@ -20,11 +20,11 @@ fn test_orm_array() {
 
 	par := Parent{
 		name: 'test'
-		chields: [
-			Chield{
+		children: [
+			Child{
 				name: 'abc'
 			},
-			Chield{
+			Child{
 				name: 'def'
 			},
 		]
@@ -43,7 +43,7 @@ fn test_orm_array() {
 	}
 
 	assert parent.name == par.name
-	assert parent.chields.len == par.chields.len
-	assert parent.chields[0].name == 'abc'
-	assert parent.chields[1].name == 'def'
+	assert parent.children.len == par.children.len
+	assert parent.children[0].name == 'abc'
+	assert parent.children[1].name == 'def'
 }