fix(schema-compiler): Allow escaping of curly braces in yaml models (#9469)

* fix(schema-compiler): Allow escaping of curly braces in yaml models

* add tests

* remove obsolete

* Add docs

---------

Co-authored-by: Igor Lukanin <[email protected]>

Author: KSDaemon

docs/pages/product/data-modeling/syntax.mdx

@@ -602,6 +602,73 @@ the [template context](/reference/python/cube#templatecontext-class).
 
 </ReferenceBox>
 
+### Curly braces and escaping
+
+As you can see in the examples above, within [SQL expressions][self-sql-expressions],
+curly braces are used to reference cubes and members.
+
+In YAML data models, use `{reference}`:
+
+```yaml
+cubes:
+  - name: orders
+    sql: >
+      SELECT id, created_at
+      FROM {other_cube.sql()}
+
+    dimensions:
+      - name: status
+        sql: status
+        type: string
+
+      - name: status_x2
+        sql: "{status} || ' ' || {status}"
+        type: string
+```
+
+In JavaScript data models, use `${reference}` in [JavaScript template
+literals][link-js-template-literals] (mind the dollar sign):
+
+```javascript
+cube(`orders`, {
+  sql: `
+    SELECT id, created_at
+    FROM ${other_cube.sql()}
+  `,
+
+  dimensions: {
+    status: {
+      sql: `status`,
+      type: `string`
+    },
+
+    status_x2: {
+      sql: `${status} || ' ' || ${status}`,
+      type: `string`
+    }
+  }
+})
+```
+
+If you need to use literal, non-referential curly braces in YAML, e.g.,
+to define a JSON object, you can escape them with a backslash:
+
+```yaml
+cubes:
+  - name: json_object_in_postgres
+    sql: SELECT CAST('\{"key":"value"\}'::JSON AS TEXT) AS json_column
+
+  - name: csv_from_s3_in_duckdb
+    sql: >
+      SELECT *
+      FROM read_csv(
+        's3://bbb/aaa.csv',
+        delim = ',',
+        header = true,
+        columns=\{'time':'DATE','count':'NUMERIC'\}
+      )
+```
+
 ### Non-SQL references
 
 Outside [SQL expressions][self-sql-expressions], `column` is not recognized
@@ -693,4 +760,5 @@ defining dynamic data models.
 [ref-custom-granularities]: /reference/data-model/dimensions#granularities
 [ref-style-guide]: /guides/style-guide
 [ref-polymorphism]: /product/data-modeling/concepts/polymorphic-cubes
-[ref-data-blending]: /product/data-modeling/concepts/data-blending
+[ref-data-blending]: /product/data-modeling/concepts/data-blending
+[link-js-template-literals]: https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Scripting/Strings#embedding_javascript

packages/cubejs-schema-compiler/src/compiler/YamlCompiler.ts

@@ -230,11 +230,11 @@ export class YamlCompiler {
       } else if (str[i] === '`' && peek().inStr) {
         result.push(str[i]);
         stateStack.pop();
-      } else if (str[i] === '{' && str[i + 1] === '{' && peek()?.inFormattedStr) {
-        result.push('{{');
+      } else if (str[i] === '\\' && str[i + 1] === '{' && stateStack.length === 0) {
+        result.push('\\{');
         i += 1;
-      } else if (str[i] === '}' && str[i + 1] === '}' && peek()?.inFormattedStr) {
-        result.push('}}');
+      } else if (str[i] === '\\' && str[i + 1] === '}' && stateStack.length === 0) {
+        result.push('\\}');
         i += 1;
       } else if (str[i] === '{' && peek()?.inFormattedStr) {
         result.push(str[i]);

packages/cubejs-schema-compiler/test/integration/postgres/yaml-compiler.test.ts

@@ -57,6 +57,40 @@ cubes:
     );
   });
 
+  it('simple with json/curly in sql', async () => {
+    const { compiler, joinGraph, cubeEvaluator } = prepareYamlCompiler(`
+cubes:
+  - name: ActiveUsers
+    sql: SELECT 1 as user_id, '2022-01-01'::TIMESTAMP as timestamp, CAST('\\{"key":"value"\\}'::JSON AS TEXT) AS json_col
+
+    dimensions:
+      - name: time
+        sql: "{CUBE}.timestamp"
+        type: time
+      - name: json_col
+        sql: json_col
+        type: string
+    `);
+    await compiler.compile();
+
+    const query = new PostgresQuery({ joinGraph, cubeEvaluator, compiler }, {
+      dimensions: ['ActiveUsers.time', 'ActiveUsers.json_col'],
+      timezone: 'UTC'
+    });
+
+    console.log(query.buildSqlAndParams());
+
+    const res = await dbRunner.testQuery(query.buildSqlAndParams());
+    console.log(JSON.stringify(res));
+
+    expect(res).toEqual(
+      [{
+        active_users__time: '2022-01-01T00:00:00.000Z',
+        active_users__json_col: '{"key":"value"}',
+      }]
+    );
+  });
+
   it('missed sql', async () => {
     const { compiler } = prepareYamlCompiler(`
 cubes: