feat: link and unlink document to resource model

packages/server/src/models/Document.ts

@@ -3,7 +3,7 @@ import TenantModel from 'models/TenantModel';
 import ModelSetting from './ModelSetting';
 import ModelSearchable from './ModelSearchable';
 
-export default class Attachment extends mixin(TenantModel, [
+export default class Document extends mixin(TenantModel, [
   ModelSetting,
   ModelSearchable,
 ]) {

packages/server/src/models/DocumentLink.ts

@@ -0,0 +1,44 @@
+import { Model, mixin } from 'objection';
+import TenantModel from 'models/TenantModel';
+import ModelSetting from './ModelSetting';
+import ModelSearchable from './ModelSearchable';
+
+export default class DocumentLink extends mixin(TenantModel, [
+  ModelSetting,
+  ModelSearchable,
+]) {
+  /**
+   * Table name
+   */
+  static get tableName() {
+    return 'document_links';
+  }
+
+  /**
+   * Model timestamps.
+   */
+  get timestamps() {
+    return ['createdAt', 'updatedAt'];
+  }
+
+  /**
+   * Relationship mapping.
+   */
+  static get relationMappings() {
+    const Document = require('models/Document');
+
+    return {
+      /**
+       * Sale invoice associated entries.
+       */
+      document: {
+        relation: Model.HasOneRelation,
+        modelClass: Document.default,
+        join: {
+          from: 'document_links.documentId',
+          to: 'documents.id',
+        },
+      },
+    };
+  }
+}

packages/server/src/models/SaleInvoice.ts

@@ -410,6 +410,7 @@ export default class SaleInvoice extends mixin(TenantModel, [
     const Branch = require('models/Branch');
     const Account = require('models/Account');
     const TaxRateTransaction = require('models/TaxRateTransaction');
+    const DocumentLink = require('models/DocumentLink');
 
     return {
       /**
@@ -523,6 +524,21 @@ export default class SaleInvoice extends mixin(TenantModel, [
           builder.where('reference_type', 'SaleInvoice');
         },
       },
+
+      /**
+       * Invoice may has many attachments.
+       */
+      attachments: {
+        relation: Model.HasManyRelation,
+        modelClass: DocumentLink.default,
+        join: {
+          from: 'sales_invoices.id',
+          to: 'document_links.modelId',
+        },
+        filter: (builder) => {
+          builder.where('modelRef', 'SaleInvoice');
+        },
+      },
     };
   }