array_type_field_filter: Add new contains filter to search on Array type field

README.md

@@ -45,7 +45,7 @@ const config = {
 
 <details><summary markdown="span"><strong>For LoopBack 3 users</strong></summary>
 
-Use the [Data source generator](http://loopback.io/doc/en/lb3/Data-source-generator.html) to add a PostgreSQL data source to your application.  
+Use the [Data source generator](http://loopback.io/doc/en/lb3/Data-source-generator.html) to add a PostgreSQL data source to your application.
 The generator will prompt for the database server hostname, port, and other settings
 required to connect to a PostgreSQL database. It will also run the `npm install` command above for you.
 
@@ -96,7 +96,7 @@ const config = {
 
 Check out [node-pg-pool](https://github.com/brianc/node-pg-pool) and [node postgres pooling example](https://github.com/brianc/node-postgres#pooling-example) for more information.
 
-### Properties
+### Configuration options
 
 <table>
   <thead>
@@ -106,7 +106,7 @@ Check out [node-pg-pool](https://github.com/brianc/node-pg-pool) and [node postg
       <th>Description</th>
     </tr>
   </thead>
-    <tbody>    
+    <tbody>
     <tr>
       <td>connector</td>
       <td>String</td>
@@ -176,6 +176,14 @@ Check out [node-pg-pool](https://github.com/brianc/node-pg-pool) and [node postg
       <td>Boolean/String</td>
       <td>Set to <code>false</code> to disable default sorting on <code>id</code> column(s). Set to <code>numericIdOnly</code> to only apply to IDs with a number type <code>id</code>.</td>
     </tr>
+    <tr>
+      <td>allowExtendedOperators</td>
+      <td>Boolean</td>
+      <td>Set to <code>true</code> to enable PostgreSQL-specific operators
+          such as <code>contains</code>. Learn more in
+          <a href="#extended-operators">Extended operators</a> below.
+      </td>
+    </tr>
   </tbody>
 </table>
 
@@ -272,7 +280,7 @@ The model definition consists of the following properties.
       <th>Description</th>
     </tr>
   </thead>
-  <tbody>    
+  <tbody>
     <tr>
       <td>name</td>
       <td>Camel-case of the database table name</td>
@@ -412,6 +420,12 @@ details on LoopBack's data types.
         VARCHAR2<br/>
         Default length is 1024
       </td>
+    </tr>
+     <tr>
+      <td>String[]</td>
+      <td>
+        VARCHAR2[]
+      </td>
     </tr>
     <tr>
       <td>Number</td>
@@ -531,14 +545,65 @@ CustomerRepository.find({
 });
 ```
 
+## Extended operators
+
+PostgreSQL supports the following PostgreSQL-specific operators:
+
+- [`contains`](#operator-contains)
+
+Please note extended operators are disabled by default, you must enable
+them at datasource level or model level by setting `allowExtendedOperators` to
+`true`.
+
+### Operator `contains`
+
+The `contains` operator allow you to query array properties and pick only
+rows where the stored value contains all of the items specified by the query.
+
+The operator is implemented using PostgreSQL [array operator
+`@>`](https://www.postgresql.org/docs/current/functions-array.html).
+
+**Note** The fields you are querying must be setup to use the postgresql array data type - see [Defining models](#defining-models) above.
+
+Assuming a model such as this:
+
+```ts
+@model({
+  settings: {
+    allowExtendedOperators: true,
+  }
+})
+class Post {
+  @property({
+    type: ['string'],
+    postgresql: {
+      dataType: 'varchar[]',
+    },
+  })
+  categories?: string[];
+}
+```
+
+You can query the tags fields as follows:
+
+```ts
+const posts = await postRepository.find({
+  where: {
+    {
+      categories: {'contains': ['AA']},
+    }
+  }
+});
+```
+
 ## Discovery and auto-migration
 
 ### Model discovery
 
 The PostgreSQL connector supports _model discovery_ that enables you to create LoopBack models
 based on an existing database schema. Once you defined your datasource:
--  LoopBack 4 users could use the commend [`lb4 discover`](https://loopback.io/doc/en/lb4/Discovering-models.html) to discover models. 
-- For LB3 users, please check [Discovering models from relational databases](https://loopback.io/doc/en/lb3/Discovering-models-from-relational-databases.html). 
+-  LoopBack 4 users could use the commend [`lb4 discover`](https://loopback.io/doc/en/lb4/Discovering-models.html) to discover models.
+- For LB3 users, please check [Discovering models from relational databases](https://loopback.io/doc/en/lb3/Discovering-models-from-relational-databases.html).
 
 (See [database discovery API](http://apidocs.strongloop.com/loopback-datasource-juggler/#datasource-prototype-discoverandbuildmodels) for related APIs information)
 
@@ -612,7 +677,7 @@ Here are some limitations and tips:
 
 ### Auto-migrate/Auto-update models with foreign keys
 
-Foreign key constraints can be defined in the model definition. 
+Foreign key constraints can be defined in the model definition.
 
 **Note**: The order of table creation is important. A referenced table must exist before creating a foreign key constraint.
 

lib/postgresql.js

@@ -522,6 +522,9 @@ PostgreSQL.prototype.buildExpression = function(columnName, operator,
       const regexOperator = operatorValue.ignoreCase ? ' ~* ?' : ' ~ ?';
       return new ParameterizedSQL(columnName + regexOperator,
         [operatorValue.source]);
+    case 'contains':
+      return new ParameterizedSQL(columnName + ' @> array[' + operatorValue.map((v) => `'${v}'`) + ']::'
+        + propertyDefinition.postgresql.dataType);
     default:
       // invoke the base implementation of `buildExpression`
       return this.invokeSuper('buildExpression', columnName, operator,

test/postgresql.test.js

@@ -73,7 +73,7 @@ describe('postgresql connector', function() {
           dataType: 'varchar[]',
         },
       },
-    });
+    }, {allowExtendedOperators: true});
     created = new Date();
   });
 
@@ -218,7 +218,7 @@ describe('postgresql connector', function() {
         post.should.have.property('tags');
         post.tags.should.be.Array();
         post.tags.length.should.eql(2);
-        post.tags.should.eql(['AA', 'AB']);
+        post.tags.toArray().should.eql(['AA', 'AB']);
         return Post.updateAll({where: {id: postId}}, {tags: ['AA', 'AC']});
       })
       .then(()=> {
@@ -228,7 +228,7 @@ describe('postgresql connector', function() {
         post.should.have.property('tags');
         post.tags.should.be.Array();
         post.tags.length.should.eql(2);
-        post.tags.should.eql(['AA', 'AC']);
+        post.tags.toArray().should.eql(['AA', 'AC']);
         done();
       })
       .catch((error) => {
@@ -245,7 +245,7 @@ describe('postgresql connector', function() {
         post.should.have.property('categories');
         post.categories.should.be.Array();
         post.categories.length.should.eql(2);
-        post.categories.should.eql(['AA', 'AB']);
+        post.categories.toArray().should.eql(['AA', 'AB']);
         return Post.updateAll({where: {id: postId}}, {categories: ['AA', 'AC']});
       })
       .then(()=> {
@@ -255,14 +255,32 @@ describe('postgresql connector', function() {
         post.should.have.property('categories');
         post.categories.should.be.Array();
         post.categories.length.should.eql(2);
-        post.categories.should.eql(['AA', 'AC']);
+        post.categories.toArray().should.eql(['AA', 'AC']);
         done();
       })
       .catch((error) => {
         done(error);
       });
   });
 
+  it('should support where filter for array type field', async () => {
+    await Post.create({
+      title: 'LoopBack Participates in Hacktoberfest',
+      categories: ['LoopBack', 'Announcements'],
+    });
+    await Post.create({
+      title: 'Growing LoopBack Community',
+      categories: ['LoopBack', 'Community'],
+    });
+
+    const found = await Post.find({where: {and: [
+      {
+        categories: {'contains': ['LoopBack', 'Community']},
+      },
+    ]}});
+    found.map(p => p.title).should.deepEqual(['Growing LoopBack Community']);
+  });
+
   it('should support boolean types with false value', function(done) {
     Post.create(
       {title: 'T2', content: 'C2', approved: false, created: created},