DAO Factory pattern for Issue #1270 #2105

rrreynaldo · 2022-10-17T12:46:57Z

…O Factory module

rrreynaldo · 2022-10-17T12:50:45Z

Hi @iluwatar, this is the implementation for the DAO Factory based on the following resources and it is my first issue; kindly inform me if there is incorrect logic/concept or things which could be improved. Thanks a lot!

burno1

I would only suggest to change that switch case statement, unless you have a fair position to have it like that

dao-factory/src/main/java/com/iluwatar/daofactory/DAOFactory.java

burno1

LGTM!

burno1 · 2022-10-17T13:42:20Z

Thank you, @rrreynaldo!

rrreynaldo · 2022-10-17T13:42:41Z

Hi @burno1, thanks for the review and I agree that enum would be a neater implementation. Just made the changes and Thanks a lot!

sonarqubecloud · 2022-10-17T14:00:29Z

Kudos, SonarCloud Quality Gate passed!

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burno1 · 2022-10-17T17:27:26Z

This closes #1270

burno1 · 2022-10-17T17:28:15Z

@rrreynaldo, add the issue to the description of the PR, so we can have the two linked

rrreynaldo · 2022-10-18T00:48:02Z

@burno1 Done!

iluwatar · 2022-10-24T17:13:47Z

dao-factory/README.md

+layout: pattern
+title: Data Access Object Factory (DAO Factory)
+folder: dao-factory
+permalink: /patterns/dao-factory/
+categories: Architectural
+language: en
+tags:
+ - Data access


Check out the updated yaml frontmatter requirements at https://github.com/iluwatar/java-design-patterns/wiki/01.-How-to-contribute. In essence, you can drop some of the tags here.

iluwatar · 2022-10-24T17:27:56Z

dao-factory/README.md

+
+DAO Factory is a design pattern which utilise the Abstract Factory and Factory Method to create and produce a new instance of DAOs that are needed by the client application by creating a concrete Factory for a specific data source type.
+
+## Explanation


If possible, please add here the standard items

real world example

in plain words

wikipedia (or some other authoritative source) says

iluwatar · 2022-10-24T17:31:48Z

dao-factory/pom.xml

+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>5.8.1</version>


Use the version from the parent pom.xml

iluwatar · 2022-10-24T17:32:37Z

dao-factory/src/main/java/com/iluwatar/daofactory/Account.java

+    public int getId() {
+        return id;
+    }


Use Lombok where possible to reduce boilerplate

iluwatar · 2022-10-24T17:33:23Z

dao-factory/src/main/java/com/iluwatar/daofactory/App.java

+/**
+ * An implementation example for a client code
+ */


Please explain the pattern briefly and how this example code implements it.

iluwatar · 2022-10-24T17:44:14Z

dao-factory/src/main/java/com/iluwatar/daofactory/PostgresDAOFactory.java

+    // Connection variable information to Postgres database
+    private static final String conn = "jdbc:postgresql://localhost:5432/dao_factory";
+    private static final String user = "postgres";
+    private static final String pass = "123";


If I understood correctly, running the example requires that a local PostgreSQL database server is running? Usually what we do is use an in-memory database (like H2) by default and then it's possible to configure the code to use an external database, but not required.

iluwatar · 2022-10-24T17:44:49Z

dao-factory/src/main/java/com/iluwatar/daofactory/PostgresDAOFactory.java

+            e.printStackTrace();
+            System.err.println(e.getClass().getName()+": "+e.getMessage());


Check this throughout the code

iluwatar · 2022-10-24T17:47:28Z

dao-factory/src/test/java/com.iluwatar.daofactory/PostgresOrderDAOTest.java

+    @Test
+    void testInsertOrder() {
+        Method method = null;
+        try {
+            method = PostgresOrderDAO.class.getMethod("insertOrder", String.class, String.class, String.class);
+        } catch (NoSuchMethodException e) {
+            e.printStackTrace();
+        }
+        assertNotNull(method);
+    }


I don't see much value in this kind of reflection-based tests

iluwatar · 2022-10-24T17:55:38Z

dao-factory/src/main/java/com/iluwatar/daofactory/PostgresOrderDAO.java

+        Order template = new Order();
+        Connection con = PostgresDAOFactory.createConnection();
+        Statement stmt;
+        ResultSet rs;
+        String sql = "SELECT * FROM orders WHERE (";
+        boolean firstCondition = true;
+
+        // Combining the query with the variable value depending on the
+        // attribute that has been passed to the function
+        if (senderName == null && rcvrName == null && destination == null) {
+            return template;
+        }
+        // Combining the senderName attribute
+        if (senderName != null && !senderName.equals("")) {
+            senderName = "'" + senderName + "'";
+            sql += "sender_name = " +senderName;
+            firstCondition = false;
+        }
+        // Combining the receiverName attribute
+        if (rcvrName != null && !rcvrName.equals("")) {
+            rcvrName = "'" + rcvrName + "'";
+            if (firstCondition) {
+                sql += "receiver_name = " + rcvrName;
+                firstCondition = false;
+            } else {
+                sql += " AND receiver_name = " + rcvrName;
+            }
+        }
+        // Combining the destination attribute
+        if (destination != null && !destination.equals("")) {
+            destination = "'" + destination + "'";
+            if (firstCondition) {
+                sql += "destination = " + destination;
+            } else {
+                sql += " AND destination = " + destination;
+            }
+        }
+        // Closing the sql statement
+        sql += ");";


General note about this kind of SQL query building using string concatenation

High risk of SQL injection if you accidentally concatenate user input to your SQL queries

Difficult to avoid syntax errors in non-trivial cases, when dynamic SQL gets more complex

I would recommend using JPA criteria queries or jOOQ to make the code cleaner and safer.

iluwatar · 2022-10-24T17:56:16Z

dao-factory/src/main/java/com/iluwatar/daofactory/DataSourceType.java

+public enum DataSourceType {
+    POSTGRES    // And other data source type
+}


We could have here another data source H2

stale · 2022-11-23T18:31:16Z

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

iluwatar · 2022-12-01T16:46:04Z

Closed due to inactivity

rrreynaldo and others added 9 commits October 15, 2022 22:17

Implementation draft for DAO Factory; Setting up configuration for DA…

bc02a43

…O Factory module

Added implementation example and reconfigure package and dependencies

2f4244f

Update Implementation sample in App; Reconfigure maven pom config

1a46790

Refactoring code; Add puml diagram

2203496

Refactor package name;

d357bc2

Added tests for main source code

1018723

Updates class diagram

b05041e

Added README for the design pattern

f70c89d

Merge branch 'iluwatar:master' into master

636d80f

burno1 suggested changes Oct 17, 2022

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dao-factory/src/main/java/com/iluwatar/daofactory/DAOFactory.java Outdated Show resolved Hide resolved

dao-factory/src/main/java/com/iluwatar/daofactory/DAOFactory.java Outdated Show resolved Hide resolved

rrreynaldo added 2 commits October 18, 2022 00:38

Added enum for Data Source Type and reconfigure changes to enum;

a09e478

Merge remote-tracking branch 'origin/master'

9362d67

burno1 approved these changes Oct 17, 2022

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iluwatar requested changes Oct 24, 2022

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iluwatar self-assigned this Oct 24, 2022

iluwatar added the status: under review label Oct 24, 2022

stale bot added the status: stale issues and pull requests that have not had recent interaction label Nov 23, 2022

iluwatar closed this Dec 1, 2022

iluwatar added this to the 1.26.0 milestone Dec 1, 2022


		DAO Factory is a design pattern which utilise the Abstract Factory and Factory Method to create and produce a new instance of DAOs that are needed by the client application by creating a concrete Factory for a specific data source type.

		## Explanation

		e.printStackTrace();
		System.err.println(e.getClass().getName()+": "+e.getMessage());

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DAO Factory pattern for Issue #1270 #2105

DAO Factory pattern for Issue #1270 #2105

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burno1 commented Oct 17, 2022

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iluwatar commented Dec 1, 2022

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rrreynaldo commented Oct 17, 2022 •

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