Add retweet queries

persistence/retweet_queries.go

@@ -0,0 +1,49 @@
+package persistence
+
+import (
+	"time"
+
+	"offline_twitter/scraper"
+)
+
+/**
+ * Save a Retweet.  Do nothing if it already exists, because none of its parameters are modifiable.
+ */
+func (p Profile) SaveRetweet(r scraper.Retweet) error {
+	_, err := p.DB.Exec(`
+			insert into retweets (retweet_id, tweet_id, retweeted_by, retweeted_at)
+			values (?, ?, ?, ?)
+			    on conflict do nothing
+		`,
+		r.RetweetID, r.TweetID, r.RetweetedByID, r.RetweetedAt.Unix(),
+	)
+	return err
+}
+
+
+/**
+ * Retrieve a Retweet by ID
+ */
+func (p Profile) GetRetweetById(id scraper.TweetID) (scraper.Retweet, error) {
+	stmt, err := p.DB.Prepare(`
+		select retweet_id, tweet_id, retweeted_by, retweeted_at
+		  from retweets
+		 where retweet_id = ?
+	`)
+	if err != nil {
+		return scraper.Retweet{}, err
+	}
+	defer stmt.Close()
+
+	var r scraper.Retweet
+	var retweeted_at int
+
+	row := stmt.QueryRow(id)
+	err = row.Scan(&r.RetweetID, &r.TweetID, &r.RetweetedByID, &retweeted_at)
+	if err != nil {
+		return scraper.Retweet{}, err
+	}
+
+	r.RetweetedAt = time.Unix(int64(retweeted_at), 0)
+	return r, nil
+}

persistence/retweet_queries_test.go

@@ -0,0 +1,37 @@
+package persistence_test
+
+import (
+	"testing"
+
+	"github.com/go-test/deep"
+)
+
+
+func TestSaveAndLoadRetweet(t *testing.T) {
+	profile_path := "test_profiles/TestRetweetQueries"
+	profile := create_or_load_profile(profile_path)
+
+	tweet := create_dummy_tweet()
+    err := profile.SaveTweet(tweet)
+    if err != nil {
+        t.Fatalf("Failed to save the tweet: %s", err.Error())
+    }
+
+    rt := create_dummy_retweet(tweet.ID)
+
+    // Save the Retweet
+    err = profile.SaveRetweet(rt)
+    if err != nil {
+    	t.Fatalf("Failed to save the retweet: %s", err.Error())
+    }
+
+    // Reload the Retweet
+    new_rt, err := profile.GetRetweetById(rt.RetweetID)
+    if err != nil {
+    	t.Fatalf("Failed to load the retweet: %s", err.Error())
+    }
+
+    if diff := deep.Equal(rt, new_rt); diff != nil {
+    	t.Error(diff)
+    }
+}

persistence/schema.sql

@@ -44,7 +44,7 @@ create table tweets (rowid integer primary key,
 );
 
 create table retweets(rowid integer primary key,
-    retweet_id integer not null,
+    retweet_id integer not null unique,
     tweet_id integer not null,
     retweeted_by integer not null,
     retweeted_at integer not null,

persistence/utils_test.go

@@ -26,6 +26,10 @@ func create_or_load_profile(profile_path string) persistence.Profile {
 			panic(err)
 		}
 		err = profile.SaveTweet(create_stable_tweet())
+		if err != nil {
+			panic(err)
+		}
+		err = profile.SaveRetweet(create_stable_retweet())
 	} else {
 		profile, err = persistence.LoadProfile(profile_path)
 	}
@@ -114,6 +118,18 @@ func create_stable_tweet() scraper.Tweet {
 	}
 }
 
+/**
+ * Create a stable retweet with a fixed ID and parameters
+ */
+func create_stable_retweet() scraper.Retweet {
+	retweet_id := scraper.TweetID(-1)
+	return scraper.Retweet{
+		RetweetID: retweet_id,
+		TweetID: -1,
+		RetweetedByID: -1,
+		RetweetedAt: time.Unix(20000000, 0),
+	}
+}
 
 /**
  * Create a new user with a random ID and handle
@@ -173,3 +189,18 @@ func create_dummy_tweet() scraper.Tweet {
 		Hashtags: []string{"hash1", "hash2"},
 	}
 }
+
+/**
+ * Create a new retweet with a random ID for a given TweetID
+ */
+func create_dummy_retweet(tweet_id scraper.TweetID) scraper.Retweet {
+	rand.Seed(time.Now().UnixNano())
+	retweet_id := scraper.TweetID(rand.Int())
+
+	return scraper.Retweet{
+		RetweetID: retweet_id,
+		TweetID: tweet_id,
+		RetweetedByID: -1,
+		RetweetedAt: time.Unix(20000000, 0),
+	}
+}