Add blob value usage example + update tests

doc/guide.md

@@ -400,7 +400,7 @@ Here are the supported consistency and serial-consistency levels:
 (alia/execute session bst {:consistency :all})
 ```
 
-You can also set the consistency globaly at the cluster level via
+You can also set the consistency globally at the cluster level via
 `qbits.alia/cluster` options.
 
 #### Routing key
@@ -503,7 +503,7 @@ and this can be applied on streaming queries just fine as a result.
 
 Row generators allow you to control how Row values are accumulated
 into a single unit. By default alia will create one (transient) map
-per row, but you might like vectors intead, or you could want to apply
+per row, but you might like vectors instead, or you could want to apply
 some computation at this level, this is just what they enable.
 
 The default Generator is defined as follows:
@@ -565,3 +565,21 @@ You can have control over the query caching using
 can set its value to `qbits.hayt/->raw` if you prefer not to use query caching.
 The default uses `clojure.core.memoize` with a LU cache with a `:threshold`
 of 100.
+
+## `blob` data: `byte-array`s
+
+Cassandra `blob` columns can store Java `byte-array` data.
+
+Ex:
+
+```clojure
+(defn- update-byte-array!
+  [session id ^bytes ba]
+  (let [statement (alia/prepare session "INSERT into t (id, ba) VALUES (?, ?);")]
+    (alia/execute session statement {:values [id ba]})))
+```
+
+Notably, Alia returns the column data as a `java.nio.ByteBuffer`, but conversion back to a `byte-array` can be accomplished by calling `.array`:
+ - https://docs.oracle.com/javase/8/docs/api/java/nio/ByteBuffer.html#array--
+
+For a working example, see `blob-test` in: [../test/qbits/alia_test.clj](../test/qbits/alia_test.clj).

test/qbits/alia_test.clj

@@ -13,6 +13,8 @@
    [manifold.stream :as stream])
   (:import
    [java.time Instant]
+   [java.util UUID]
+   [java.nio ByteBuffer]
    [com.datastax.oss.driver.api.core.cql ExecutionInfo]
    [com.datastax.oss.driver.api.core.data UdtValue TupleValue]))
 
@@ -112,7 +114,9 @@
                     id int,
                     text varchar,
                     PRIMARY KEY (id)
-                  );"))
+                  );")
+
+  (alia/execute session "CREATE TABLE IF NOT EXISTS blobs (id uuid, data blob, PRIMARY KEY (id));"))
 
 (defn teardown-test-keyspace
   [session]
@@ -571,3 +575,16 @@
            (-> (try (alia/tuple-encoder *session* :invalid-col :invalid-type) (catch Exception e e))
                ex-data
                :type)))))
+
+(deftest blob-test
+  (testing "basic blob interactions"
+    (let [id (UUID/randomUUID)
+          bytes (byte-array (shuffle (range 256)))
+          insert-statement (alia/prepare *session* "INSERT INTO blobs (id, data) VALUES (?, ?);")]
+      (alia/execute *session* insert-statement {:values [id bytes]})
+      (let [row (->> (alia/execute *session* "SELECT * FROM blobs WHERE id = :id;"
+                         {:values {:id id}})
+                     (first))
+            ^ByteBuffer data (:data row)
+            row-bytes (.array data)]
+        (is (= (vec bytes) (vec row-bytes)))))))