.get() method plus support for compound primary keys (#40)

* create_table now handles compound primary keys
* CLI now accepts multiple --pk for compound primary keys
* Docs for compound primary keys with CLI and Python library
* New .get() method plus documentation

Closes #36, closes #39

tests/test_cli.py

@@ -427,6 +427,31 @@ def test_insert_multiple_with_primary_key(db_path, tmpdir):
     assert ["id"] == db["dogs"].pks
 
 
+def test_insert_multiple_with_compound_primary_key(db_path, tmpdir):
+    json_path = str(tmpdir / "dogs.json")
+    dogs = [
+        {"breed": "mixed", "id": i, "name": "Cleo {}".format(i), "age": i + 3}
+        for i in range(1, 21)
+    ]
+    open(json_path, "w").write(json.dumps(dogs))
+    result = CliRunner().invoke(
+        cli.cli, ["insert", db_path, "dogs", json_path, "--pk", "id", "--pk", "breed"]
+    )
+    assert 0 == result.exit_code
+    db = Database(db_path)
+    assert dogs == db.execute_returning_dicts("select * from dogs order by breed, id")
+    assert {"breed", "id"} == set(db["dogs"].pks)
+    assert (
+        "CREATE TABLE [dogs] (\n"
+        "   [breed] TEXT,\n"
+        "   [id] INTEGER,\n"
+        "   [name] TEXT,\n"
+        "   [age] INTEGER,\n"
+        "   PRIMARY KEY ([id], [breed])\n"
+        ")"
+    ) == db["dogs"].schema
+
+
 def test_insert_not_null_default(db_path, tmpdir):
     json_path = str(tmpdir / "dogs.json")
     dogs = [

tests/test_create.py

@@ -55,6 +55,21 @@ def test_create_table(fresh_db):
     ) == table.schema
 
 
+def test_create_table_compound_primary_key(fresh_db):
+    table = fresh_db.create_table(
+        "test_table", {"id1": str, "id2": str, "value": int}, pk=("id1", "id2")
+    )
+    assert (
+        "CREATE TABLE [test_table] (\n"
+        "   [id1] TEXT,\n"
+        "   [id2] TEXT,\n"
+        "   [value] INTEGER,\n"
+        "   PRIMARY KEY ([id1], [id2])\n"
+        ")"
+    ) == table.schema
+    assert ["id1", "id2"] == table.pks
+
+
 def test_create_table_with_bad_defaults(fresh_db):
     with pytest.raises(AssertionError):
         fresh_db.create_table(
@@ -122,6 +137,13 @@ def test_create_table_from_example(fresh_db, example, expected_columns):
     ]
 
 
+def test_create_table_from_example_with_compound_primary_keys(fresh_db):
+    record = {"name": "Zhang", "group": "staff", "employee_id": 2}
+    table = fresh_db["people"].insert(record, pk=("group", "employee_id"))
+    assert ["group", "employee_id"] == table.pks
+    assert record == table.get(("staff", 2))
+
+
 def test_create_table_column_order(fresh_db):
     fresh_db["table"].insert(
         collections.OrderedDict(

tests/test_get.py

@@ -1,4 +1,34 @@
 import pytest
+from sqlite_utils.db import NotFoundError
+
+
+def test_get_rowid(fresh_db):
+    dogs = fresh_db["dogs"]
+    cleo = {"name": "Cleo", "age": 4}
+    row_id = dogs.insert(cleo).last_rowid
+    assert cleo == dogs.get(row_id)
+
+
+def test_get_primary_key(fresh_db):
+    dogs = fresh_db["dogs"]
+    cleo = {"name": "Cleo", "age": 4, "id": 5}
+    last_pk = dogs.insert(cleo, pk="id").last_pk
+    assert 5 == last_pk
+    assert cleo == dogs.get(5)
+
+
+@pytest.mark.parametrize(
+    "argument,expected_msg",
+    [(100, None), (None, None), ((1, 2), "Need 1 primary key value"), ("2", None)],
+)
+def test_get_not_found(argument, expected_msg, fresh_db):
+    fresh_db["dogs"].insert(
+        {"id": 1, "name": "Cleo", "age": 4, "is_good": True}, pk="id"
+    )
+    with pytest.raises(NotFoundError) as excinfo:
+        fresh_db["dogs"].get(argument)
+    if expected_msg is not None:
+        assert expected_msg == excinfo.value.args[0]
 
 
 @pytest.mark.parametrize(