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Add database backend for data storage
Signed-off-by: Knut Ahlers <knut@ahlers.me>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,106 @@ | ||
| package database | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "database/sql" | ||
| "embed" | ||
| "encoding/json" | ||
| "regexp" | ||
| "strings" | ||
|
|
||
| "github.com/jmoiron/sqlx" | ||
| "github.com/pkg/errors" | ||
| ) | ||
|
|
||
| type ( | ||
| connector struct { | ||
| db *sqlx.DB | ||
| } | ||
| ) | ||
|
|
||
| var ( | ||
| // ErrCoreMetaNotFound is the error thrown when reading a non-existent | ||
| // core_meta key | ||
| ErrCoreMetaNotFound = errors.New("core meta entry not found") | ||
|
|
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| //go:embed schema/** | ||
| schema embed.FS | ||
|
|
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| migrationFilename = regexp.MustCompile(`^([0-9]+)\.sql$`) | ||
| ) | ||
|
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| // New creates a new Connector with the given driver and database | ||
| func New(driverName, dataSourceName string) (Connector, error) { | ||
| db, err := sqlx.Connect(driverName, dataSourceName) | ||
| if err != nil { | ||
| return nil, errors.Wrap(err, "connecting database") | ||
| } | ||
|
|
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| conn := &connector{db: db} | ||
| return conn, errors.Wrap(conn.applyCoreSchema(), "applying core schema") | ||
| } | ||
|
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| func (c connector) Close() error { | ||
| return errors.Wrap(c.db.Close(), "closing database") | ||
| } | ||
|
|
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| func (c connector) DB() *sqlx.DB { | ||
| return c.db | ||
| } | ||
|
|
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| // ReadCoreMeta reads an entry of the core_meta table specified by | ||
| // the given `key` and unmarshals it into the `value`. The value must | ||
| // be a valid variable to `json.NewDecoder(...).Decode(value)` | ||
| // (pointer to struct, string, int, ...). In case the key does not | ||
| // exist a check to 'errors.Is(err, sql.ErrNoRows)' will succeed | ||
| func (c connector) ReadCoreMeta(key string, value any) error { | ||
| var data struct{ Key, Value string } | ||
| data.Key = key | ||
|
|
||
| if err := c.db.Get(&data, "SELECT * FROM core_meta WHERE key = $1", data.Key); err != nil { | ||
| if errors.Is(err, sql.ErrNoRows) { | ||
| return ErrCoreMetaNotFound | ||
| } | ||
| return errors.Wrap(err, "querying core meta table") | ||
| } | ||
|
|
||
| if data.Value == "" { | ||
| return errors.New("empty value returned") | ||
| } | ||
|
|
||
| if err := json.NewDecoder(strings.NewReader(data.Value)).Decode(value); err != nil { | ||
| return errors.Wrap(err, "JSON decoding value") | ||
| } | ||
|
|
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| return nil | ||
| } | ||
|
|
||
| // StoreCoreMeta stores an entry to the core_meta table soecified by | ||
| // the given `key`. The value given must be a valid variable to | ||
| // `json.NewEncoder(...).Encode(value)`. | ||
| func (c connector) StoreCoreMeta(key string, value any) error { | ||
| buf := new(bytes.Buffer) | ||
| if err := json.NewEncoder(buf).Encode(value); err != nil { | ||
| return errors.Wrap(err, "JSON encoding value") | ||
| } | ||
|
|
||
| _, err := c.db.NamedExec( | ||
| "INSERT INTO core_meta (key, value) VALUES (:key, :value) ON CONFLICT DO UPDATE SET value=excluded.value;", | ||
| map[string]any{ | ||
| "key": key, | ||
| "value": buf.String(), | ||
| }, | ||
| ) | ||
|
|
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| return errors.Wrap(err, "upserting core meta value") | ||
| } | ||
|
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| func (c connector) applyCoreSchema() error { | ||
| coreSQL, err := schema.ReadFile("schema/core.sql") | ||
| if err != nil { | ||
| return errors.Wrap(err, "reading core.sql content") | ||
| } | ||
|
|
||
| _, err = c.db.Exec(string(coreSQL)) | ||
| return errors.Wrap(err, "applying core schema") | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,62 @@ | ||
| package database | ||
|
|
||
| import ( | ||
| "testing" | ||
|
|
||
| "github.com/pkg/errors" | ||
| ) | ||
|
|
||
| func TestNewConnector(t *testing.T) { | ||
| dbc, err := New("sqlite", ":memory:") | ||
| if err != nil { | ||
| t.Fatalf("creating database connector: %s", err) | ||
| } | ||
| defer dbc.Close() | ||
|
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| row := dbc.DB().QueryRow("SELECT count(1) AS tables FROM sqlite_master WHERE type='table' AND name='core_meta';") | ||
|
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| var count int | ||
| if err = row.Scan(&count); err != nil { | ||
| t.Fatalf("reading table count result") | ||
| } | ||
|
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| if count != 1 { | ||
| t.Errorf("expected to find one result, got %d in count of core_meta table", count) | ||
| } | ||
| } | ||
|
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| func TestCoreMetaRoundtrip(t *testing.T) { | ||
| dbc, err := New("sqlite", ":memory:") | ||
| if err != nil { | ||
| t.Fatalf("creating database connector: %s", err) | ||
| } | ||
| defer dbc.Close() | ||
|
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||
| var ( | ||
| arbitrary struct{ A string } | ||
| testKey = "arbitrary" | ||
| ) | ||
|
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| if err = dbc.ReadCoreMeta(testKey, &arbitrary); !errors.Is(err, ErrCoreMetaNotFound) { | ||
| t.Error("expected core_meta not to contain key after init") | ||
| } | ||
|
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| checkWriteRead := func(testString string) { | ||
| arbitrary.A = testString | ||
| if err = dbc.StoreCoreMeta(testKey, arbitrary); err != nil { | ||
| t.Errorf("storing core_meta: %s", err) | ||
| } | ||
|
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| arbitrary.A = "" // Clear to test unmarshal | ||
| if err = dbc.ReadCoreMeta(testKey, &arbitrary); err != nil { | ||
| t.Errorf("reading core_meta: %s", err) | ||
| } | ||
|
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| if arbitrary.A != testString { | ||
| t.Errorf("expected meta entry to have %q, got %q", testString, arbitrary.A) | ||
| } | ||
| } | ||
|
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| checkWriteRead("just a string") // Turn one: Init from not existing | ||
| checkWriteRead("another random string") // Turn two: Overwrite | ||
| } |
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