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implement watcher that gets trigged by db changes
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,57 @@ | ||
| package gomongo | ||
|
|
||
| import ( | ||
| "context" | ||
| "time" | ||
|
|
||
| "go.mongodb.org/mongo-driver/bson" | ||
| "go.mongodb.org/mongo-driver/mongo" | ||
| "go.mongodb.org/mongo-driver/mongo/options" | ||
| "golang.org/x/exp/slices" | ||
| ) | ||
|
|
||
| type namespace struct { | ||
| Database string `bson:"db"` | ||
| Collection string `bson:"coll"` | ||
| } | ||
|
|
||
| type updateDescription struct { | ||
| RemovedFields bson.A `bson:"removedFields"` | ||
| UpdatedFields bson.M `bson:"updatedFields"` | ||
| } | ||
|
|
||
| type event struct { | ||
| NS namespace `bson:"ns"` | ||
| ClusterTime time.Time `bson:"clusterTime"` | ||
| FullDocument bson.M `bson:"fullDocument"` | ||
| DocumentKey bson.M `bson:"documentKey"` | ||
| UpdateDescription updateDescription `bson:"updateDescription"` | ||
| OperationType string `bson:"operationType"` | ||
| } | ||
|
|
||
| func watch(ctx context.Context, mongoDatabase *mongo.Database, handleEvent func(ctx context.Context, e event) error, collectionNamesToWatch []string) error { | ||
| cs, err := mongoDatabase.Watch(ctx, mongo.Pipeline{}, options.ChangeStream().SetFullDocument(options.UpdateLookup)) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| defer cs.Close(ctx) | ||
| for cs.Next(ctx) { | ||
| var e event | ||
| if err := cs.Decode(&e); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| if collectionBellongToWatch(e.NS.Collection, collectionNamesToWatch) { | ||
| err := handleEvent(ctx, e) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| func collectionBellongToWatch(collectionName string, collections []string) bool { | ||
| return slices.Contains(collections, collectionName) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,32 @@ | ||
| package gomongo | ||
|
|
||
| import ( | ||
| "context" | ||
| "time" | ||
| ) | ||
|
|
||
| type History interface { | ||
| All(ctx context.Context) ([]Document, error) | ||
| Count(ctx context.Context) (int, error) | ||
| First(ctx context.Context) (Document, error) | ||
| Last(ctx context.Context) (Document, error) | ||
| Where(ctx context.Context, filter any) ([]Document, error) | ||
|
|
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| Drop(ctx context.Context) error | ||
|
|
||
| Name() string | ||
| } | ||
|
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| type Document struct { | ||
| CreatedAt time.Time | ||
| CollectionName string | ||
| ObjectID ID | ||
| Modified map[string]any | ||
| UpdatedFields map[string]UpdatedField | ||
| Action string | ||
| } | ||
|
|
||
| type UpdatedField struct { | ||
| Old any | ||
| New any | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,99 @@ | ||
| package gomongo | ||
|
|
||
| import ( | ||
| "context" | ||
| "errors" | ||
| "fmt" | ||
| "strings" | ||
|
|
||
| "github.com/r3labs/diff" | ||
| ) | ||
|
|
||
| type Watcher interface { | ||
| Watch(ctx context.Context, collections ...string) error | ||
| } | ||
|
|
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| type watcher struct { | ||
| database *Database | ||
| historyCollection *collection[Document] | ||
| } | ||
|
|
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| func NewWatcher(database *Database, historyCollectionName string) (Watcher, History, error) { | ||
| if err := validateDatabase(database); err != nil { | ||
| return nil, nil, err | ||
| } | ||
|
|
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| w := watcher{ | ||
| database: database, | ||
| historyCollection: &collection[Document]{database.mongoDatabase.Collection(historyCollectionName)}, | ||
| } | ||
|
|
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| return w, w.historyCollection, nil | ||
| } | ||
|
|
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| func (w watcher) Watch(ctx context.Context, collectionNamesToWatch ...string) error { | ||
| err := watch(ctx, w.database.mongoDatabase, w.handleEvents, collectionNamesToWatch) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| return nil | ||
| } | ||
|
|
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| func (w watcher) handleEvents(ctx context.Context, e event) error { | ||
| id, ok := e.DocumentKey["_id"].(ID) | ||
| if !ok { | ||
| return fmt.Errorf("could not get id from event document") | ||
| } | ||
|
|
||
| last, err := lastInsertedByObjectID(ctx, w.historyCollection, id) | ||
| if err != nil && err != ErrDocumentNotFound { | ||
| return fmt.Errorf("failed to get last entry") | ||
| } | ||
|
|
||
| updatedFields, err := updatedFields(last.Modified, e.FullDocument) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
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| doc := Document{ | ||
| CreatedAt: e.ClusterTime, | ||
| CollectionName: e.NS.Collection, | ||
| ObjectID: id, | ||
| Modified: e.FullDocument, | ||
| Action: e.OperationType, | ||
| UpdatedFields: updatedFields, | ||
| } | ||
|
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| _, err = w.historyCollection.Create(ctx, doc) | ||
| if err != nil && !errors.Is(err, ErrDuplicateKey) { | ||
| return err | ||
| } | ||
|
|
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| return nil | ||
| } | ||
|
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| func lastInsertedByObjectID[T any](ctx context.Context, c *collection[T], objectID ID) (T, error) { | ||
| filter := map[string]any{"objectid": objectID} | ||
| return c.LastInserted(ctx, filter) | ||
| } | ||
|
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| func updatedFields(last any, history any) (map[string]UpdatedField, error) { | ||
| changes, err := diff.Diff(last, history) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("failed to get diff between entries") | ||
| } | ||
|
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| updatedFields := make(map[string]UpdatedField, len(changes)) | ||
| for _, change := range changes { | ||
| field := strings.Join(change.Path, ".") | ||
| if field != "_id" { | ||
| updatedFields[field] = UpdatedField{ | ||
| Old: change.From, | ||
| New: change.To, | ||
| } | ||
| } | ||
| } | ||
|
|
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| return updatedFields, nil | ||
| } |