Nikita Tokarchuk
4 years ago
parent
cf23c3b579
commit
7f46008227
@ -1,162 +0,0 @@ |
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package common |
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|
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import ( |
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"fmt" |
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"reflect" |
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"strconv" |
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"strings" |
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|
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"go.mongodb.org/mongo-driver/bson/primitive" |
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"go.mongodb.org/mongo-driver/mongo" |
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"go.mongodb.org/mongo-driver/mongo/options" |
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"github.com/mainnika/mongox-go-driver/v2/mongox" |
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"github.com/mainnika/mongox-go-driver/v2/mongox/query" |
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) |
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func createSimpleLoad(db mongox.Database, target interface{}, composed *query.Query) (cursor *mongo.Cursor, err error) { |
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collection := db.GetCollectionOf(target) |
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opts := options.Find() |
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opts.Sort = composed.Sorter() |
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opts.Limit = composed.Limiter() |
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opts.Skip = composed.Skipper() |
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return collection.Find(db.Context(), composed.M(), opts) |
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} |
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func createAggregateLoad(db mongox.Database, target interface{}, composed *query.Query) (cursor *mongo.Cursor, err error) { |
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collection := db.GetCollectionOf(target) |
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opts := options.Aggregate() |
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pipeline := primitive.A{} |
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if !composed.Empty() { |
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pipeline = append(pipeline, primitive.M{"$match": primitive.M{"$expr": composed.M()}}) |
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} |
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if composed.Sorter() != nil { |
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pipeline = append(pipeline, primitive.M{"$sort": composed.Sorter()}) |
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} |
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if composed.Skipper() != nil { |
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pipeline = append(pipeline, primitive.M{"$skip": *composed.Skipper()}) |
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} |
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if composed.Limiter() != nil { |
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pipeline = append(pipeline, primitive.M{"$limit": *composed.Limiter()}) |
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} |
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el := reflect.ValueOf(target).Elem() |
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elType := el.Type() |
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numField := elType.NumField() |
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_, preloads := composed.Preloader() |
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for i := 0; i < numField; i++ { |
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field := elType.Field(i) |
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tag := field.Tag |
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preloadTag, ok := tag.Lookup("preload") |
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if !ok { |
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continue |
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} |
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jsonTag, ok := tag.Lookup("json") |
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if jsonTag == "-" { |
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return nil, fmt.Errorf("preload private field is impossible") |
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} |
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jsonData := strings.SplitN(jsonTag, ",", 2) |
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jsonName := field.Name |
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if len(jsonData) > 0 { |
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jsonName = strings.TrimSpace(jsonData[0]) |
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} |
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preloadData := strings.Split(preloadTag, ",") |
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if len(preloadData) == 0 { |
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continue |
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} |
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if len(preloadData) == 1 { |
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panic("there is no foreign field") |
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} |
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localField := strings.TrimSpace(preloadData[0]) |
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if len(localField) == 0 { |
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localField = "_id" |
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} |
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foreignField := strings.TrimSpace(preloadData[1]) |
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if len(foreignField) == 0 { |
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panic("there is no foreign field") |
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} |
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preloadLimiter := 100 |
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preloadReversed := false |
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if len(preloadData) > 2 { |
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stringLimit := strings.TrimSpace(preloadData[2]) |
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intLimit := preloadLimiter |
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preloadReversed = strings.HasPrefix(stringLimit, "-") |
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if preloadReversed { |
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stringLimit = stringLimit[1:] |
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} |
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intLimit, err = strconv.Atoi(stringLimit) |
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if err == nil { |
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preloadLimiter = intLimit |
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} |
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} |
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for _, preload := range preloads { |
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if preload != jsonName { |
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continue |
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} |
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isSlice := el.Field(i).Kind() == reflect.Slice |
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typ := el.Field(i).Type() |
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if typ.Kind() == reflect.Slice { |
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typ = typ.Elem() |
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} |
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if typ.Kind() != reflect.Ptr { |
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panic("preload field should have ptr type") |
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} |
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lookupCollection := db.GetCollectionOf(reflect.Zero(typ).Interface()) |
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lookupVars := primitive.M{"selector": "$" + localField} |
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lookupPipeline := primitive.A{ |
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primitive.M{"$match": primitive.M{"$expr": primitive.M{"$eq": primitive.A{"$" + foreignField, "$$selector"}}}}, |
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} |
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if preloadReversed { |
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lookupPipeline = append(lookupPipeline, primitive.M{"$sort": primitive.M{"_id": -1}}) |
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} |
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if isSlice && preloadLimiter > 0 { |
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lookupPipeline = append(lookupPipeline, primitive.M{"$limit": preloadLimiter}) |
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} else if !isSlice { |
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lookupPipeline = append(lookupPipeline, primitive.M{"$limit": 1}) |
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} |
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pipeline = append(pipeline, primitive.M{ |
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"$lookup": primitive.M{ |
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"from": lookupCollection.Name(), |
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"let": lookupVars, |
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"pipeline": lookupPipeline, |
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"as": jsonName, |
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}, |
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}) |
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if isSlice { |
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continue |
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} |
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pipeline = append(pipeline, primitive.M{ |
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"$unwind": primitive.M{ |
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"preserveNullAndEmptyArrays": true, |
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"path": "$" + jsonName, |
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}, |
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}) |
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} |
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} |
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return collection.Aggregate(db.Context(), pipeline, opts) |
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} |
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@ -0,0 +1,33 @@ |
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package database |
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import ( |
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"fmt" |
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"go.mongodb.org/mongo-driver/mongo" |
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"github.com/mainnika/mongox-go-driver/v2/mongox" |
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"github.com/mainnika/mongox-go-driver/v2/mongox/query" |
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) |
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// LoadStream function loads documents one by one into a target channel
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func (d *Database) LoadStream(target interface{}, filters ...interface{}) (mongox.StreamLoader, error) { |
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var cursor *mongo.Cursor |
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var err error |
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composed := query.Compose(filters...) |
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hasPreloader, _ := composed.Preloader() |
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if hasPreloader { |
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cursor, err = d.createAggregateLoad(target, composed) |
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} else { |
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cursor, err = d.createSimpleLoad(target, composed) |
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} |
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if err != nil { |
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return nil, fmt.Errorf("can't create find result: %w", err) |
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} |
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l := &StreamLoader{Cursor: cursor, ctx: d.Context(), target: target} |
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return l, nil |
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} |
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