70 lines
2.3 KiB
Go
70 lines
2.3 KiB
Go
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package wmo
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import (
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"go.mongodb.org/mongo-driver/bson"
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ct "gogs.mikescher.com/BlackForestBytes/goext/cursortoken"
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)
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func CreatePagination[TData any](coll *Coll[TData], token ct.CursorToken, fieldPrimary string, sortPrimary ct.SortDirection, fieldSecondary *string, sortSecondary *ct.SortDirection, pageSize *int) ([]bson.D, error) {
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cond := bson.A{}
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sort := bson.D{}
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valuePrimary, err := coll.getTokenValueAsMongoType(token.ValuePrimary, fieldPrimary)
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if err != nil {
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return nil, err
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}
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if sortPrimary == ct.SortASC {
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// We sort ASC on <field> - so we want all entries newer ($gt) than the $primary
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cond = append(cond, bson.M{fieldPrimary: bson.M{"$gt": valuePrimary}})
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sort = append(sort, bson.E{Key: fieldPrimary, Value: +1})
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} else if sortPrimary == ct.SortDESC {
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// We sort DESC on <field> - so we want all entries older ($lt) than the $primary
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cond = append(cond, bson.M{fieldPrimary: bson.M{"$lt": valuePrimary}})
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sort = append(sort, bson.E{Key: fieldPrimary, Value: -1})
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}
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if fieldSecondary != nil && sortSecondary != nil && *fieldSecondary != fieldPrimary {
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valueSecondary, err := coll.getTokenValueAsMongoType(token.ValueSecondary, *fieldSecondary)
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if err != nil {
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return nil, err
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}
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if *sortSecondary == ct.SortASC {
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// the conflict-resolution condition, for entries with the _same_ <field> as the $primary we take the ones with a greater $secondary (= newer)
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cond = append(cond, bson.M{"$and": bson.A{
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bson.M{fieldPrimary: valuePrimary},
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bson.M{*fieldSecondary: bson.M{"$gt": valueSecondary}},
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}})
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sort = append(sort, bson.E{Key: fieldPrimary, Value: +1})
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} else if *sortSecondary == ct.SortDESC {
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// the conflict-resolution condition, for entries with the _same_ <field> as the $primary we take the ones with a smaller $secondary (= older)
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cond = append(cond, bson.M{"$and": bson.A{
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bson.M{fieldPrimary: valuePrimary},
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bson.M{*fieldSecondary: bson.M{"$lt": valueSecondary}},
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}})
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sort = append(sort, bson.E{Key: fieldPrimary, Value: -1})
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}
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}
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pipeline := make([]bson.D, 0, 3)
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pipeline = append(pipeline, bson.D{{Key: "$match", Value: bson.M{"$or": cond}}})
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pipeline = append(pipeline, bson.D{{Key: "$sort", Value: sort}})
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if pageSize != nil {
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pipeline = append(pipeline, bson.D{{Key: "$limit", Value: int64(*pageSize + 1)}})
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}
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return pipeline, nil
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}
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