31 lines
689 B
Go
31 lines
689 B
Go
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package mongoext
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import (
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"go.mongodb.org/mongo-driver/bson"
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"reflect"
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"strings"
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)
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// ProjectionFromStruct automatically generated a mongodb projection for a struct
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// This way you can pretty much always write
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// `options.FindOne().SetProjection(mongoutils.ProjectionFromStruct(...your_model...))`
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// to only get the data from mongodb that you will actually use in the later decode step
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func ProjectionFromStruct(obj interface{}) bson.M {
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v := reflect.ValueOf(obj)
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t := v.Type()
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result := bson.M{}
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for i := 0; i < v.NumField(); i++ {
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tag := t.Field(i).Tag.Get("bson")
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if tag == "" {
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continue
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}
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tag = strings.Split(tag, ",")[0]
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result[tag] = 1
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}
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return result
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}
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