Export document to jsonFile one by one #131
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json.go
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| } | ||
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| return ioutil.WriteFile(exportPath, jsonString, os.ModePerm) | ||
| if _, err = f.WriteString("]"); err != nil { |
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When possible, like in this case, I prefer using the := operator
| err = db.ForEach(q, func(doc *d.Document) bool { | ||
| n++ | ||
| jsonByte, err := json.Marshal(doc.AsMap()) | ||
| if err != nil { |
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I think it would be a good idea to recover this error in the outer scope.
If there is any failure inside this function, then the export process would not report an error, but the result would be clearly not correct.
json.go
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| if n != collectionCount { | ||
| jsonString += "," | ||
| } | ||
| _, err = f.WriteString(jsonString) |
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I guess same thing for this error
ostafen
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ostafen
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Hey, @letterbeezps, first of all thank you for your contribution, you are doing a great job with the last PRs. The structure looks good, I only left some minor comments.
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| jsonString, err := json.Marshal(docs) | ||
| n := 0 | ||
| err = db.ForEach(q, func(doc *d.Document) bool { |
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The Count() and the ForEach() statements run in separate transactions. Thus, if new documents are inserted between them, the ForEach() statement will iterate a number of documents n > collectionCount, which would lead to some problem with the statement:
if n != collectionCount {
jsonString += ","
}
To prevent this issue, we can ensure the number of documents iterated by the ForEach() is exactly collectionCount using Limit():
err = db.ForEach(q.Limit(collectionCount), func(doc *d.Document) bool {
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You remind me that is can also cause problems when documents are deleted between them.
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I have a suggestion for ForEach() function, let consumer() return error instead of bool. If there is any failure inside this function, we can get the error info directly
func (db *DB) ForEach(q *query.Query, consumer func(_ *d.Document) error) error {
q, err := normalizeCriteria(q)
if err != nil {
return err
}
return db.IterateDocs(q, func(doc *d.Document) error {
if err := consumer(doc); err != nil {
return err
}
return nil
})
}
json.go
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| result, err := db.FindAll(query.NewQuery(collectionName)) | ||
| q := query.NewQuery(collectionName) | ||
| collectionCount, err := db.Count(q) |
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I would just call this variable count, for simplicity
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