Fetching CSV data using Golang

Question

As you can see below I have read the CSV file and also fetched data using the index. After that, I aligned the header name with its respective index.

Now, how can I fetch particular data from the CSV file using the header name and not the index? I'm new to Golang and programming.

    func main() {
    file, ferr := os.Open("company1.csv")
    if ferr != nil {
    panic(ferr)
    }
    reader := csv.NewReader(file)
    reader.Comma = '|'
    reader.Comma = ','
    records, _ := reader.ReadAll()

    fmt.Println(records) // prints all the records
    fmt.Println("\n",records[1][0]) //to print the first record
    fmt.Println("\n",records[0]) // header
    //to print the index along the header
    index := 0
    for _, x := range records[0] {
    fmt.Println("\n",x ,"-",index)
    index++
    }

There are some 3rd party libraries you may find helpful. One example: github.com/smartystreets/scanners And a walkthrough: smartystreets.com/blog/2018/01/csv-scanning-in-go — Brian Wagner
– Brian Wagner, Commented Dec 13, 2021 at 23:27

2 revs user13631587 · Accepted Answer · 2021-12-14 06:39:16Z

6

Create a map from header name to column index. Use that map when indexing a record:

fields := make(map[string]int)
for i, name := range records[0] {
    fields[name] = i
}

for _, record = range records[1:] {
    x = record[fields["name"]]
    fmt.Println(x)
}

The above code does not handle the case where an expected column is missing from the file. Add this check before looping through the data records:

for _, name := range []string{"name", "column2"} {
    if _, ok := fields[name]; !ok {
        log.Fatal("field missing", name)
    }
}

edited Dec 14, 2021 at 6:39

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2 revs
user13631587

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3 Comments

anvi Over a year ago

Thank you so much, but can u tell me how can I take the column name as user input, or make this process more dynamic.

user13631587 Over a year ago

There are many ways to get user input: command line flags, environment variables, read with the fmt or bufio package, etc. Once you the field name in a variable, let's call it field, you get that field from a record with record[fields[field].

Zach Young Over a year ago

@anvi, it looks like this is the answer for your question, please accept it so Penélope gets full credit.

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