如何将JSON对象转换为MySQL行？

Question

I'd like to take a JSON string representing an object from a 3rd party API and insert it into a MySQL table. The JSON object properties match the table fields 1-to-1. There are several hundred columns in this table/JSON object. And there will be a few dozen rows to insert at any time.

I'd rather not make a huge struct. But if I need to, then I'd rather not db.Prepare() an INSERT statement with several hundred "?"s. But if I have to then I'd rather not Have to write a stmt.Exec() with several hundred parameters.

Is there a good way to do this in golang? Or is it just going to be extremely inefficient?

Answer 1

Use the following given a slice of valid database field names fieldNames and JSON data data:

var j map[string]interface{}
if err := json.Unmarshal(data, &j); err != nil {
    // handle error
}
var names []string
var inserts []string
var values []interface{}
for _, n := range fieldNames {
    if v, ok := j[n]; ok {
        names = append(names, n)
        inserts = append(inserts, "?")
        values = append(values, v)
    }
}
statement := "insert into yourTable (" +
    strings.Join(names, ", ") +
    ") values (" + strings.Join(inserts, ", ") + ")"
err := db.Exec(statement, values...)

To avoid SQL injection attacks, it's important to work from a slice of known column names.

You can query the database to create the fieldNames slice. See Get table column names in MySQL? for the query required.

If the column names and JSON names are different, then replace the slice with a map where the keys are the column names and the values are the JSON names:

fieldNames := map[string]string{
  "column1": "json1",
  ... and so on
}

var j map[string]interface{}
if err := json.Unmarshal(data, &j); err != nil {
    // handle error
}
var names []string
var inserts []string
var values []interface{}
for dbName, jsonName := range fieldNames {
    if v, ok := j[jsonName]; ok {
        names = append(names, dbName)
        inserts = append(inserts, "?")
        values = append(values, v)
    }
}
statement := "insert into yourTable (" +
    strings.Join(names, ", ") +
    ") values (" + strings.Join(inserts, ", ") + ")"
err := db.Exec(statement, values...)