Convert every value of a dataframe - scala

Question

I need to modify the values of every column of a dataframe so that, they all are enclosed within double quotes after mapping but the dataframe still retains its original structure with the headers.
I tried mapping the values by changing the rows to sequences but it loses its headers in the output dataframe.
With this read in as input dataframe:
|prodid|name |city|
+------+-------+----+
|1 |Harshit|VNS |
|2 |Mohit |BLR |
|2 |Mohit |RAO |
|2 |Mohit |BTR |
|3 |Rohit |BOM |
|4 |Shobhit|KLK |
I tried the following code.
val columns = df.columns
df.map{ row =>
row.toSeq.map{col => "\""+col+"\"" }
}.toDF(columns:_*)
But it throws an error stating there's only 1 header i.e value in the mapped dataframe.
This is the actual result (if I remove ".df(columns:_*)"):
| value|
+--------------------+
|["1", "Harshit", ...|
|["2", "Mohit", "B...|
|["2", "Mohit", "R...|
|["2", "Mohit", "B...|
|["3", "Rohit", "B...|
|["4", "Shobhit", ...|
+--------------------+
And my expected result is something like:
|prodid|name |city |
+------+---------+------+
|"1" |"Harshit"|"VNS" |
|"2" |"Mohit" |"BLR" |
|"2" |"Mohit" |"RAO" |
|"2" |"Mohit" |"BTR" |
|"3" |"Rohit" |"BOM" |
|"4" |"Shobhit"|"KLK" |
Note: There are only 3 headers in this example but my original data has a lot of headers so manually typing each and every one of them is not an option in case the file header changes. How do I get this modified value dataframe from that?
Edit: If I need the quotes on all values except the Integers. So, the output is something like:
|prodid|name |city |
+------+---------+------+
|1 |"Harshit"|"VNS" |
|2 |"Mohit" |"BLR" |
|2 |"Mohit" |"RAO" |
|2 |"Mohit" |"BTR" |
|3 |"Rohit" |"BOM" |
|4 |"Shobhit"|"KLK" |

Answer 1

Might be easier to use select instead:
val df = Seq((1, "Harshit", "VNS"), (2, "Mohit", "BLR"))
.toDF("prodid", "name", "city")
df.select(df.schema.fields.map {
case StructField(name, IntegerType, _, _) => col(name)
case StructField(name, _, _, _) => format_string("\"%s\"", col(name)) as name
}:_*).show()
Output:
+------+---------+-----+
|prodid| name| city|
+------+---------+-----+
| 1|"Harshit"|"VNS"|
| 2| "Mohit"|"BLR"|
+------+---------+-----+
Note that there are other numeric types as well such as LongType and DoubleType so might need to handle these as well or alternatively just quote StringType etc.