Simplify the csv examples API by forcing to returna and write object arrays

Author: Irene Alvarado

csv.ts

@@ -1,11 +1,24 @@
 import { parse, ParseOptions } from 'https://deno.land/[email protected]/encoding/csv.ts'
+import { DataItem, stringify } from 'https://deno.land/[email protected]/encoding/csv.ts';
+
+export async function readCSV(path: string, options?: ParseOptions): Promise<Record<string, unknown>[]> {
+    if (!options || !('skipFirstRow' in options)) {
+        // to force library to be consistent and return an array of objects
+        options = { 
+            ...options,
+            skipFirstRow: true
+        }
+    }
 
-export async function readCSV(path: string, options?: ParseOptions): Promise<unknown> {
     const raw = await Deno.readTextFile(path)
     const content = await parse(raw, options)
-    return content
+    return content as Record<string, unknown>[]
 }
 
-export async function writeCSV(path: string, data: string) {
-    await Deno.writeTextFile(path, data);
+export async function writeCSV(path: string, data: Record<string, unknown>[]) {
+    const headers = Object.keys(data[0])
+    // we have to stringify the data with a row header
+    const dataString = await stringify(data as DataItem[], headers)
+
+    await Deno.writeTextFile(path, dataString);
 }

examples/csv/csv-example.ts

@@ -1,38 +1,30 @@
-import { Column, DataItem, stringify } from 'https://deno.land/[email protected]/encoding/csv.ts';
-import { readCSV, writeCSV } from 'https://deno.land/x/[email protected]/mod.ts'
+import { readCSV, writeCSV } from '../../csv.ts'
 
 // Path to a csv file
 const csvPath = './examples/csv/prices.csv';
 
 /* 
-Parse a csv file and return a string[][]
+Parse a csv file and return an object[]
 
 [
-  [ "Name", "Amount", "Price" ],
-  [ "One", "500", "$0.5" ],
-  [ "Two", "13", "$10" ],
-  [ "Three", "-3", "$3000" ]
+  { Name: "One", Amount: "500", Price: "$0.5" },
+  { Name: "Two", Amount: "13", Price: "$10" },
+  { Name: "Three", Amount: "-3", Price: "$3000" }
 ]
 */
 const originalCSV = await readCSV(csvPath)
 console.log(originalCSV)
 
 /*
-Parse a CSV file and skip the first row. Return an object[]
-
-[
-  { Name: "One", Amount: "500", Price: "$0.5" },
-  { Name: "Two", Amount: "13", Price: "$10" },
-  { Name: "Three", Amount: "-3", Price: "$3000" }
-]
+Can use other options for reading CSV
+More detail on options can be found here: https://deno.land/[email protected]/encoding#csv
 */
-const skipFirstRowCSV = await readCSV(csvPath, { 
-    skipFirstRow: true
-    // separator: ',' // can use an optional separator. default is comma
-    // trimLeadingSpace: false, // whether to trim the leading space. default is false
-    // lazyQuotes: false // Allow unquoted quote in a quoted field or non double quoted quotes in quoted field. default is false
+const csvOptions = await readCSV(csvPath, { 
+    separator: ',', // can use an optional separator. default is comma
+    trimLeadingSpace: false, // whether to trim the leading space. default is false
+    lazyQuotes: false // Allow unquoted quote in a quoted field or non double quoted quotes in quoted field. default is false
 })
-console.log(skipFirstRowCSV);
+console.log(csvOptions);
 
 /*
 Parse a CSV file, skip the first row, and rename the column headers. Return an object[]
@@ -44,7 +36,6 @@ Parse a CSV file, skip the first row, and rename the column headers. Return an o
 ]
 */
 const renameColumnsCSV = await readCSV(csvPath, {
-    skipFirstRow: true,
     columns: ['id', 'quantity', 'cost'],
 });
 console.log(renameColumnsCSV);
@@ -59,7 +50,6 @@ Parse a CSV file, skip the first row, and apply a custom function to the second
 ]
 */
 const parseColumnCSV = await readCSV(csvPath, {
-    skipFirstRow: true,
     columns: [
         { 
             name: 'id'
@@ -78,27 +68,23 @@ const parseColumnCSV = await readCSV(csvPath, {
 console.log(parseColumnCSV)
 
 /*
-Write data to a file with a header row
+Write data to a CSV file
 
-name,age
-Rick,70
-Smith,14
+age,name
+70,Rick
+14,Smith
 */
 const data = [
-    {
+    { 
         age: 70,
-        name: "Rick"
+        name: 'Rick'
     },
     {
         age: 14,
-        name: "Smith"
-    },
-];
-const columns: Column[] = ["name", "age"];
-
-// we have to stringify the data with a row header
-const dataString = await stringify(data, columns)
-writeCSV('./examples/csv/names.csv', dataString)
+        name: 'Smith'
+    }
+]
+writeCSV('./examples/csv/names.csv', data)
 
 /*
 Write one of the previously parsed csv examples
@@ -108,7 +94,5 @@ One,50,$0.5
 Two,1.3,$10
 Three,-0.3,$3000
 */
-const data2 = parseColumnCSV as DataItem[]; // have to recast the output
-const columns2: Column[] = ["id", "quantity", "cost"];
-const dataString2 = await stringify(data2, columns2)
-writeCSV('./examples/csv/prices-write.csv', dataString2)
+console.log(parseColumnCSV)
+writeCSV('./examples/csv/prices-write.csv', parseColumnCSV)

examples/csv/names.csv

@@ -1,3 +1,3 @@
-name,age
-Rick,70
-Smith,14
+age,name
+70,Rick
+14,Smith