Rewrite in Bash + jq (#5)

* Port Scala project to Bash + jq

* Update CI to run Bash/jq tests

* Restore full example in README.md

* Add dependency and usage checks

* Add input validation and better error messaging

* Reorganize to packaged structure (bin/ directory)

* Rename script to bigquery-schema-select to match project name

* Add backtick quoting for BigQuery reserved keywords and update tests

* Add unit test for reserved keyword quoting

* Update README.md with motivation and quoted SQL example

* Highlight avoidance of SELECT * and manual rewriting in Motivation

* Refine README motivation: Public API analogy and more general medallion architecture description

* Add bq tool check and update README prerequisites

Author: fpopic

.github/workflows/scala.yml .github/workflows/ci.yml.github/workflows/scala.yml renamed to .github/workflows/ci.yml

@@ -1,4 +1,4 @@
-name: Scala CI
+name: CI
 
 on:
   push:
@@ -7,14 +7,9 @@ on:
     branches: [ master ]
 
 jobs:
-  build:
+  test:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
-    - uses: actions/setup-java@v3
-      with:
-        distribution: 'temurin'
-        java-version: '17'
-        cache: 'sbt'
     - name: Run tests
-      run: sbt test
+      run: ./run-tests.sh

.scalafmt.conf

@@ -1,33 +1,39 @@
 # bigquery-schema-select
 
-![Scala CI](https://github.com/fpopic/bigquery-schema-select/workflows/Scala%20CI/badge.svg) 
-[<img src="https://img.shields.io/maven-central/v/com.github.fpopic/bigquery-schema-select_2.13.svg?color=brightgreen&label=maven%20central%202.13"/>](https://search.maven.org/#search%7Cga%7C1%7Cbigquery-schema-select_2.13)
-
 Generates SQL query that selects all fields (recursively for nested fields) from the provided BigQuery schema file.
 
-### Installation
+### Motivation
 
-Download latest version `bigquery-schema-select_2.13-X.Y.jar` from [maven releases UI](https://repo1.maven.org/maven2/com/github/fpopic/bigquery-schema-select_2.13/) or using CLI:
+This tool is designed to help automate the creation of **explicit BigQuery views** that act as a strict schema "contract" between different layers of a medallion architecture. Think of these views as the **Public API** for your data: they provide a stable, documented interface that shields downstream consumers from the complexities and changes of the underlying raw data.
 
-```shell script
-# replace X.Y with the latest version
-wget -O ~/bigquery-schema-select_2.13-X.Y.jar https://repo1.maven.org/maven2/com/github/fpopic/bigquery-schema-select_2.13/X.Y/bigquery-schema-select_2.13-X.Y.jar
-```
+By generating an explicit `SELECT` statement that recursively expands `RECORD` and `REPEATED RECORD` types, it ensures that your views:
+- **Prevent Schema Drift**: New fields added to the underlying source table will not be exposed in the view until you explicitly update the schema and regenerate it (avoiding the pitfalls of `SELECT *`).
+- **Maintain Structure**: Uses `STRUCT(...)` and `ARRAY(SELECT AS STRUCT ...)` to fully specify the output record structure and maintain array order using `WITH OFFSET`.
+- **Enforce Naming Standards**: Optionally aliases camelCase fields to snake_case (using the `--use_snake_case` flag) to maintain a consistent naming convention across your data products.
+- **Automate Redundancy**: Avoids the error-prone and tedious process of manually rewriting complex nested SQL for dozens or hundreds of fields.
+
+### Prerequisites
+
+- `jq` installed on your system.
+- `bash` shell.
 
 ### Usage
 
 Using existing table: 
 
 ```shell script
-bq show --schema --format=prettyjson my_project:my_dataset.my_table | java -jar ~/bigquery-schema-select_2.13-X.Y.jar
+bq show --schema --format=prettyjson my_project:my_dataset.my_table | ./bin/bigquery-schema-select
 ```
 
 Using JSON schema file:
 
 ```shell script
-cat my_schema.json | java -jar ~/bigquery-schema-select_2.13-X.Y.jar
+cat my_schema.json | ./bin/bigquery-schema-select
 ```
 
+#### Example
+
+Input `my_schema.json`:
 ```json
 [
   {
@@ -116,49 +122,56 @@ cat my_schema.json | java -jar ~/bigquery-schema-select_2.13-X.Y.jar
 ]
 ```
 
-Would generate:
+Generates:
 ```sql
 SELECT
-  A,
-  B,
+  `A`,
+  `B`,
   STRUCT(
     STRUCT(
-      C.D.E,
+      `C`.`D`.`E`,
       ARRAY(
         SELECT AS STRUCT
-          F.G
+          `F`.`G`
         FROM
-          UNNEST(C.D.F) AS F
+          UNNEST(`C`.`D`.`F`) AS `F`
         WITH
           OFFSET
         ORDER BY
           OFFSET
-      ) AS F
-    ) AS D,
-    C.H
-  ) AS C,
+      ) AS `F`
+    ) AS `D`,
+    `C`.`H`
+  ) AS `C`,
   STRUCT(
-    I.J,
-    I.K
-  ) AS I,
+    `I`.`J`,
+    `I`.`K`
+  ) AS `I`,
   ARRAY(
     SELECT AS STRUCT
-      L.M,
-      L.N,
+      `L`.`M`,
+      `L`.`N`,
       STRUCT(
-        L.O.P
-      ) AS O
+        `L`.`O`.`P`
+      ) AS `O`
     FROM
-      UNNEST(L) AS L
-    WITH 
+      UNNEST(`L`) AS `L`
+    WITH
       OFFSET
     ORDER BY
       OFFSET
-  ) AS L,
-  Q
+  ) AS `L`,
+  `Q`
 ```
 
 In case you would like to use snake_case for field names use flag `--use_snake_case`:
 ```shell script
-cat my_schema.json | java -jar ~/bigquery-schema-select_2.13-X.Y.jar --use_snake_case
+cat my_schema.json | ./bin/bigquery-schema-select --use_snake_case
+```
+
+### Development
+
+Run tests:
+```shell script
+./run-tests.sh
 ```

README.md

@@ -0,0 +1,78 @@
+#!/bin/bash
+
+# Ported from Scala to Bash + jq
+
+# Check for dependencies
+if ! command -v jq >/dev/null 2>&1; then
+  echo "Error: jq is not installed. Please install it (e.g., 'brew install jq' or 'sudo apt install jq')." >&2
+  exit 1
+fi
+
+if ! command -v bq >/dev/null 2>&1; then
+  echo "Warning: bq (Google Cloud SDK) is not installed. You can still use this tool with JSON files, but you won't be able to fetch schemas directly from BigQuery." >&2
+fi
+
+# Check for input (stdin)
+if [[ -t 0 ]]; then
+  echo "Usage: cat schema.json | $0 [--use_snake_case]" >&2
+  echo "Or: bq show --schema --format=prettyjson project:dataset.table | $0" >&2
+  exit 1
+fi
+
+# Read input once
+INPUT=$(cat)
+
+# Validate JSON input
+if ! echo "$INPUT" | jq -e . >/dev/null 2>&1; then
+  echo "Error: Input is not valid JSON." >&2
+  if echo "$INPUT" | grep -iq "BigQuery error"; then
+    echo "The input contains a BigQuery error. Please ensure your table reference follows the 'project:dataset.table' format (with a colon after the project ID)." >&2
+  fi
+  exit 1
+fi
+
+USE_SNAKE_CASE=false
+if [[ "$1" == "--use_snake_case" ]]; then
+  USE_SNAKE_CASE=true
+fi
+
+echo "$INPUT" | jq -r --argjson useSnakeCase "$USE_SNAKE_CASE" '
+  def quoteName(name): "`" + name + "`";
+
+  def calculateFieldName(name; useSnakeCase):
+    if (useSnakeCase | not) then name
+    else
+      (name | split("") | .[0] |= ascii_downcase | .[0] as $first | .[1:] | 
+       reduce .[] as $char (""; . + (if ($char | test("[A-Z]")) then "_" + ($char | ascii_downcase) else $char end))
+       | $first + .)
+    end;
+
+  def toSelectClauseRecursive(current; depth; prefix; useSnakeCase):
+    (if (prefix == null) then quoteName(current.name) else prefix + "." + quoteName(current.name) end) as $fullyQualifiedName |
+    ("  " * depth) as $indent |
+    calculateFieldName(current.name; useSnakeCase) as $calculatedFieldName |
+    quoteName($calculatedFieldName) as $quotedCalculatedFieldName |
+    (if (useSnakeCase and $calculatedFieldName != current.name) then " AS " + $quotedCalculatedFieldName else "" end) as $alias |
+    
+    if (current.type != "RECORD") then
+      $indent + $fullyQualifiedName + $alias
+    elif (current.type == "RECORD" and current.mode == "REPEATED") then
+      quoteName(current.name) as $currentNameQuoted |
+      ($indent + "ARRAY(\n" +
+       $indent + "  SELECT AS STRUCT\n" +
+       (current.fields | map(toSelectClauseRecursive(.; depth + 2; $currentNameQuoted; useSnakeCase)) | join(",\n")) + "\n" +
+       $indent + "  FROM\n" +
+       $indent + "    UNNEST(" + $fullyQualifiedName + ") AS " + $currentNameQuoted + "\n" +
+       $indent + "  WITH\n" +
+       $indent + "    OFFSET\n" +
+       $indent + "  ORDER BY\n" +
+       $indent + "    OFFSET\n" +
+       $indent + ") AS " + $quotedCalculatedFieldName)
+    else
+      ($indent + "STRUCT(\n" +
+       (current.fields | map(toSelectClauseRecursive(.; depth + 1; $fullyQualifiedName; useSnakeCase)) | join(",\n")) + "\n" +
+       $indent + ") AS " + $quotedCalculatedFieldName)
+    end;
+
+  "SELECT\n" + (map(toSelectClauseRecursive(.; 1; null; $useSnakeCase)) | join(",\n"))
+'

bin/bigquery-schema-select

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+# Test script for bq-schema-select.sh
+
+set -e
+
+echo "Running tests for bq-schema-select.sh..."
+
+echo "Test 1: my_schema.json"
+./bin/bigquery-schema-select < test-resources/my_schema.json | diff - test-resources/my_select.sql
+echo "Test 1 passed!"
+
+echo "Test 2: my_camel_schema.json --use_snake_case"
+./bin/bigquery-schema-select --use_snake_case < test-resources/my_camel_schema.json | diff - test-resources/my_camel_select.sql
+echo "Test 2 passed!"
+
+echo "Test 3: my_camel_short_schema.json --use_snake_case"
+./bin/bigquery-schema-select --use_snake_case < test-resources/my_camel_short_schema.json | diff - test-resources/my_camel_short_select.sql
+echo "Test 3 passed!"
+
+echo "Test 4: my_reserved_schema.json"
+./bin/bigquery-schema-select < test-resources/my_reserved_schema.json | diff - test-resources/my_reserved_select.sql
+echo "Test 4 passed!"
+
+echo "All tests passed!"