add first version

.gitignore

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+*.db
+*.json
+.idea/

main.py

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+# This is a sample Python script.
+import ijson
+import sqlite3
+
+# Press ⌃R to execute it or replace it with your code.
+# Press Double ⇧ to search everywhere for classes, files, tool windows, actions, and settings.
+
+flat_keys = ["cost_center", "location", "customer"]
+extract_keys = {
+    "price_modifiers": {
+        "flat_keys": [],
+        "extract_keys": {}
+    },
+    "sale_items": {
+        "flat_keys": [],
+        "extract_keys": {
+            "categories": {
+                "key": "categories",
+            },
+            "modifiers": {
+                "key": "modifiers",
+                "flat_keys": [],
+                "extract_keys": {
+                    "categories": {
+                        "key": "categories",
+                    }
+                }
+            }
+        }
+    }
+}
+
+parent = "transactions"
+con = sqlite3.connect(f"{parent}.db")
+cur = con.cursor()
+
+
+def extract_child(merge_headers, item, k, ext, prev_step):
+    child_headers = merge_headers.get(k, [])
+
+    for child in item[k]:
+        for (subKey, subValue) in child.items():
+            is_ext = subKey in ext.get("extract_keys", {}).keys()
+            if is_ext:
+                extract_child(merge_headers, child, subKey, ext["extract_keys"][subKey], f"{prev_step}{k}_")
+            else:
+                child_header = f"{k}_{subKey}"
+                if child_header not in child_headers:
+                    child_headers.append(child_header)
+
+    merge_headers[f"{prev_step}{k}"] = child_headers
+
+
+global_counter = 1
+
+
+def extract_child_value(merge_headers, item, k, ext, prev_step):
+    child_value = {}
+    for child in item[k]:
+        for (subKey, subValue) in child.items():
+            is_ext = subKey in ext.get("extract_keys", {}).keys()
+            if is_ext:
+                extract_child_value(merge_headers, child, subKey, ext["extract_keys"][subKey], f"{prev_step}{k}_")
+            else:
+                child_header = f"{k}_{subKey}"
+                child_value[child_header] = subValue
+
+    k_ = f"{prev_step}{k}"
+    write_to_database(k_, child_value)
+
+
+def make_table(tbl_name, cols):
+    syspk = "syspk integer primary key autoincrement"
+    other_cols = ', '.join([f"{f} TEXT" for f in cols])
+    create_tbl_sql = f"create table if not exists {tbl_name} ({syspk}, {other_cols})"
+    print(f"{tbl_name} = ", cols)
+    print(f"{tbl_name} = ", create_tbl_sql)
+    cur.execute(create_tbl_sql)
+
+
+def write_to_database(tbl, cols):
+    keys = cols.keys()
+
+    col_names = ', '.join(
+        [x for x in keys]
+    )
+    value_placeholders = ', '.join(
+        ["?" for x in keys]
+    )
+
+    values = tuple([str(cols[k]) for k in keys])
+
+    sql = f"insert into {tbl} ({col_names}) values({value_placeholders})"
+
+    print(f"execute {sql} with values {values}")
+
+    cur.execute(sql, values)
+
+
+def parse_json():
+    extract_keys_names = extract_keys.keys()
+    headers = []
+    merge_headers = {}
+
+    # first pass, collect all headers
+    for item in ijson.items(open("transactions.json"), "item"):
+        keys = item.keys()
+        for k in keys:
+            if k in flat_keys:
+                for (fk, fv) in item[k].items():
+                    composite_key = f"{k}_{fk}"
+                    if composite_key not in headers:
+                        headers.append(composite_key)
+            elif k in extract_keys_names:
+                ext = extract_keys[k]
+                extract_child(merge_headers, item, k, ext, f"{parent}_")
+
+            else:
+                if k not in headers:
+                    headers.append(k)
+
+    make_table(parent, headers)
+
+    for (mhKey, mhVal) in merge_headers.items():
+        make_table(mhKey, mhVal)
+
+    # second pass, make flat json from original-json, create csv ( we will use sqlite, as it is faster to write)
+
+    for item in ijson.items(open("transactions.json"), "item"):
+        keys = item.keys()
+        flat_json = {}
+        for k in keys:
+            if k in flat_keys:
+                for (fk, fv) in item[k].items():
+                    composite_key = f"{k}_{fk}"
+                    flat_json[composite_key] = fv
+            elif k in extract_keys_names:
+                ext = extract_keys[k]
+                extract_child_value(merge_headers, item, k, ext, f"{parent}_")
+            else:
+                flat_json[k] = item[k]
+
+        write_to_database(parent, flat_json)
+        con.commit()
+
+
+# Press the green button in the gutter to run the script.
+if __name__ == '__main__':
+    parse_json()
+
+# See PyCharm help at https://www.jetbrains.com/help/pycharm/

requirements.txt

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+ijson