/
index.js
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/
index.js
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const mkdirp = require('mkdirp');
const createFile = require('create-file');
const jsonfile = require('jsonfile');
const insertAction = 'insertAction';
const createTableAction = 'createTableAction';
const selectAction = 'selectAction';
const updateAction = 'updateAction';
class jsonQl {
static generateKey() {
return Math.random().toString(36).substring(7);
}
static isRequired(param, action) {
throw new Error(` ${param} parameter missing, Unable perform ${action}`);
};
/**
* @description Creates DB folder to store table JSONs
* @param {Function} callback
*/
createDB(callback) {
mkdirp(`DB`, function (err) {
if (err) {
callback(err)
}
else {
callback({created: true})
}
})
}
/**
* @description Creates new table json
* @param {String} tableName - Table name
* @param {Array} columns - Array of columns along with type
* @param {Function} callback
*/
createTable(tableName = this.constructor.isRequired('table name', createTableAction), columns = this.constructor.isRequired('columns', createTableAction), callback) {
mkdirp(`DB/${tableName}`, function (err) {
if (tableName && columns) {
if (err) callback(err);
else {
let content = {items: {}, columnsInfo: {}};
columns.forEach(column => {
content.columnsInfo[column.split(' ')[0]] = column.split(' ')[1]
});
createFile(`DB/${tableName}/index.json`, JSON.stringify(content), function () {
callback({created: true})
})
}
} else {
callback({error: 'Parameters invalid'})
}
})
}
/**
* @description Insert data into table
* @param {String} tableName - Table name
* @param {Array} columns - Array of columns names
* @param {Array} values - Array of values
* @param {Function} callback
*/
insertInto(tableName = this.constructor.isRequired('table name', insertAction), columns = this.constructor.isRequired('columns', insertAction), values = this.constructor.isRequired('values', insertAction), callback) {
let error = null;
columns.length === values.length ?
jsonfile.readFile(`DB/${tableName}/index.json`, (err, obj) => {
if (err) {
callback({error: err})
} else {
if (columns.map(column => {
return obj.columnsInfo.hasOwnProperty(column)
}).includes(false)) {
callback({error: 'Columns name error'})
} else {
if (JSON.stringify(Object.keys(obj.columnsInfo)) === JSON.stringify(columns)) {
if (values.map((value, i) => {
return typeof(value) === Object.values(obj.columnsInfo)[i]
}).includes(false)) {
callback({error: 'Invalid value Type'})
} else {
jsonfile.readFile(`DB/${tableName}/index.json`, (err, obj) => {
let newTableData = {...obj};
const uniqueKey = this.constructor.generateKey();
newTableData.items[uniqueKey] = {};
columns.forEach((column, index) => {
newTableData.items[uniqueKey][column] = values[index]
});
jsonfile.writeFile(`DB/${tableName}/index.json`, newTableData, {}, () => {
callback({error: null, inserted: true})
})
})
}
} else {
callback({error: 'Error:Column order mismatched'})
}
}
}
}) :
callback({error: 'columns and values are mis matching'})
}
/**
* @description Read table data
* @param {String} tableName - Table name
* @param {Array|string} columns - Array of columns names || * to fetch all columns
* @param {Function} callback
*/
selectItem(tableName = this.constructor.isRequired('table name', selectAction), columns = this.constructor.isRequired('columns', selectAction), callback) {
jsonfile.readFile(`DB/${tableName}/index.json`, (err, obj) => {
let new_obj = {...obj}
if (columns === '*') {
callback({data: obj.items})
} else {
let result = {}
result.data =
Object.keys(new_obj.items).map(key => {
let selectedRow = {}
selectedRow[key] = {}
columns.forEach(column => {
selectedRow[key][column] = new_obj.items[key][column]
})
return selectedRow
})
callback(result)
}
})
}
}
module.exports = jsonQl;