How can I insert data inside parentheses? Dart - dart

There are inputs:
String SQL = "INSERT INTO table () VALUES ()";
List data1 = ['user_id', 'user_name'];
List data2 = ['1', 'test']
How can I get "INSERT INTO table (user_id, user_name) VALUES (1, test)"? Thank you.


You can do this with String interpolation ${}
void main() {
List data1 = ['user_id', 'user_name'];
List data2 = ['1', 'test'];
String SQL = "INSERT INTO table (${data1[0]}, ${data1[1]}) VALUES (${data2[0]}, ${data2[1]})";
print(SQL);
}
DartPad sample: https://dartpad.dev/?id=39a56cbf2b5cab254902ac7aa3a4324f

Related

Dynamic wheres using TypeORM

I need to generate a query that looks something like:
SELECT v.* FROM versions v
WHERE
(v.id1 = 1 AND v.id2 = 1) OR
(v.id1 = 3 AND v.id2 = 2) OR
(v.id1 = 5 AND v.id2 = 6) OR ...
The parameter to my function contains a list of these paired ids. Unfortunately, id1 and id2 are not the primary keys of this table so I can't use .whereIdsIn().
I am aware of the Brackets object but can't for the life of me figure out how to create a dynamic number of them.

Since you put a generic query, I'll try to answer this generally. You can do something like this:
async foo(tupleList: [number, number][]) {
const builder = createQueryBuilder(Version, 'v');
for (const tuple of tupleList) {
builder.orWhere(new Brackets(qb => {
qb.where("v.id1 = :id1", { id1: tuple[0] })
.andWhere("v.id2 = :id2", { id2: tuple[1] })
}));
}
const result = await builder.getMany();
}

Combining multiple items by condition within a single list

As in Dart you can combine several list items into one according to the following condition:
Given List<String> arr = ['2','3','b','*','4','5','6','-','3','4'];
Get arr = ['23','b','*','456','-','34'];
The list is unknown in advance. It can be of any length and with any sequence of characters. And need to combine only the lines that have numbers in them.
I would be grateful for any suggestions.

You are not describing what should happen if there are multiple special characters or letters. So I have made my example so it will only combine numbers:
void main() {
final arr = ['2', '3', 'b', '*', '4', '5', '6', '-', '3', '4'];
print(combine(arr)); // [23, b, *, 456, -, 34]
}
List<String> combine(List<String> input) {
final output = <String>[];
final buffer = StringBuffer();
for (final string in input) {
if (int.tryParse(string) == null) {
if (buffer.isNotEmpty) {
output.add(buffer.toString());
buffer.clear();
}
output.add(string);
} else {
buffer.write(string);
}
}
if (buffer.isNotEmpty) {
output.add(buffer.toString());
}
return output;
}

You can use ''.join() here:
arr = [''.join(arr[0:2]), arr[2], arr[3], ''.join(arr[4:7]), arr[7], ''.join(arr[8:10])]
If you only want to have a condition where you only join numerical values then you can add a for loop beforehand.

functional construct for flattening array for multiple row insert sql query

Is there a way to generate multiple row sql query (values only) using some functional constructs of array?
I've an array of Roles that I want to insert into sqlite database.
struct Role {
var id: Int32
var name: String?
}
func updateByUserId(_ id: Int32, _ roles: [Role]) {
let sql = "INSERT INTO user_role(user_id, role_id) VALUES( \(id), \(roles.map..) )"
}
Expectation:
for instances if id is 1 and roles has an array [10, 11, 14, 15]
Generated SQL should be
INSERT INTO user_role(user_id, role_id) VALUES(1, 10), (1, 11), (1, 14), (1, 15)
SQL Syntax for Multiple row insert is
INSERT INTO MyTable ( Column1, Column2 ) VALUES(Value1, Value2),
(Value1, Value2)

You can map each role to the string (id, role), then join the array of strings with the separator ,:
let values = roles.map { "(\(id), \($0))" }.joined(separator: ", ")
let sql = "INSERT INTO user_role(user_id, role_id) VALUES\(values)"

Although for this particular scenario the SQL string computation is not problematic, it's good practice to use parametrized statements for every DB query.
Working exclusively with parametrized statements avoids vulnerabilities like SQL injection, or malformed queries that fail to execute (when dealing with strings instead of ints).
So, I'd recommend going via the above route by writing something like this:
func updateByUserId(_ id: Int32, _ roles: [Role]) -> (statement: String, params: [Int32]) {
let statement = "INSERT INTO user_role(user_id, role_id) VALUES " + Array(repeating: "(?, ?)", count: roles.count).joined(separator: ", ")
let params = roles.flatMap { [id, $0.id] }
return (statement, params)
}
For your example in the question, the output would be something like this:
(statement: "INSERT INTO user_role(user_id, role_id) VALUES (?, ?), (?, ?), (?, ?), (?, ?)", params: [1, 10, 1, 11, 1, 14, 1, 15])
You can then use the SQLite functions to create the parametrized statement and bind the given values to it.
P.S. There is also the matter of validating that the array of roles is not empty, in which case you'd get an invalid SQL as output. To handle this, you can make the function return an optional, and nil will signal an empty array. Doing this will enable a small performance improvement, as you'll be able to use String(repeating:count:), which is a little bit faster than creating an array and joing it later on:
func updateByUserId(_ id: Int32, _ roles: [Role]) -> (statement: String, params: [Int32])? {
guard !roles.isEmpty else { return nil }
return (statement: "INSERT INTO user_role(user_id, role_id) VALUES (?, ?)" + String(repeating: ", (?, ?)", count: roles.count - 1),
params: roles.flatMap { [id, $0.id] })
}

Getting stackoverflow on recursion

I want to generate INSERT statement from JSON. The problem that I have problem with recursion (in section where I am getting nested elements). it's seems that I am getting SO.
import 'dart:convert';
main() {
Map jsonMap = jsonDecode(
'{"id":"1","name":"sample","Lots":[{"id":"1","title":"books","objs":[{"book":"name"}]}]}');
KVToTableInsert(String tablename, Map jsonMap) {
List<String> insertNoticeKeys = [];
List<String> insertNoticeValues = [];
jsonMap.forEach((key, value) {
if (value is List) // nested
{
KVToTableInsert(key, jsonMap); // if comment this line all work
} else {
insertNoticeKeys.add(key);
insertNoticeValues.add(value);
}
});
String sql = "INSERT INTO $tablename (" +
insertNoticeKeys.map((e) => '"$e"').join(', ') +
") VALUES (" +
insertNoticeValues.map((e) => "'$e'").join(', ') +
")";
print(sql);
}
KVToTableInsert("RootTable", jsonMap);
}
I expected to get 3 INSERT statment:
INSERT INTO RootTable ("id", "name") VALUES ('1', 'sample')
INSERT INTO Lots ("id", "title") VALUES ('1', 'books')
INSERT INTO Objs ("book") VALUES ('name')
But I am getting crush on this app.

There was a slight problem in your code, basically in this part:
if (value is List){
KVToTableInsert(key, jsonMap); // if comment this line all work
}
If you closely, take a look at your KVToTableInsert, you're passing arguments Map and not list. Which fails your recursion.
What you need to do is to pass the item of the array, into your KVToTableInsert, and this will work as expected
FINAL SOLUTION
// taking your jsonMap directly, and not decoding it
void main() {
Map jsonMap = {
"id":"1",
"name":"sample",
"Lots":[
{
"id": "1",
"title":"books",
"objs":[
{
"book":"name"
}
]
}
]
};
void KVToTableInsert(tablename, jsonMap){
List<String> insertNoticeKeys = [];
List<String> insertNoticeValues = [];
jsonMap.forEach((key,value){
if (value is List)
{
// Here is the magic, you need to iterate over your list, and pass MAP, not LIST
value.forEach((item){ KVToTableInsert(key, item);});
} else {
insertNoticeKeys.add(key);
insertNoticeValues.add(value);
}
});
String sql = "INSERT INTO $tablename (" +
insertNoticeKeys.map((e) => '"$e"').join(', ') +
") VALUES (" +
insertNoticeValues.map((e) => "'$e'").join(', ') +
")";
print(sql);
}
KVToTableInsert("Rootable", jsonMap);
}
OUTPUT
INSERT INTO objs ("book") VALUES ('name')
INSERT INTO Lots ("id", "title") VALUES ('1', 'books')
INSERT INTO Rootable ("id", "name") VALUES ('1', 'sample')
Also, look at the Dart Programming Language Naming Conventions, it is a good practise to use lowerCamelCase for your function/method name.

how to insert new row by using executeUpdate - FMdatabase

I'm using fmdb library.
https://github.com/ccgus/fmdb
I would like to insert new records but I don't know how can I do:
if let db = database, let q = db.executeUpdate("insert into \(table) (catid,subcat_id,id,subcat_title,title,description,lat,lon,takhfif,images,wifi,apple_health,wc,full_time,pos,work_hours,phone,mobile,fax,website,email,address,facebook,instagram,linkedin,telegram,googleplus,twitter,publish,feature,manager,city,rating_sum,rate_count,lastip,parking,isMallID,mallID,discount_images,price_images,newProduct_images,services_images,order_online,out_upon,cat_title,cat_icon,last_modify,item_logo,cat_logo,rate_sum1,rate_sum2,rate_sum3,rate_count1,rate_count2,rate_count3,rate_title1,rate_title2,rate_title3,rate_enable) values (\(catid),\(subcat_id),\(id),'\(subcat_title)','\(title)','\(description)','\(lat)','\(lon)','\(takhfif)','\(images)',\(wifi),\(apple_health),\(wc),\(full_time),\(pos),'\(work_hours)','\(phone)','\(mobile)','\(fax)','\(website)','\(email)','\(address)','\(facebook)','\(instagram)','\(linkedin)','\(telegram)','\(googleplus)','\(twitter)',\(publish),\(feature),'\(manager)','\(city)',\(rating_sum),\(rate_count),'\(lastip)',\(parking),\(isMallID),\(mallID),'\(discount_images)','\(price_images)','\(newProduct_images)','\(services_images)',\(order_online),\(out_upon),'\(cat_title)','\(cat_icon)',\(last_modify),'\(item_logo)','\(cat_logo)',\(rate_sum1),\(rate_sum2),\(rate_sum3),\(rate_count1),\(rate_count2),\(rate_count3),'\(rate_title1)','\(rate_title2)','\(rate_title3)',\(rate_enable))") {
}
but I got this message before building:
cannot invoke executeUpdate with an argument list of type string

You used the api wrong. The first parameter is the sql, each value has to be represented with an "?". The second one (values) is an array of the values. Try this:
if let db = database, let q = db.executeUpdate(
"insert into \(table) (catid,subcat_id,id,subcat_title,title,description,lat,lon,takhfif,images,wifi,apple_health,wc,full_time,pos,work_hours,phone,mobile,fax,website,email,address,facebook,instagram,linkedin,telegram,googleplus,twitter,publish,feature,manager,city,rating_sum,rate_count,lastip,parking,isMallID,mallID,discount_images,price_images,newProduct_images,services_images,order_online,out_upon,cat_title,cat_icon,last_modify,item_logo,cat_logo,rate_sum1,rate_sum2,rate_sum3,rate_count1,rate_count2,rate_count3,rate_title1,rate_title2,rate_title3,rate_enable) values (?, ?, ? ...., ?, ?, ? )"
values: [catid, subcat_id, id, subcat_title, title, description, lat, lon, takhfif, images, wifi, apple_health, wc, full_time, pos, work_hours, phone, mobile, fax, website, email, address, facebook, instagram, linkedin, telegram, googleplus, twitter, publish, feature, manager, city, rating_sum, rate_count, lastip, parking, isMallID, mallID, discount_images, price_images, newProduct_images, services_images, order_online, out_upon, cat_title, cat_icon, last_modify, item_logo, cat_logo, rate_sum1, rate_sum2, rate_sum3, rate_count1, rate_count2, rate_count3, rate_title1, rate_title2, rate_title3, rate_enable]) {
}
Note: I didn't count the values, so you have to ensure that the count of "?" inside of the string is exactly the count of your values!
Maybe you should think about a function to improve the readability of your code. Something like that:
extension FMDatabase {
func insert(into table: String, row values: [(column: String, content: Any)]) {
guard (values.count > 0) else { fatalError(values.count > 0, "Inserting nothing into a table makes no sense!") }
var sql = "INSERT INTO \(table) ("
var contents: [Any] = []
for (index, value) in values.enumerated() {
sql += index == 0 ? value.column : ", \(value.column)"
contents.append(value.content)
}
sql += ") VALUES ("
for index in 0..<values.count {
sql += index == 0 ? "?" : ", ?"
}
sql += ")"
executeUpdate(sql, values: contents)
}
}
Then you can insert values like that:
if let db = database {
db.insert(
into: table,
row: [
(column: "catid", content: catid),
(column: "subcat_id", content: subcat_id),
...
(column: "rate_enable", content: rate_enable)
]
)
}
Isn't it better readable?

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