Convert string to int in an Entity Framework linq query and handling the parsing exception

Question

I've got this problem, I have a table for purchases ``` Purchases(Date DateTime, Number string) ``` I want is to create a new record, so I need the Max(Number), the problem here is that Number is a string, I've tried ``` Purchases.Select(X=>int.Parse(X.Number)).Max() ``` but it could throw an exception, I've create a custom `ToInt()` extension so when I use ``` Purchases.Select(X=>X.Number.ToInt()).Max() ``` it throws an exception saying that my ToInt() can't be used with linq query same as the famous ToString() so my question is : is there a way to cast a string to int in linq query & handling exceptions at the same time or to integrate custom functions to a linq query !! and this's my extension ``` public static int ToInt(this string s) { try { return int.Parse(s); } catch { } return 0; } ```

Accepted Answer

First way:

```
var numbers = Purchases.Select(x => x.Number).ToList();

int temp;
int max = numbers.Select(n => int.TryParse(n, out temp) ? temp : 0).Max();

Console.WriteLine("Max: {0}", max);
```

Second way:

```
int temp2;
int max2 = Purchases.Select(x => x.Number).ToList().Select(n => int.TryParse(n, out temp2) ? temp2 : 0).Max();

Console.WriteLine("Max 2: {0}", max2);
```

The key is the `.ToList()` in those two ways. It gets all the `string` data from the database, so when you call `int.TryParse` on the results, the database query has already been run, so it is using pure CLR code, and not trying to convert `int.TryParse` into a SQL query. I made an EF context in one of my Sandbox projects and verified this works.

Convert string to int in an Entity Framework linq query and handling the parsing exception

Solution

Problem