Add support for parameterized queries

[joakimhew]

With support for parameterized queries, InfluxDB can be queried in the following manner:

var serialNumber = "F2EA2B0CDFF"
var query = "SELECT * FROM cpuTemp WHERE \"serialNumber\" = @SerialNumber";
var response = await influxDbClient.Client.QueryAsync(
     query: query, 
     param: new 
     { 
           @SerialNumber = serialNumber 
     }, 
     dbName: "yourDbName");

The signature for the new overload is:

public Task<IEnumerable<Serie>> QueryAsync(string query, object param = null, string dbName = null, string epochFormat = null, long? chunkSize = default(long?));

The supported types of parameters are primitive types as well as Strings. Trying to use un-supported types will throw a NotSupportedException.

All strings are sanitized.

[tihomir-kit]

Well man, this is some seriously nice stuff. Thanks! I'll look at it more closely tomorrow, but I like what I've been able to see by just quickly checking it out. Cheers

[joakimhew]

Just glad I could help man :) I've tested it quite a lot today and it seems to be working good. One thing worth iterating over though, is the behaviour of non-used properties. As an example. Let's say you're passing this model to the param:

var filter = new Filter 
{
     SerialNumber = "abcd1234",
     SensorId = "4321dcba"
} ;

but the query only uses an identifier for SerialNumber like so:

var query = "SELECT * FROM Measurement WHERE serialNumber = @SerialNumber";

Maybe it should see this as valid and just ignore the SensorId? I need to use this for work tomorrow so I'll keep you updated 👍

Cheers.

[tihomir-kit]

My 2c - I think we should not throw exceptions if a user passes an object that has extra properties which are not part of the query. To me this is completely fine and should not be sanitized.

[tihomir-kit]

Ok, I've looked at what you've done and I think it's great. :)

It's been on my mind to implement exactly this stuff actually for some time now, thanks.

I applied some minor renamings in the code so it matches the rest of the style of the codebase. A small breaking change is renaming of .RecordsAs<T>() to simply .As<T>(). I think it's simpler, not redundant, and still very clear. I also renamed the BuildParametarizedQuery to simply BuildQuery but I converted it to an extension method so the usage syntax is now something like queryTemplate.BuildQuery(parameters) which I believe is very clear. What do you think?

Btw one of your tests is failing - the ArgumentException for the QueryHelper. Would you please be able to take a look perhaps when you have the time (just pull from the latest dev branch)? I don't want to mess with the logic you had in mind for this.

[joakimhew]

@pootzko Awesome! I've looked through your changes and now I have a better feel for the codestyle in the project. Thanks for that! :)
All looks good to me man!

The test failing is most likely due to the correction in some regex that I did (0d12aba), sorry for that. I'll fix it later!

[joakimhew]

I'm terribly sorry that I haven't had the time to go through it man. Did you manage to find time? Otherwise I'll see if I can get some time tonigh. I've got a nice little bug fix that I think you'll enjoy haha.. I just added fill(previous) to my query which will return null values from influx. SerieExtensions doesn't like this when it tries to use Convert.ChangeType https://github.com/joakimhew/InfluxData.Net/blob/77c406be6cc0145d4acda744587febea5350325a/InfluxData.Net.InfluxDb/Helpers/SerieExtensions.cs#L65.

A solution for this is to check if the value is of type value and if so, make sure to use the Activator class to create an instance for the value:

if(propType.IsValueType && value[columnIndex] == null)
{
     value[columnIndex] = Activator.CreateInstance(propType);
}

I'll get a PR going as soon as I can with the fix and add the related tests 👍

[tihomir-kit]

Don't worry.

I just commented out that specific test that's failing, so when you have the time, I'll gladly accept another PR. :) It's easy to redeploy a simple fix. Thnx!