I am reading a table from a sqlite3 database. I managed to read an int field ( iEventYear in my code sample )
But I don't know howto read a string field from sqlite database.
I would like to use no additional library or framework, but the pure included sqlite3.h if possible.
Here's my code to demonstrate my problem:
let sql = "SELECT year,title FROM historyevents";
var statement:COpaquePointer = nil
//var tail: CString = ""
if sqlite3_prepare_v2(db, sql, -1, &statement, nil) != SQLITE_OK {
println("Failed to prepare statement")
exit(1)
}else{
while sqlite3_step(statement) == SQLITE_ROW {
var iEventYear:Int16 = Int16(sqlite3_column_int(statement, 0));
//Howto retrieve a string ?
var sEventTitle:String = String(sqlite3_column_xxxxxx(statement, 1));
println(count);
}
println("query ok.");
}
You should be able to retrieve a String in this way.
let sEventTitle = String.fromCString(UnsafePointer<CChar>(sqlite3_column_text(statement, 1)))
However my advice is to use a SQLite wrapper, one of the most famous is FMDB, it's in
Objective-C (obviously works well also in Swift), but if you prefer something completely in Swift, you can look at SwiftSQLite
Related
Here is my scenario, i am parsing via javascript a webpage and then post the result to an restApi to store the json in a db. The code works fine as long as all fields i defined in my script are send. Problem is over time they website might change names for fields and that would cause my code to crash.
Originally i used code like this
const mySchool = new mls.School();
mySchool.highSchoolDistrict = data["HIGH SCHOOL DISTRICT"].trim();
mySchool.elementary = data.ELEMENTARY.trim();
mySchool.elementaryOther = data["ELEMENTARY OTHER"].trim();
mySchool.middleJrHigh = data["MIDDLE/JR HIGH"].trim();
mySchool.middleJrHighOther = data["MIDDLE/JR HIGH OTHER"].trim();
mySchool.highSchool = data["HIGH SCHOOL"].trim();
mySchool.highSchoolOther = data["HIGH SCHOOL OTHER"].trim();
newListing.school = mySchool;
but when the element does not exist it complains about that it can not use trim of undefined. So to fix this i came up with this
if (data["PATIO/PORCH"]) {
newExterior.patioPorch = data["PATIO/PORCH"].trim();
}
this works but i am wondering if there is a more global approach then to go and check each field if it is defined ?
You could leverage a sort of helper function to check first if the item is undefined, and if not, return a trim()-ed version of the string.
var data = Array();
data["HIGH SCHOOL DISTRICT"] = " 123 ";
function trimString(inputStr) {
return (inputStr != undefined && typeof inputStr == "string") ? inputStr.trim() : undefined;
}
console.log(trimString(data["HIGH SCHOOL DISTRICT"]));
console.log(trimString(data["ELEMENTARY OTHER"]));
I have a class Node extends V. I add instances to Node with some set of document type information provided. I want to query the OrientDB database and return some information from Node; to display this in a formatted way I want a list of all possible field names (in my application, there are currently 115 field names, only one of which is a property used as an index)
To do this in pyorient, the only solution I found so far is (client is the name of the database handle):
count = client.query("SELECT COUNT(*) FROM Node")[0].COUNT
node_records = client.query("SELECT FROM Node LIMIT {0}".format(count))
node_key_list = set([])
for node in node_records:
node_key_list |= node.oRecordData.keys()
I figured that much out pretty much through trial and error. It isn't very efficient or elegant. Surely there must be a way to have the database return a list of all possible fields for a class or any other document-type object. Is there a simple way to do this through either pyorient or the SQL commands?
I tried your case with this dataset:
And this is the structure of my class TestClass:
As you can see from my structure only name, surname and timeStamp have been created in schema-full mode, instead nameSchemaLess1 and nameSchemaLess1 have been inserted into the DB in schema-less mode.
After having done that, you could create a Javascript function in OrientDB Studio or Console (as explained here) and subsequently you can recall it from pyOrient by using a SQL command.
The following posted function retrieves all the fields names of the class TestClass without duplicates:
Javascript function:
var g = orient.getGraph();
var fieldsList = [];
var query = g.command("sql", "SELECT FROM TestClass");
for (var x = 0; x < query.length; x++){
var fields = query[x].getRecord().fieldNames();
for (var y = 0; y < fields.length; y++) {
if (fieldsList == false){
fieldsList.push(fields[y]);
} else {
var fieldFound = false;
for (var z = 0; z < fieldsList.length; z++){
if (fields[y] == fieldsList[z]){
fieldFound = true;
break;
}
}
if (fieldFound != true){
fieldsList.push(fields[y]);
}
}
}
}
return fieldsList;
pyOrient code:
import pyorient
db_name = 'TestDatabaseName'
print("Connecting to the server...")
client = pyorient.OrientDB("localhost", 2424)
session_id = client.connect("root", "root")
print("OK - sessionID: ", session_id, "\n")
if client.db_exists(db_name, pyorient.STORAGE_TYPE_PLOCAL):
client.db_open(db_name, "root", "root")
functionCall = client.command("SELECT myFunction() UNWIND myFunction")
for idx, val in enumerate(functionCall):
print("Field name: " + val.myFunction)
client.db_close()
Output:
Connecting to the server...
OK - sessionID: 54
Field name: name
Field name: surname
Field name: timeStamp
Field name: out_testClassEdge
Field name: nameSchemaLess1
Field name: in_testClassEdge
Field name: nameSchemaLess2
As you can see all of the fields names, both schema-full and schema-less, have been retrieved.
Hope it helps
Luca's answer worked. I modified it to fit my tastes/needs. Posting here to increase the amount of OrientDB documentation on Stack Exchange. I took Luca's answer and translated it to groovy. I also added a parameter to select the class to get fields for and removed the UNWIND in the results. Thank you to Luca for helping me learn.
Groovy code for function getFieldList with 1 parameter (class_name):
g = orient.getGraph()
fieldList = [] as Set
ret = g.command("sql", "SELECT FROM " + class_name)
for (record in ret) {
fieldList.addAll(record.getRecord().fieldNames())
}
return fieldList
For the pyorient part, removing the database connection it looks like this:
node_keys = {}
ret = client.command("SELECT getFieldList({0})".format("'Node'"))
node_keys = ret[0].oRecordData['getFieldList']
Special notice to the class name; in the string passed to client.command(), the parameter must be encased in quotes.
For an application I'm running a query on DocumentDb in .NET. For this used I wanted to use a parametrized query, like this:
var sqlString = "select p.Id, p.ActionType, p.Type, p.Region, a.TimeStamp, a.Action from History p join a in p.Actions where a.TimeStamp >= #StartTime and a.TimeStamp <= #EndTime and p.ClientId = #ClientId and p.ActionType = #ActionType";
if (actionType != "") { sqlString += actionTypeFilter; }
var queryObject = new SqlQuerySpec
{
QueryText = sqlString,
Parameters = new SqlParameterCollection()
{
new SqlParameter("#StartTime", startDate),
new SqlParameter("#EndTime", endDate),
new SqlParameter("#ClientId", clientId.ToString()),
new SqlParameter("#ActionType", actionType)
},
};
var dataListing = _documentDbClient.CreateDocumentQuery<PnrTransaction>(UriToPnrHistories, queryObject, new FeedOptions() { MaxItemCount = 1 });
When I execute this, I'm getting en empty dataset. But when I use the same query, and build it using classic string replace it works just fine.
Can anyone tell me what I'm doing wrong in my parametrized query?
If the code above is the running code, you still add the actiontypeFilter on the parameterized SQL string. Try to remove the if statement on line 2. Seems to me that may be your problem.
It would help if you could post a sample document from the server.
I usually see this syntax:
SqlParameterCollection parameters = new SqlParameterCollection();
parameters.Add(...);
parameters.Add(...);
Try that and see if you get different results. It might be that the list you use to initialize it in your answer needs to be typed differently to work.
is there a way to deserialize strings to objects in actionscript:
i.e.
var str:String = "{ id: 1, value: ['a', 500] }";
should be made into an appropriate actionscript object.
this is not json, since the keys are not wrapped in quotes.
Ok, for that type of data pattern, there's not a nice way that I know of to do this. going off the assumption you can't affect the data to make it more JSON-like ... here's off the top of my head what I would conceptually try:
var str:String = "{ id:1, value:['a', 500] }";
// strip off the { and } characters since we've nothing nice to do that for us...
var mynewString:String = str.slice(1, str.length - 1);
var stringItems:Array = mynewString.split(",");
var obj:Object = new Object();
for (var i in stringItems)
{
var objProps:Array = stringItems[i].split(":");
// kill off the quotes here
obj[props[0]] = objProps[1].slice(1, objProps[1].length - 1);
if ( obj[props[0]].indexOf('[') == 0 ) {
// remove [ and ] if there
var maybeStrArray:String = obj[props[0]].slice(1, str.length - 1);
// right now assume we're an array based on our inbound data
var strArr:Array = maybeStrArray.split(",");
obj[props[0]] = strArr;
}
}
Something like that or similar to it anyway. Yes, it's crude, and absolutely it could be fashioned in a way that is more flexible (such as move the string to array convert to its own function so I could use it elsewhere). It's just the first thing that conceptually came to mind as an answer.
Try that, tweak around with it and see if it helps.
You can use as3corelib library for JSON deserialization. It's really not worth spending your time on writing own implementation (except you wish so).
Given a collection of items { url: 'http://blah' }. How can I tell if a record exists where the url is "http://stackoverflow.com"?
P.s. I am communicating with the c# driver
For any of the previous suggestions to be efficient you should be sure that there is an index on the url element. Otherwise a full collection scan will be required.
If you only expect the answer to be 0 or 1, count is probably the most efficient approach. If you think the count will be very large and all you really care about is whether there is one or more, FindOne is the most efficient approach.
It probably doesn't matter that FindOne returns the whole document unless the document is actually rather large. In that case you could tell the server to only return one field (the _id seems the most likely candidate):
var query = Query.EQ("url", "http://stackoverflow.com");
var fields = Fields.Include("_id");
var res = collection.Find(query).SetFields(fields).SetLimit(1).FirstOrDefault();
if (res == null) {
// no match found
}
you simply need check count of items returned by the query:
int count = collection.FindAs<Item>(Query.EQ("url", "http://stackoverflow.com")).Count();
if(count > 0)
{
//do some stuff
}
IMongoQuery query = Query.EQ("url", "http://stackoverflow.com");
var res = collection.FindOne(query);
if(res == null)//don't exist
{
}
Existence of Key in MongoDB can check by using Exists and second parameter as true or false
var filter = builder.Exists("style", false);
var RetrievedData = collection.Find(filter).ToList()
Refference Link