evaluate template question

[[email protected]]

I am trying to use evaluate_template to represent the name of
the field in a table during a typical data entry

i know the following codes not running, can someone suggest
an equivalent to what i am trying to do,

the actual table has 50 field, depending on what data being submitted,
typcally only few fields per record get filled...
so i evaluate datax and datay

such variable will represnet my field name/

i like to automatically on the fly post data to corresponding field.

i hope i am explaining myself well

dim datax as c
dim datay as c

datax = "name_field"
datay = "city"

DIM tbl AS P
tbl=TABLE.OPEN("test_data.dbf",FILE_RW_SHARED)
tbl.ENTER_BEGIN()

tbl.evaluate_template(datax) = "walmart"
tbl.evaluate_template(datay) = "chicago"
tbl.enter_end(.t.)
tbl.close()

[Tim Kiebert]

Re: evaluate template question

Ken,

Checkout the help on the difference between eval() and evaluate_template(). (If you havn't already.)

Eval() returns a value after evaluating the expression where as Evaluate_template() executes a command that is represented within/by the expression.

According to the help on table functions you can use tbl.eval() but not tbl.evaluate_template().

"All very interesting but how then do I do what I want?", I can hear you saying.

I can't test at the moment but I think this correct.

 dim datax as c
 dim datay as c
 
 datax = "name_field"
 datay = "city"
 
 DIM tbl AS P
 tbl=TABLE.OPEN("test_data.dbf",FILE_RW_SHARED)
 tbl.ENTER_BEGIN()
 
evaluate_template("tbl." +datax+ " = 'walmart'"
evaluate_template("tbl." +datay+ " = 'chicago'"

tbl.enter_end(.t.)
 tbl.close()

The result of

evaluate_template("tbl." +datax+ " = 'walmart'"

is

tbl.name_field = "walmart"

which then gets executed.

[Tim Kiebert]

Re: evaluate template question

If you just wanted to extract the value from the table field you could use tbl.eval().

dim value as C
 dim datax as c
 dim datay as c
 
 datax = "name_field"
 datay = "city"
 
 DIM tbl AS P
 tbl=TABLE.OPEN("test_data.dbf",FILE_RW_SHARED)
 
value = tbl.eval(datax) 

tbl.close()

[Stan Mathews]

Re: evaluate template question

Ken,

Checkout the help on the difference between eval() and evaluate_template(). (If you havn't already.)

Eval() returns a value after evaluating the expression where as Evaluate_template() executes a command that is represented within/by the expression.

According to the help on table functions you can use tbl.eval() but not tbl.evaluate_template().

"All very interesting but how then do I do what I want?", I can hear you saying.

I can't test at the moment but I think this correct.

 dim datax as c
 dim datay as c
 
 datax = "name_field"
 datay = "city"
 
 DIM tbl AS P
 tbl=TABLE.OPEN("test_data.dbf",FILE_RW_SHARED)
 tbl.ENTER_BEGIN()
 
evaluate_template("tbl." +datax+ " = 'walmart'"
evaluate_template("tbl." +datay+ " = 'chicago'"

tbl.enter_end(.t.)
 tbl.close()

The result of

evaluate_template("tbl." +datax+ " = 'walmart'"

is

tbl.name_field = "walmart"

which then gets executed.

I think you're missing some closing parentheses.......

evaluate_template("tbl." +datax+ " = 'walmart'"[COLOR="Red"])[/COLOR]
evaluate_template("tbl." +datay+ " = 'chicago'"[COLOR="red"])[/COLOR]

If it was me, I'd blame it on my eyesight.

I don't think tbl.evaluate_template() would make sense. Tbl.eval() is just a shortcut (?), as in

tbl.eval("firstname+lastname")

instead of

tbl.firstname+tbl.lastname

which when you look at it is not really shorter.

[[email protected]]

Re: evaluate template question

I am not sure, will test it out, in the similar idea with sql statement:

is it possible to use eval or evaluate_template to change the field(that i wish to insert) of an sql table

dim connString as C

dim conn as ole::adodb.connection
connString = "DRIVER={MySQL ODBC 3.51 Driver};SERVER=localhost;DATABASE=logistic;UID=root;PWD=alpha5v7"
conn.open(connString)

dim yvr1 as c
dim yvr2 as c
dim yvr3 as c
dim dvr1 as c
dim dvr2 as c
dim dvr3 as c

yvr1 = "name" ' this i expect this field name to change depending of what data come in
yvr2 = "address" ' this one also changing
yvr3 = "city" ' this one also,

this sql table has 100 field(names), example, name, address, city, id, and more....

depending of what xml data coming in, i need to poulate to some of the fields on this big table with little data, quite empty look example above, the name,address & city required insert

while later on, it might be, something else like id, location,distance
all typical 3 fields at a time on my example, real life can be upto 20 plus fields
that is why the need to use variables just makes it easier/

dvr1 = remspecial(time())
dvr2 = "11111 west avenue"
dvr3 = "new york"

rs = conn.Execute("INSERT INTO customer (name, address, city) VALUES ('"+dvr1+"','"+dvr2+"','"+dvr3+"')")


where i can subsitute the rs statement:

rs = conn.Execute("INSERT INTO customer (variable?, variable?, variable?) VALUES ('"+dvr1+"','"+dvr2+"','"+dvr3+"')")

can i use eval ?

truly i am not familiar, just managed to get moving one step at a time/
i can do this well with alpha native table, but the need to go sql is mandatory

appriciate your assistances

ken tjia

[Tim Kiebert]

Re: evaluate template question

Stan,
Thanks for the correction. Thats what I get for sneaking of to have a read of the forum instead of working.;)

I think you're missing some closing parentheses.......
Yep, oops.
If it was me, I'd blame it on my eyesight.
Well if they were there and I didn't see them I could. However since they weren't there and I thought they were I'm not sure what to blame it on..... please be kind.


I don't think tbl.evaluate_template() would make sense.
Me either.
Tbl.eval() is just a shortcut (?), as in

tbl.eval("firstname+lastname")

instead of

tbl.firstname+tbl.lastname

which when you look at it is not really shorter.

Agreed as far as that example goes.
But in my second post above
value = tbl.eval(a_variable)
would allow you to dynamically change the field name referenced in the table pointer. Such as preceed that code with a dialog that asks "Get value for what field" and present the user with a list of fields with the choice going into a_variable.

[Tim Kiebert]

Re: evaluate template question

I am not sure, will test it out, in the similar idea with sql statement:

is it possible to use eval or evaluate_template to change the field(that i wish to insert) of an sql table

dim connString as C

dim conn as ole::adodb.connection
connString = "DRIVER={MySQL ODBC 3.51 Driver};SERVER=localhost;DATABASE=logistic;UID=root;PWD=alpha5v7"
conn.open(connString)

dim yvr1 as c
dim yvr2 as c
dim yvr3 as c
dim dvr1 as c
dim dvr2 as c
dim dvr3 as c

yvr1 = "name" ' this i expect this field name to change depending of what data come in
yvr2 = "address" ' this one also changing
yvr3 = "city" ' this one also,

this sql table has 100 field(names), example, name, address, city, id, and more....

depending of what xml data coming in, i need to poulate to some of the fields on this big table with little data, quite empty look example above, the name,address & city required insert

while later on, it might be, something else like id, location,distance
all typical 3 fields at a time on my example, real life can be upto 20 plus fields
that is why the need to use variables just makes it easier/

dvr1 = remspecial(time())
dvr2 = "11111 west avenue"
dvr3 = "new york"

rs = conn.Execute("INSERT INTO customer (name, address, city) VALUES ('"+dvr1+"','"+dvr2+"','"+dvr3+"')")


where i can subsitute the rs statement:

rs = conn.Execute("INSERT INTO customer (variable?, variable?, variable?) VALUES ('"+dvr1+"','"+dvr2+"','"+dvr3+"')")

can i use eval ?

truly i am not familiar, just managed to get moving one step at a time/
i can do this well with alpha native table, but the need to go sql is mandatory

appriciate your assistances

ken tjia

Since I have already embarrassed myself once in this thread I might as well try again. I have nil to very little experience building sql statements but it seems that you just need to construct a string that goes into the rs = conn.Execute() function. And I would say you are over half way there.

I would suggest

 rs = conn.Execute("INSERT INTO customer (" +yvr1+ "," +yvr2+ "," +yvr3+") VALUES ('"+dvr1+"','"+dvr2+"','"+dvr3+"')")

I tried this in the interactive window and seems to reflect what you need

yvr1 = "name" ' this i expect this field name to change depending of what data come in
yvr2 = "address" ' this one also changing
yvr3 = "city" ' this one also,

dvr1 = remspecial(time())
dvr2 = "11111 west avenue"
dvr3 = "new york"


sql_string = "INSERT INTO customer (" +yvr1+ ", " +yvr2+ ", " +yvr3+") VALUES ('"+dvr1+"','"+dvr2+"','"+dvr3+"')"

?sql_string
= "INSERT INTO customer (name, address, city) VALUES ('175341','11111 west avenue','new york')"

As you can see the data/values that is being passed in to the sql statement is enclosed in single quotes. Am not sure if that is ok. If not then you may need escaped double quotes

sql_string = "INSERT INTO customer (" +yvr1+ ", " +yvr2+ ", " +yvr3+") VALUES (\""+dvr1+"\",\""+dvr2+"\",\""+dvr3+"\")"
?sql_string
= INSERT INTO customer (name, address, city) VALUES ("175341","11111 west avenue","new york")

I think you could then follow that with

rs = conn.Execute(sql_string)

Caution:I don't know if 'sql_string' is or isn't a reserved sql word/command.

Stan: With all those quotes, escapes, and parentheses I hope you are proof reading this for me. ;)