I tried using this .get method and it doesn't work. Any idea why? This is from the docs:
Zoo.get('DFW')
Zoo.get('Metro', 'DFW')
I assume that the Zoo model has a name column that has a name like "DFW" (David foster wallace?).
It doesn't work though when I try this syntax is terminal. All the get method seems to accept is a primary key.
Related
I have the following code:
mytable.to_sql(name='mytable', con=engine, index=True, if_exists='replace')
But it keeps throwing the following error:
'(1170, "BLOB/TEXT column 'index' used in key specification without a key length")'[SQL: CREATE INDEX ix_mytable_index ON mytable (index)]
I think I understand why the error happens but in the context for the code above I don't know how to specify the length. I can't change the underlying database since this code was handed down to me.
I am trying to create mysql table using groovy domain class. I have one master table and other table with has reference to field in the master table.
Let me explain more clearly. I have a master table
QualificationMaster
`````````````````
QualificaitonID
QualificationName
QualificaitonDuration
UserQualificationMap
```````````````````
Username
Email
QualificationID (this field refers to QualificationID in QualificationMaster)
Please help me in getting this done by using groovy domain class with sample snippet...I searched a lot but I find it so confusing..please help me as i am very new to groovy and helps me a lot. I am using GGTS IDE for this.
Check this out:
class QualificationMaster{
String QualificationName
Integer QualificaitonDuration
}
class UserQualificationMap{
String Username
String Email
QualificationMaster Qualification
}
You do not have to use QualificationMaster.QualificaitonID as primary key for QualificationMaster. QualificationMaster.id is created by default for each domain class (you can check it in your db).
Therefore you can make a reference to QualificationMaster from UserQualificationMap. It will be mapped as QualificationMaster's primary key in UserQualificationMap table.
Moreover try to use shorter and lowercased names for properties in your domain classes. For example change QualificationMaster.QualificationName to QualificationMaster.name and QualificationMaster.QualificaitonDuration to QualificationMaster.duration.
I'm new to Perl and DBIx::Class.
This is how I get my meaning_ids from the table translation where language = 5:
my $translations = $schema -> resultset('Translation')->search({ language => '5'});
After it I'm trying to push my data from the database into my array data:
while ( my $translation =$translations->next ) {
push #{ $data }, {
meaning_id => $translation-> meaning
};
}
$self->body(encode_json $data );
If I do it like this, I get the following error:
encountered object
'TranslationDB::Schema::Result::Language=HASH(0x9707158)', but neither
allow_blessed , convert_blessed nor allow_tags settings are enabled
(or TO_JSON/FREEZE method missing)
But if I do it like that:
while ( my $translation =$translations->next ) {
push #{ $data }, {
meaning_id => 0+ $translation-> meaning
};
}
$self->body(encode_json $data );
I don't get the error anymore, but the meaning is not the number out of the database. It's way too big (something like 17789000, but only numbers till 7000 are valid).
Is there an easy way to tell Perl that meaning_id is an INT and not a string?
It's a bit hard without knowing your schema classes, but #choroba is right. The error message says $translation->meaning is an instance of TranslationDB::Schema::Result::Language. That's explained in DBIx::Class::Manual::ResultClass on CPAN.
I believe there is a relationship to a table called meaning, and when you call $translation->meaning what you get is a new result class. Instead you need to call $translation->meaning_id. Actually that would only happen in a join, but your code doesn't look like it does that.
It seems $translation->meaning returns an object. Using 0+ just returns its address (that's why the numbers are so high).
It looks like there's a relationship between your translation and meaning tables. Probably, the translation table contains a foreign key to the meaning table. If you look in the Result class for your translation class then you will see that relationship defined - it will be called "meaning".
As you have that relationship, then DBIC has added a meaning method to your class which retrieves the meaning object that is associated with your translation.
But it appears that the foreign key column in your translation table is also called "meaning", so you expect calling the "meaning" method gives you the value of the foreign key rather than the associated object. Unfortunately it doesn't work like that. The relationship method overrides the column method.
This is a result of bad naming practices. I recommend that you call the primary key for every table id and the foreign key that links to another table <table_name>_id - so the column in your translation table would be called meaning_id. That way you can distinguish between the value of the key ($translation->meaning_id) and the associated meaning object ($translation->meaning).
A work-around you can use if you can't rename columns, is to use the get_column method - $translation->get_column('meaning').
I have two tables which are Many-To-One mapped. However, it is important to maintain the order of the second table, so when I use automapping, Fluent automapper creates a bag. I changed this to force a list by using this command:
.Override(Of ingredients)(Function(map) map.HasMany(Function(x) x.PolygonData).AsList())
(VB.NET syntax)
So I say "AsList" and instead of using a bag, the mapping xml which gets generated contains a list now. Fine so far. However,
the statement generated cannot be handled by MySQL. I use MySQL55Dialect to create the statements and I use exactly that version. But it creates the following create:
create table `ingredients` (
Id INTEGER NOT NULL AUTO_INCREMENT,
Name FLOAT,
Amout FLOAT,
Soup_id INTEGER,
Index INTEGER,
primary key (Id)
)
It crashes because of the line "Index INTEGER," but I don't know what to do here. Any ideas?
Thanks!!
Best,
Chris
I would suspect that Index could be a keyword for MySQL. To avoid such conflict, we can define different Index column name (sorry for C# notation)
HasMany(x => x.PolygonData)
.AsList(idx => idx.Column("indexColumnName").Type<int>())
I am working to use django's ContentType framework to create some generic relations for a my models; after looking at how the django developers do it at django.contrib.comments.models I thought I would imitate their approach/conventions:
from django.contrib.comments.models, line 21):
content_type = models.ForeignKey(ContentType,
verbose_name='content type',
related_name="content_type_set_for_%(class)s")
object_pk = models.TextField('object ID')
content_object = generic.GenericForeignKey(ct_field="content_type", fk_field="object_pk")
That's taken from their source and, of course, their source works for me (I have comments with object_pk's stored just fine (integers, actually); however, I get an error during syncdb on table creation that ends:
_mysql_exceptions.OperationalError: (1170, "BLOB/TEXT column 'object_pk' used in key specification without a key length")
Any ideas why they can do it and I can't ?
After looking around, I noticed that the docs actually state:
Give your model a field that can store a primary-key value from the models you'll be relating to. (For most models, this means an IntegerField or PositiveIntegerField.)
This field must be of the same type as the primary key of the models that will be involved in the generic relation. For example, if you use IntegerField, you won't be able to form a generic relation with a model that uses a CharField as a primary key.
But why can they do it and not me ?!
Thanks.
PS: I even tried creating an AbstractBaseModel with these three fields, making it abstract=True and using that (in case that had something to do with it) ... same error.
After I typed out that really long question I looked at the mysql and realized that the error was stemming from:
class Meta:
unique_together = (("content_type", "object_pk"),)
Apparently, I can't have it both ways. Which leaves me torn. I'll have to open a new question about whether it is better to leave my object_pk options open (suppose I use a textfield as a primary key?) or better to enforce the unique_togetherness...