Django CharField vs TextField

Question

What is the difference between CharField   and TextField   in Django   The documentation says that CharField   should be used for smaller strings and TextField   should be used for larger strings   Okay  but where is the line drawn between  small  and  large    What s going on under the hood here that makes this the case

User · Answer

In some cases it is tied to how the field is used. In some DB engines the field differences determine how (and if) you search for text in the field. CharFields are typically used for things that are searchable, like if you want to search for "one" in the string "one plus two". Since the strings are shorter they are less time consuming for the engine to search through. TextFields are typically not meant to be searched through (like maybe the body of a blog) but are meant to hold large chunks of text. Now most of this depends on the DB Engine and like in Postgres it does not matter.

Even if it does not matter, if you use ModelForms you get a different type of editing field in the form. The ModelForm will generate an HTML form the size of one line of text for a CharField and multiline for a TextField.

User · Answer

It s a difference between RDBMS s varchar  or similar      those are usually specified with a maximum length  and might be more efficient in terms of performance or storage     and text  or similar  types     those are usually limited only by hardcoded implementation limits  not a DB schema    PostgreSQL 9  specifically  states that  There is no performance difference among these three types   but AFAIK there are some differences in e g  MySQL  so this is something to keep in mind   A good rule of thumb is that you use CharField when you need to limit the maximum length  TextField otherwise   This is not really Django-specific  also

User · Answer

For eg    2 fields are added in a model like below   description   models TextField blank True  null True  title   models CharField max length 64  blank True  null True   Below are the mysql queries executed when migrations are applied   for TextField description  the field is defined as a longtext ALTER TABLE  sometable sometable  ADD COLUMN  description  longtext NULL   The maximum length of TextField of MySQL is 4GB according to string-type-overview   for CharField title  the max length required  is defined as varchar 64  ALTER TABLE  sometable sometable  ADD COLUMN  title  varchar 64  NULL  ALTER TABLE  sometable sometable  ALTER COLUMN  title  DROP DEFAULT

User · Answer

CharField has max length of 255 characters while TextField can hold more than 255 characters  Use TextField when you have a large string as input  It is good to know that when the max length parameter is passed into a TextField it passes the length validation to the TextArea widget

User · Answer

I had an strange problem and understood an unpleasant strange difference  when I get an URL from user as an CharField and then and use it in html a tag by href  it adds that url to my url and that s not what I want  But when I do it by Textfield it passes just the URL that user entered  look at these  my website address  http   myweb com  CharField entery  http   some-address com  when clicking on it  http   myweb comhttp   some-address com  TextField entery  http   some-address com  when clicking on it  http   some-address com  I must mention that the URL is saved exactly the same in DB by two ways but I don t know why result is different when clicking on them

[sql] Django CharField vs TextField

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