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select multiple in admin

edited August 2013 in Apps

What would be a good way to use select multiple input fields on the admin side? Currently, I have something like this for a "plain old" select:

<select name="type">
    <option value="Type1"{% if type == 'Type1' %} selected{% end %}>Type1</option>
    <option value="Type2"{% if type == 'Type2' %} selected{% end %}>Type2</option>
    <option value="Type3"{% if type == 'Type3' %} selected{% end %}>Type3</option>

If I stored the choices in a comma or pipe delimited field, could I parse it in a template? I guess what I'm asking is what php the templates can use. Could I check to see if $type was in the array of types they had previously chosen?


  • Here's an example of a dynamically populated select box:

    Let me know if that answers your question.

  • edited August 2013

    I'm not sure if it addresses select multiple type inputs, where they can hold ctrl or cmd to select, say, Type1 and Type3. Then $type will be something like "Type1,Type3" and the edit page will need to preselect Type1 and Type3.

  • Ah I think I understand. Here's a modification of my previous gist for multi-select fields:

    I also wrapped it in an Elefant form so you could see the submitted values. Let me know if that works for you!

  • Thank you! I'll try it.

  • Do you have a recommendation for storing the array in the database? In the past I've used MySQL set and/or enum fields, but I get the sense those aren't quite kosher and I'm using sqlite for this site.

    I want urls like /app/foo to find all records that have foo among their types, etc.

    I could implode the array and do LIKE searches, but that seems inefficient.

    I could set up a bitwise function, but that code might get hard to read and maintain.

    I could use a join table, but I'm not quite sure how to integrate joins into elefant's database model.

    Does this give you enough information to answer the question?

  • Googled around a bit and found another option: one boolean column for each type in the database table.

  • Bitwise is generally a good option if you have a finite number of types. You can setup a few simple methods for each type check, then it keeps things fairly clean:

    Otherwise a join may be better for managing many-to-many type relationships. Here's an example of setting up a many-many join on two models in Elefant:

    Hope that helps!

  • It helps a ton. As always, thank you!

  • What do you make of the arguments against bitwise in some of the answers to this question?

  • I'd say that's a bit of an exaggerated example. Here's a much simpler SQL example based on Unix permissions (read/write/execute):

    -- create the table and index
    create table bitwise (
      name char(32) not null,
      val tinyint not null
    create index bitwise_val on bitwise (val);
    -- insert each possible value for r+w+e (
    insert into bitwise values ('none',      0);
    insert into bitwise values ('r',         1);
    insert into bitwise values ('w',         2);
    insert into bitwise values ('r + w',     3);
    insert into bitwise values ('e',         4);
    insert into bitwise values ('r + e',     5);
    insert into bitwise values ('w + e',     6);
    insert into bitwise values ('r + w + e', 7);
    -- fetch all rows that have no permissions
    select * from bitwise where val = 0;
    -- fetch all rows that are readable
    select * from bitwise where val & 1;
    -- fetch all rows that are writeable
    select * from bitwise where val & 2;
    -- fetch all rows that are executable
    select * from bitwise where val & 4;
    -- fetch all rows that are readable and writeable
    select * from bitwise where val & 1 and val & 2;
    drop table bitwise;

    And the argument that a DBA is going to be forced to understand and manipulate the schema with zero documentation is easily solved by documenting the schema. That's just responsible development IMO :)

    In MySQL you could use something more readable like an enum column, but that's a MySQL-specific column type.

  • What you say makes a lot of sense.

  • Getting back to this...

    I have a join table with a many-many relationship like you outlined above. I want to let the user add and delete relationships. Are there elefant methods for that or should I write SQL queries? I can elaborate on what I'm trying to do if that would be helpful.

  • Elefant's Model currently only offers convenience methods for fetching relationships, not for inserts or updates. I usually just write a custom method on my model that does whatever insert logic I need, usually via DB::execute().

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